N = 9430). All 79 primary schools in Bergen participated in the study. Both teacher (8809 complete cases) and parent (6253 complete cases) report were used in the analyses. ADHD and ODD scores were estimated using the Swanson Noland and Pelham rating scale version IV (SNAP-IV), and peer problems and prosocial behavior were assessed using the Strengths and Difficulties Questionnaire (SDQ). We replicated the relationship between peer problems and prosocial behavior found previously in typically developing children. Our results showed that the relationship between peer problems and prosocial behavior became weaker as the ODD symptoms increased in number and severity. For ADHD this effect was only found in the teacher report of the children. A sex effect for ODD symptoms was found only using the parent report: boys with ODD symptoms showed less prosocial behavior than girls with similar levels of ODD symptoms. Since this effect was not found using the teacher data, it may imply a situational effect (school/home) for girls with high levels of ODD. The moderator effect of ODD/ADHD was comparable for boys and girls. Our findings suggest that even if children with ADHD/ODD symptoms have the opportunity to practice their social skills in peer relationships, this is not necessarily accompanied by an increase in prosocial behavior.Oppositional defiant disorder (ODD) and attention-deficit/hyperactivity disorder (ADHD) are characterized by symptoms that hinder successful positive interaction with peers. The main goal of this study was to examine if the presence of symptoms of ODD and ADHD affects the relationship between positive social behavior and peer status found in 7–9-year-old children who show symptoms typical of ADHD and/or ODD. Furthermore, the possible interaction with sex was investigated. We used data collected in the first wave of The Bergen Child Study of mental health (BCS), a prospective longitudinal total population study of children's developmental and mental health. The target population consisted of children in the second to the fourth, in all public, private, and special schools in Bergen, Norway, in the fall of 2002 ( Oppositional defiant disorder (ODD) and attention-deficit/hyperactivity disorder (ADHD) are characterized by symptoms that, by their very nature, are likely to hinder successful positive interaction with peers (see ). While Unsurprisingly, difficulties with interacting positively and constructively with peers are frequently reported in children with ODD and/or ADHD –17. Chil These findings suggest that children with ODD and/or ADHD may be at a serious disadvantage with regard to their social development. Research has shown that positive social skills such as friendly and cooperative behavior, and prosocial behaviors such as giving emotional support, showing empathy and sharing, allow children to succeed on social tasks and are associated with peer popularity; children who demonstrate poor social skills, disruptive, physically aggressive, and antisocial behavior, however, have been shown to be at risk of experiencing peer rejection –24. FurtHowever, it is not yet clear how peer relationships and social behavior are associated in children with ODD and/or ADHD. While well-liked typically developing children combine high levels of positive social behaviors with low levels of negative social behaviors, children with ADHD may, for example, show high levels of both positive and negative social behavior. Research suggests that children with ADHD are not unwilling to or at a loss how to behave in a prosocial manner. Blachman and Hinshaw , for exatype of negative social behavior shown by children with ADHD [ According to the DSM-IV-TR, ODD is more prevalent in boys than girls before puberty . ADHD isith ADHD . More spith ADHD . While tith ADHD . Girls with ADHD –33. ThisWe expect to replicate the relationship between peer relations and prosocial behavior in typically developing children, in a population based study. The more ODD/ADHD symptoms a child displays, the weaker the relationship between peer problems and prosocial behavior (moderator effect of ODD/ADHD). We expect that the moderating effect of ODD/ADHD symptoms is larger for girls than for boys.The purpose of this study was to determine whether the relationship between peer problems and prosocial behavior found in children who show symptoms typical of ODD and/or ADHD is similar to the one found in typically developing children. We will test three hypotheses.The current study uses data collected in the first wave of The Bergen Child Study of mental health (BCS), an ongoing prospective longitudinal total population study of children's developmental and mental health. The main aim of the BCS is to establish reliable prevalence data for mental health problems in children in a total population. For more information about the BCS we refer to Heiervang et al. . The stuN = 9430). Bergen is the second largest city of Norway, with a total population of around 235,000. All 79 primary schools in Bergen participated in the study. In the first stage of the BCS, a four-page screening instrument was completed by both teachers and parents. The screening instrument was sent to the teachers, together with a letter explaining the purpose of the study and an informed consent form. The teachers were asked to pass on an extra copy to all the parents of children in their class; the parents of 7007 children agreed to participate and returned a signed informed consent form. As a special feature of the study, teachers returned completed questionnaires even when the informed consent form was not returned by the parents, but without any personal identification, to ensure that these questionnaires could not be traced to individual children [The target population consisted of children in the second to the fourth grade in all public, private, and special schools in Bergen, Norway, in the fall of 2002  items, or Strengths and Difficulties Questionnaire (SDQ) items was implemented in each separate file. The parent file contained 6253 complete cases  and the teacher file contained 8809 complete cases . The four-paged screening instrument included the Strengths and Difficulties Questionnaire (SDQ), a brief multidimensional measure of psychological adjustment of children aged 3 to 16 years , 38, andThe SDQ consists of 25 items that are scored on a 3-point scale . The 25 items are meant to cover five dimensions, each consisting of five items, generating scores for the following: hyperactivity, emotional symptoms, conduct problems, peer problems, and prosocial behavior. In our study, we used the latter two. The questionnaire can be completed by the parents and/or teachers of 4- to 16-year-olds. The SDQ is available in over 40 languages . A recenall ADHD items as an indicator for ADHD in this study. IRT is becoming increasingly popular in psychiatric research, both for analyzing the dimensional structure of questionnaires [The SNAP-IV comprises 26 items divided over three subscales: Inattentiveness (nine items), Hyperactivity/Impulsivity (nine items), and Oppositional behavior (eight items). On the original form, the items are scored on a 4-point scale  . In the onnaires –50, as wonnaires , 52). A onnaires .P value of the previously entered variables, as well as multicollinearity diagnostics. We started with the control variables sex and grade, and continued by adding peer problems, ADHD, ODD, and the moderator effects (peer problems × ADHD/ODD). All regression analyses were performed in SPSS 16 [Separate regression analyses for parents and teachers were used to determine whether peer problems predicted  prosocial behavior. We standardized all variables prior to the regression analyses. This allowed us to determine whether the linear regression models based on parent and teacher data, respectively, were similar. Prosocial behavior served as a dependent variable, and ADHD, ODD, sex , and grade  served as independent variables. To test whether a high number of ADHD/ODD symptoms moderated the effect between peer problems and prosocial behavior, we included interaction effects in our models. We also tested whether there was a significant interaction between sex and ADHD/ODD. The models were built using a forward procedure, adding one variable at a time and checking whether it was significant; but also monitoring its potential impact on the size and  SPSS 16 .P < 0.001. two final models were estimated . Children in second grade showed somewhat less prosocial behavior than children in fourth grade, this effect was significant . The difference between third and fourth graders was not significant . Although the effect of peer problems was significant for both data-sets (P < 0.001 for both parent and teacher report), it was about twice as large when based on the teacher data. The same applies to the effect of ADHD-score (P < 0.001 for both parent and teacher report). The effect of ODD was also significant, and larger than the effect of ADHD . Thus, an increase in ADHD or ODD symptoms was accompanied by a decrease in prosocial behavior. The moderator effect of ADHD was only significant for the teacher data; children with higher levels of ADHD showed a weaker relationship between peer problems and prosocial behavior (P < 0.001). The moderator effect of ODD was significant in both data-sets (P < 0.001 for both parent and teacher report). In the parent data-set, an interaction was found between sex and ODD; a stronger relationship between prosocial behavior and ODD symptoms was found for boys compared to girls (P = 0.003).The effect of sex and grade was similar in size for the parent and teacher data-sets. Boys displayed significantly less prosocial behavior than girls  population-based study, we feel confident about the generalizability of these findings. As noted by Veenstra et al. [ Previous studies have shown a relationship between peer status and prosocial behavior in various age-groups and countries. Our findings provide further support for this relationship in 7–9-year-old children. Importantly, we found a relationship between peer problems and prosocial behavior, even when other variables were taken into account (such as sex and ADHD/ODD). Since we used a very large  these children tend to overestimate their own social competence more than typically developing children do [ Collectively, our findings suggest that symptoms that are associated with attention-deficit and disruptive behavior disorders moderate the relationship between peer problems and prosocial behavior. More specifically, children reported to display clinical levels (>95th percentile) of ADHD/ODD show very little prosocial behavior, regardless of whether or not they are reported to have problems with peers. As mentioned before, the relationship between peer status and prosocial behavior is thought to be reciprocal; however, our findings may imply that this is not necessarily true for children with high levels of ADHD/ODD symptoms. Even those children with a high level of reported ADHD/ODD symptoms that have ldren do . Indeed,ldren do . Linnea ldren do  did not Although not the main focus of our study, the finding that girls had a higher prosocial score than boys warrants some discussion. This finding in favor of girls is quite consistent in the literature , 58–61. In this study, we used both parent and teacher ratings. It is important to note that informants tend to differ in their perceptions of and interactions with children, and that these take place in different situations which may provoke different types of behavior in children. As noted by Veenstra et al. , a highlThe most important differences between teacher and parent report were as follows: the weaker overall relationship between prosocial behavior and peer problems, the absence of the moderating effect of ADHD in the parent data, and the presence of an interaction of ODD symptoms and sex in the parent data. Currently, we can only speculate about possible explanations. We expect that teachers have ample opportunity to observe a relationship between the child's conduct  and peer status. However, if children do not have a lot of friends (possibly due to conduct problems), parents may not be in the position to judge the relationship between peer problems and prosocial behavior very well. Not only would there be little opportunity to observe social interactions, but the diversity of these behaviors may also be limited if the child only has one or two friends. This may explain the weaker relationship between peer status and prosocial behavior reported by parents. On the other hand, parents have the opportunity to observe their child's behavior outside of the class-room setting. Maybe girls with high levels of ODD symptoms act out more at school when interacting with a peer-group that may be partly hostile towards them, but show more prosocial behavior at home when interacting with their friend(s) or siblings. In a recent study, Mikami and Lorenzi  found th Even though the screening measure we used to measure ADHD and ODD directly reflected the symptoms for ADHD and ODD as they are listed in the DSM-IV, we cannot rule out that some of the ODD/ADHD symptoms were actually caused by other disorders. For example, several symptoms of increased arousal in PTSD show an overlap with ADHD (and ODD) symptoms, such as sleeplessness, irritability, or anger, difficulty concentrating, hypervigilance, and exaggerated startle response . We concIn summary, we replicated earlier findings that girls show more prosocial behavior than boys, and that peer relations and prosocial behavior are correlated. Moreover, we found support for our hypothesis that symptoms indicative of ADHD (teacher report only) and ODD moderate (weaken) the relationship between peer relations and prosocial behavior. Since prosocial behavior has been found to be a key predictor for future social adjustment , it is


The present study aimed to measure the prevalence of adult attention deficit hyperactivity disorder (ADHD) in a large, representative sample of young Swiss men and to assess factors associated with this disorder.Our sample consisted of 5656 Swiss men (mean age 20 years) who participated in the Cohort Study on Substance Use Risk Factors (C-SURF). ADHD was assessed with the World Health Organization (WHO) adult ADHD Self Report Screener (ASRS). Logistic regression analyses were conducted to assess the association between ADHD and several socio-demographic, clinical and familial factors.The prevalence of ADHD was 4.0%, being higher in older and French-speaking conscripts. A higher prevalence also was identified among men whose mothers had completed primary or high school/university and those with a family history of alcohol or psychiatric problems. Additionally, adults with ADHD demonstrated impairment in their professional life, as well as considerable mental health impairment.Our results demonstrate that ADHD is common among young Swiss men. The impairments in function and mental health we observed highlight the need for further support and interventions to reduce burden in affected individuals. Interventions that incorporate the whole family also seem crucial. According to the DSM-IV-TR The functional impairment and poor mental health that many experience can have a cumulative effect over the course of one’s life To date, the prevalence of ADHD has mainly been investigated in children and adolescents. In the limited number of studies that have focused on adults, prevalence estimates for ADHD have varied considerably, ranging from 1.0 to 7.5% , meaning that it is one of the most common psychiatric disorders observed in this age group The aims of the present study were (1) to measure the prevalence of adult ADHD within a large, representative sample of young Swiss men; and (2) to identify factors associated with this disorder in this age-group. To our knowledge, this is the largest sample of young men used in a population-based study in Europe to estimate the prevalence of adult ADHD.‘Cohort Study on Substance Use Risk Factors’ (C-SURF), a longitudinal study designed to assess substance use patterns within a cohort of young Swiss men. The study was approved by the Ethics Committee for Clinical Research at Lausanne University Medical School (protocol number 15/07) and informed written consent was obtained from the participants.The present study used data drawn from the The sample was recruited between August 2010 and November 2011 at three of a total of six centres that recruit men for military service, covering 21 of 26 Swiss cantons . Switzerland has a mandatory army recruitment process, such that all Swiss men must submit to a formal evaluation to determine their eligibility for military service, civil service, or no service at approximately age 19. Both those who were deemed eligible to serve in the army and those deemed ineligible for military service were eligible for enrolment in our study. As there is no pre-selection to army conscription, a representative sample of young Swiss men was thereby provided for the study. It is important to note that the army centres were used only to enrol participants into the study. Both the study itself and the men’s decision to participate were entirely independent of the army. The present study used data collected during the baseline assessment only.A total of 7,563 conscripts gave informed consent to participate in the study. Among them, 5,990 (79.2%) completed the baseline questionnaire. A further 334 conscripts were excluded from the analysis due to missing data, so that the final sample consisted of 5,656 (74.8%) subjects.Adult ADHD was assessed using the Adult ADHD Self-Report Scale Screener (ASRS-v1.1), developed by the World Health Organization (WHO) Participants who failed to answer at least three questions from the ASRS Screener were excluded . In contrast, when participants failed to answer only one or two questions, these missing responses were replaced by means of nearest-neighbour hot-deck imputation, using a random recursive partitioning (RRP) dissimilarity matrix. This method was implemented within the RRP package Socio-demographic variables included age (‘younger than 20 years’ vs. ‘20 years or older’), linguistic region (‘German-’ vs. ‘French-speaking’), residence , marital status (‘in relationship’ vs. ‘single’), highest achieved education , and degree of financial autonomy . Additionally, several socio-demographic variables related to the subject’s childhood were assessed, including maternal education , family affluence (‘above average’ vs. ‘average’ vs. ‘below average’), living arrangement before the age of 18 , and separation of parents before 18 years of age (‘no’ vs. ‘yes’).Furthermore, family histories for alcohol abuse and psychiatric problems were assessed for the mother, father and siblings, as well as for paternal and maternal grandparents, uncles and aunts, based upon questions adopted from the Addiction Severity Index (ASI) Major Depression (MD) was assessed using the Major Depressive Inventory (ICD-10) – WHO-MDI Symptomatology of anti-social personality disorder was measured via the Mini International Neuropsychiatric Interview  and socio-demographic variables, including family history for the whole family. Unadjusted and adjusted odds ratios (OR) and 95% confidence intervals (95% CI) were calculated for all predictors. Adjusted values were assessed using all socio-demographic variables and family histories of alcohol and psychiatric problems for the whole family as covariates.The socio-demographic characteristics of the study sample are summarized in The 12-month prevalence of ADHD was 4.0% (n = 226). Using the four-strata classification system, no ADHD was reported in 81.3% of participants, while 14.7%, 3.4%, 0.6% of the participants were classified within strata II, III and IV, respectively, representing possible through definite cases of ADHD .More than half (50.8 to 65.3%) of the sample reported at least one ADHD symptom “rarely”, “sometimes”, “often” or “very often”. Symptoms of hyperactivity were reported slightly more frequently than the majority of inattention symptoms . Symptoms of inattention were reported as occurring “often” or “very often” in 0.7 to 9.0% men and hyperactivity symptoms in 1.9 to 13.6%. The frequencies of each symptom are shown in A positive association with ADHD was found for subject age, linguistic region, education level, and degree of financial autonomy. Older subjects and those from French-speaking regions were more likely to report ADHD symptoms than those who were younger or from German-speaking regions. For education, a trend (p<0.10) was observed, with a high school/university level education associated with a higher prevalence of ADHD than having completed primary school only; however, this association failed to achieve statistical significance after adjusting for all other variables. Additionally, compared to financial autonomy, ADHD was positively related to partial or complete financial dependency. However, when adjusting for all other variables, only complete financial dependency was significant. No significant difference between participants with and without ADHD was identified for residence or marital status.For childhood factors, logistic regression analysis revealed that subjects whose mothers had completed high school/university or just primary school were more likely to report ADHD than those whose mothers completed secondary school. Frequencies for these two former education levels were similar. Reporting a family history of alcohol or psychiatric problems was significantly associated with a higher prevalence of ADHD than not having such a history. Family affluence, living arrangement before the age of 18, and separation of parents before 18 years of age did not differ between those with and without ADHD. 2 = 114.94, p<.001; ASPD: X2 = 67.99, p<.001; alcohol abuse and dependence X2 = 58.90, p<.001). Similarly, a higher percentage of men in strata II, III and IV reported the presence of MD, ASPD, alcohol abuse and dependence than men allocated to stratum I. The rate of having at least one of these psychiatric disorders systematically increased from strata I to IV (Using the dichotomous classification (“no ADHD” vs. “ADHD”) 13.7% of our subjects with ADHD reported MD, 36.3% ASPD, 38.9% alcohol abuse, and 20.8% alcohol dependence. Rates for all these disorders were significantly higher among those with than those without ADHD , although this association failed to achieve statistical significance after adjusting for all other variables. Our results are clearly contrary to most previous reports, which constantly revealed a positive association between ADHD and lower education level In contrast to previous studies, in which problems with personal relationships were reported We did find that both a subject’s mother’s level of education and a family history of alcohol or psychiatric problems differed between those with and without adult ADHD. Mothers of participants with adult ADHD were more likely to have either a primary school or high school/university level education, while those without ADHD more often had mothers who had completed secondary school but not beyond. The finding that a low level of maternal education was associated with a greater prevalence of adult ADHD is consistent with the results of other studies, in which a higher risk for ADHD in children was observed in those with less-educated parents Family history of either alcohol or psychiatric problems also was positively associated with adult ADHD. In fact, a family history of psychiatric problems exhibited the highest odds ratio for ADHD of any variable, on logistic regression analysis. Once again, the strong genetic component of ADHD and the high comorbidity of ADHD with alcohol use disorders and other mental disorders could explain this association Consistent with previously-published findings The following limitations must be considered relating to the currently-presented study. First, women were not included in our sample. Although some study results suggest that men and women experience ADHD in a similar way Second, the prevalence of ADHD was assessed in the context of a population-based study that was not initially intended or designed to address ADHD-related questions. Therefore, prevalence only was assessed by means of self-report using the ASRS Screener and did not further include any confirmatory diagnostic assessment. This also was true for the assessment of MD, ASPD, alcohol abuse and alcohol dependence, as well as for family histories of alcohol and psychiatric problems. However, the assessment instruments we used are all well validated. Thus, we feel that our study provides a reasonable approximation of the prevalence of ADHD among young Swiss men. Nevertheless, it is important to note that, despite excellent concordance between the ASRS Screener and a clinical diagnosis of ADHD Third, the medical history for ADHD, mental disorders and family histories of alcohol and psychiatric problems, was not assessed; consequently, we do not know the clinical status of our study participants or whether they had received or continued to receive any treatment.Finally, since our data were collected at a single time point and not longitudinally, we cannot draw causal inferences.In summary, we found that roughly 4.0% of young Swiss men have ADHD, and that associations exist with other mental disorders, like major depression and alcohol abuse, as well as with family histories of alcohol and psychiatric problems. ADHD adversely affects work, health and interpersonal relationships. As such, clinicians and school professionals should remain alert to its existence and consequences in young males.


Attention deficit/hyperactivity disorder (ADHD) is a common disorder that often presents in childhood and is associated with increased healthcare resource use. The aims of this study were to characterise the epidemiology of diagnosed ADHD in the UK and determine the resource use and financial costs of care.For this retrospective, observational cohort study, patients newly diagnosed with ADHD between 1998 and 2010 were identified from the UK Clinical Practice Research Datalink (CPRD) and matched to a randomly drawn control group without a diagnosis of ADHD. The prevalence and incidence of diagnosed ADHD were calculated. Resource utilisation and corresponding financial costs post-diagnosis were estimated for general practice contacts, investigations, prescriptions, outpatient appointments, and inpatient admissions.Incidence of diagnosed ADHD (and percentage change using 1998 as a reference) increased from 6.9 per 100,000 population in 1998 to 12.2 per 100,000 (78%) in 2007 and then fell to 9.9 per 100,000 (44%) by 2009. The corresponding prevalence figures were 30.5, 88.9 (192%) and 81.5 (167%) per 100,000. Incidence and prevalence were higher in males than females. Mean annual total healthcare costs were higher for ADHD cases than controls .The prevalence of diagnosed ADHD in routine practice in the UK was notably lower than in previous reports, and both prevalence and incidence of diagnosed ADHD in primary care have fallen since 2007. Financial costs were more than four times higher in those with ADHD than in those without ADHD. Attention deficit/hyperactivity disorder (ADHD) is common and more likely to affect boys than girls, with an estimated prevalence in the UK of 3.6% and 0.9%, respectively, in children aged 5–15 years, using DSM-IV criteria ,3. ADHD In the UK, the National Institute for Health and Care Excellence (NICE) has recommended that diagnosis of ADHD and treatment initiation should be conducted within secondary care . When meThe aim of this retrospective, observational cohort study was to characterise the incidence and prevalence of diagnosed ADHD and to determine the corresponding resource use and financial cost of care for children, adolescents, and adults with ADHD compared with a matched control group over a 12-year period to 2010.Data were extracted from the CPRD  . CPRD coPatients were selected from CPRD if they had received two or more diagnoses for ADHD in their clinical history, or they had received at least one diagnosis of ADHD and at least one prescription for a medicine licensed for the management of ADHD. For cases where there was no prescription for an ADHD medication, the requirement of two or more diagnoses was used to avoid selecting for patients with only a provisional diagnosis recorded by the GP prior to assessment by a specialist. Under NICE guidelines, diagnosis should be made by a mental health specialist; therefore the second diagnosis is used to confirm that the patient has ADHD. A medicine used for the management of ADHD was defined as a product containing one of the following drugs: dexamfetamine, methylphenidate or atomoxetine. Pemoline   and modaCases were excluded from the analysis if they had a history of narcolepsy. In order to identify incident cases only, cases with less than six months’ “wash-in” for relevant parameters were also excluded .The number of person-years of people without ADHD was calculated by adding the number of days each patient had been present in the CPRD database for each specific year. Patients were included in the denominator until the earliest of their death date, transferred-out date, or ADHD presentation date. Patients who did not meet the selection criteria for the study were included in the denominator data.On the date of ADHD presentation, cases were included in the numerator portion of the incidence calculation for that specific year.The incidence of treated ADHD was calculated using the same method. For calculations of incidence by gender and age group only those patients of the appropriate age or gender were included in the numerator and denominator parts of the incidence calculation.The point prevalence of diagnosed ADHD was calculated each year by dividing the number of patients with ADHD on 1st July (mid-year point) of that year by the total number of patients registered in CPRD on that date.A patient was included as a prevalent case if they met the selection criteria for the study, their ADHD presentation date was prior to 1st July of the specific year, and the later of their last ADHD diagnosis or last prescription for an ADHD medication was after 1st of July of that year. However, in order to allow for an adequate washout period (more than 12 months), prevalence was only calculated from 1998 to 2009. A washout period was considered necessary as the chance of receiving a diagnosis for ADHD following the mid-year point reduces as the time between the mid-year point and the last collection date for the database becomes shorter.This was the total number of patients registered in CPRD on 1st July of the specific year.For calculations of prevalence by gender and age group only those patients of the appropriate age and gender were included in the numerator and denominator parts of the prevalence calculation.Resource use and costs were applied to the following areas of patient care: prescriptions, primary-care contacts, investigations, hospital admissions, and outpatient appointments. The aim was to calculate the overall cost of treating an individual with ADHD not just the cost of treating the ADHD itself. Annual costs for the first five years following the index date were estimated.Each prescription item listed in CPRD was attributed a net ingredient cost (NIC) from the corresponding year of the Prescription Cost Analysis (PCA) ,23. The Outpatient events were identified from CPRD’s consultation table if they had a consultation type indicative or suggestive of an outpatient appointment. The outpatient department and whether the consultation was a first or follow-up visit were used to allocate each appointment to an outpatient tariff .Investigations were identified, including both pathology and diagnostic services. Several reference sources were used to attribute a cost to these tests -29. LaboEach consultation was classified by consultation type  and staff type  and then assigned an average cost as listed in the Unit Cost of Health and Social Care 2010 from the Personal Social Services Research Unit (PSSRU) . Where aCPRD-linked HES records allowed us to cost inpatient admissions. From the care pathway outlined in the NICE guidelines for ADHD, we would not expect patients to be routinely admitted to hospital as a direct result of their ADHD . HoweverData from inpatient admissions recorded in HES were processed into Healthcare Resource Groups (HRGs) using HRG-4 grouper . The HRG3,229 cases with ADHD and 7,429 matched control patients were identified in CPRD Table . The meaIn 1998, the annual incidence of diagnosed ADHD across all ages was 6.9 cases per 100,000 population  of diagnosed ADHD increased from 30.5 per100k in 1998 to 88.9 per100k (192%) in 2007  healthcare costs for cases and controls over the five-year period were £1,196 and £337 for year 2, £1,148 and £316 for year 3, £1,126 and £325 for year 4, and £1,112 and £361 for year 5, respectively .A systematic review and meta-analysis characterising the worldwide prevalence of ADHD reported that the pooled prevalence was 5.3%, with significant variability . In the The figures reported here are similar to those reported in a government-sponsored audit of ADHD services in Scotland . In 2012We found that diagnosed cases of ADHD were more common in males than in females. Epidemiological studies have also reported a greater prevalence in males, with a male-to- female ratio of 2–3:1 . In adulIn our study, the diagnosed prevalence of ADHD in children age 6 – 17 years old increased from 192.4 to 506.4 per100k between 1998 and 2007. An increasing incidence rate was also observed between 1998 (39.3 per100k) and 2007 (79.0 per100k). An increase in the prevalence of ADHD has been reported in the USA between 1997 and 2007 ,46. SincA systematic review with meta-analysis has suggested that the prevalence of ADHD declines with age  . HoweverThe magnitude of the difference in annual mean costs was surprising. Prescription costs in year 1 were higher for cases compared to controls , largely due to the cost of ADHD medicines. NICE guidance indicates that drug treatment should be first line when ADHD is severe and can be considered for moderate ADHD and impairment in school-aged children and young adults when non-pharmacological approaches are unsuccessful . In adulNumerous studies investigating the healthcare costs associated with ADHD have been carried out in the USA, but their applicability to the UK NHS is questionable due to different patterns of service provision. Using information available for the UK, some estimates have been made of the cost of certain aspects of healthcare for ADHD at the population level. For health, social care, and educational services, it has been estimated that the NHS spends approximately £23 million on initial specialist assessment of ADHD in England and Wales and £14 million on follow-up care over one year . In addiThis study had inherent limitations. For cases where there was no prescription for an ADHD medication the requirement of two or more diagnoses was used in order to avoid selecting patients where the GP had recorded a provisional diagnosis of ADHD prior to referral for assessment by a specialist. However, this may have led to the exclusion of possible ADHD patients from the cost calculation and an underestimate of the incidence and prevalence rates. The care pathway for ADHD differs in comparison to many chronic conditions and will vary by site. Once the condition has been stabilised, GPs often prescribe drugs for ADHD under shared-care protocols. Prescriptions written in secondary care are not recorded in CPRD and could not be costed. Any underestimation of resource use and the related financial cost will disproportionately impact on the ADHD group and therefore the differences reported may underestimate the true difference. Those patients who are more difficult to stabilise may be less well recorded in CPRD as more of their healthcare may be provided in secondary care. In addition, our study index date may vary between patients from the date of first presentation to the GP, the date of referral back to the GP from secondary care, or the date of the first GP prescription for an ADHD medication. CPRD includes GP practices from all four UK regions and is therefore generalisable to the whole of the UK. On the other hand, the linked HES data is exclusively English, which could suggest that the healthcare cost estimates are generalisable to England only. However, the patients registered in the linked practices have been shown to be representative of the whole CPRD population .Regarding the estimation of prevalence, a patient had to have received a diagnosis of ADHD or a prescription for a medication for ADHD both prior to and after 1st July each year. Although a washout period of 12 months was applied, the time between the mid-year point and the last collection date for the database becomes shorter for the more recent years and this may have contributed to the reduction in prevalence rates since 2007. However, this method was selected since clinical records in CPRD cannot be used to determine when a patient stops experiencing ADHD. The calculation of incidence is sensitive to the method used to calculate the denominator. Although, for this study, patients need not necessarily have had contact with their general practice to be included in the patient-years estimate. An underestimation in the incidence and prevalence rates could also have occurred if diagnoses were not accurately recorded in CPRD. The validity of medical diagnoses in CPRD have been confirmed in several studies ,55. GPs In summary, the prevalence of diagnosed ADHD in the UK was notably lower than in reports that used screening. Costs in those with ADHD were more than four times higher than in those without ADHD.ADHD: Attention deficit/hyperactivity disorder; CPRD: Clinical Practice Research Datalink; DSM: Diagnostic and Statistical Manual of Mental Disorders; GP: General Practitioner; HRG: Healthcare Resource Group; NHS: National Health Service; NIC: Net ingredient cost; NICE: National Institute for Health and Care Excellence; PCA: Prescription Cost Analyses; PSSRU: Personal Social Services Research Unit.CLlM and CDP have been and SEH and SJJ are employed by Pharmatelligence, a research consultancy receiving funding from pharmaceutical companies. SEH is employed by Alliance Boots. CDP has consulted for the following manufacturers of diabetic pharmaceuticals: Astellas, BMS, Ferring, Lilly, Medtronic, Novo Nordisk, Sanofi-Aventis, and Wyeth. DC has received research grants from various health-related organisations, including European Union FP7, the National Institute for Health Research, Shire, and Vifor; consults for Shire; has been on advisory boards for Flynn Pharma, Janssen, Lilly, Medice, Novartis, Shire, and Vifor; has received royalties from Oxford University Press; and has received payment for lectures from Flynn Pharma, Janssen, Lilly, Shire, and Vifor. CJC has received research grants from various health-related organisations including Abbott, Astellas, Diabetes UK, the Engineering and Physical Sciences Research Council, the EASD, Ferring, GSK, Lilly, the Medical Research Council, Medtronic, MSD, the National Health Service, Pfizer, Sanofi-Aventis, Shire, and Wyeth; and consults for Amylin, Aryx, Astellas, Boehringer Ingelheim, BMS, Diabetes UK, Eisel, Ferring, GSK, Ipsen, Lilly, Medtronic, MSD, Pfizer, Sanofi-Aventis, Takeda, and Wyeth.The authors contributed the following: CJC conceived the study. CJC, CDP, CLlM, and SEH contributed to study design. SEH and CLlM analysed the data. SEH, CJC, DC, and CDP interpreted the data. SEH drafted the manuscript. SJJ provided data preparation and technical support. CJC, SEH, and DC were involved in the writing and reviewing of the report. CJC had overall responsibility for the study and is overall guarantor. JS and PH of Shire Development LLC provided comments on the outline and the initial draft of the manuscript, but the final content of this manuscript, the ultimate interpretation, and the decision to submit it for publication to the Child and Adolescent Psychiatry and Mental Health was made by the authors independently. All authors, external and internal, had full access to all of the data  in the study and can take responsibility for the integrity of the data and the accuracy of the data analysis. All authors read and approved the final manuscript.This research was funded by Shire Development LLC.Study Numbers.Click here for file


Attention deficit hyperactivity disorder (ADHD) symptoms can be difficult to treat. We previously reported that a 20-session brain-computer interface (BCI) attention training programme improved ADHD symptoms. Here, we investigated a new more intensive BCI-based attention training game system on 20 unmedicated ADHD children  with significant inattentive symptoms (combined and inattentive ADHD subtypes). This new system monitored attention through a head band with dry EEG sensors, which was used to drive a feed forward game. The system was calibrated for each user by measuring the EEG parameters during a Stroop task. Treatment consisted of an 8-week training comprising 24 sessions followed by 3 once-monthly booster training sessions. Following intervention, both parent-rated inattentive and hyperactive-impulsive symptoms on the ADHD Rating Scale showed significant improvement. At week 8, the mean improvement was −4.6 (5.9) and −4.7 (5.6) respectively for inattentive symptoms and hyperactive-impulsive symptoms (both p<0.01). Cohen’s d effect size for inattentive symptoms was large at 0.78 at week 8 and 0.84 at week 24 (post-boosters). Further analysis showed that the change in the EEG based BCI ADHD severity measure correlated with the change ADHD Rating Scale scores. The BCI-based attention training game system is a potential new treatment for ADHD.NCT01344044ClinicalTrials.gov  Attention deficit hyperactivity disorder (ADHD), a childhood onset developmental disorder, is a chronic condition that can extend into adulthood We previously reported the results of this approach in a small controlled trial In our first study we found that intervention with a training program involving the BCI-based attention training game system improved parent-reported inattentive symptoms. We also noted that behavioural improvement was sustained 3 months after the intensive 20-session intervention. The initial study was 10 weeks in duration with 2 sessions per week. It also involved the use of a very simple game and a tethered connection to a computer. Since then, we have developed a new version of the device that is simple, uses dry EEG electrodes and is connected by Bluetooth to the computer. A new game that could be calibrated based on the performance of the child was also developed. In addition it was important to understand who would be the right candidates to benefit from this approach.Therefore, the purpose of this study was to investigate ifThe new device with a new game and a more intensive new training schedule 3 sessions per week over 8 weeks was acceptable to patients.There is preliminary evidence of efficacy in improving ADHD symptoms.There is any clinical predictor of response.There is any EEG change as a function of response.The protocol for this trial and supporting CONSORT checklist are available as supporting information; see This study was approved by the ethics review boards of the Institute of Mental Health  and National Healthcare Group, Singapore . Written informed consent from parents and assent from children were obtained prior to study entry .This was a one-arm prospective study and we aimed to enroll 20 children, who would receive treatment with the BCI-based attention training program. The Consort Flow Diagram is shown in We invited the clinic’s psychiatrists to refer patients clinically diagnosed to have the inattentive or combined subtypes of ADHD based on the Diagnostic and Statistical Manual of Mental Disorders-Fourth Edition (DSM-IV) for the study. During the screening phase, parents completed the Diagnostic Interview Schedule for Children Version IV (DISC-IV) A subject was eligible for inclusion in the study only if all the following criteria applied at pre-study screening:Subject’s age was within the age range of 6–12 years old;Subject had never received treatment with stimulant medication or Atomoxetine;The subject should satisfy the following criteria for the diagnosis of ADHD:DSM-IV-TR criteria for ADHD, either the combined or inattentive subtype, based on clinical assessmentDiagnostic Interview Schedule for Children (DISC), as completed by the parents;Written Informed Consent from parent and Assent Form from child were both obtained;Subject and the parent/guardian were willing to comply with study procedures and were able to return to the clinic for scheduled visits.A subject was not eligible for inclusion in the study if any of the following criteria applied at pre-study screening:Present or history of medical treatment with stimulant medication and Atomoxetine;Co-morbid severe psychiatric condition or known sensori-neural deficit e.g. complete blindness or deafness (such that they could not play computer games);History of epileptic seizures;Known mental retardation (i.e. IQ 70 and below);Predominantly Hyperactive/impulsive subtype of ADHD (i.e. no predominant inattentive symptoms).We recruited 20 participants for the study, including 16 males and 4 females. The mean age was 7.80 . There were 17 Chinese, 2 Eurasians and one Malay. Fourteen children were diagnosed to have the combined subtype of ADHD based on C-DISC, and the other 6 had the inattentive subtype of ADHD.The BCI system consisted of a headband with mounted dry EEG sensors  that transmitted EEG readings to the computer through Bluetooth-enabled protocol. The headband was worn around the forehead, with a grounding reference electrode clipped to the earlobe see . Two dryThe possible effects of noise or artifacts such as extraocular activity on the EEG were considered and reduced in the BCI system. Since the noise and artifacts were generally uncorrelated with the attentiveness and in-attentiveness conditions, they were filtered out in our machine learning algorithm that extracted only discriminative features from EEG between the two conditions. To further reduce the electrooculography artifacts, we added a virtual EEG channel, which was the differential potential between Fp1 and Fp2. As a result, the system was not affected by normal eye movements.Prior to playing the video game (CogoLand), which was the main training activity, each participant underwent individual calibration using a colour Stroop task on the BCI-based attention training game system. During calibration, the participant performed the colour Stroop task to develop an individualized EEG profile of the optimal attentive state. The colour Stroop task required one to use the mouse to click on the name of the colour in which a word was spelt, and not the colour that the word spelt. The BCI-based attention training game system analyzed the critical EEG parameters during the correct attempts, compared to that when the participant was relaxing, to derive an individualized EEG pattern representing the participant’s most attentive state A computerized 3D graphic game, CogoLand was developed specifically as the training game. In CogoLand, the participant controlled an avatar via the signals detected by the EEG electrodes. This was computed into a BCI ADHD Severity Measure, or BASM (see next section for details of its computation). The BASM was then transformed to a score ranging from 0 (minimum attention) to 100 (maximum attention), which was reflected on the computer screen. The participant would hence need to ‘concentrate’ in order to move the avatar, which would move at a speed proportional to the participant’s attention level as measured by the BCI-based attention training game. The ‘higher’ the concentration level of the participant was, the higher would be the speed of the avatar’s movement. There were three difficulty levels in CogoLand. The main goal of the first level was to make the avatar run around an island in the shortest time possible. The next two levels had an additional component where the child needed to collect a series of fruits floating in the air as the avatar navigated through a pre-determined route in a colorful town. The child would use a specific key on the keyboard to make the avatar jump to collect the fruits which would appear along the journey. The child was asked to collect as many fruits as possible within a given timeframe, after which the number of fruits collected was entered into a personal logbook. At the third level the child had to collect the fruits in an order presented on the screen. A short break was allowed between attempts. For each training session, the individual would complete 30 minutes of training, including the breaks.All raw EEG data obtained during calibration with the Stroop task was analyzed by the BCI system. It was screened to detect any abnormality in the EEG recordings, such as disconnected electrodes and saturated digital samples. Any abnormal EEG readings, including the readings within two seconds from the occurrence of the abnormality were excluded from analysis. The system then extracted discriminative rhythmic power features from the screened EEG using spatial-spectral filtering.The system examined an array of 8 frequency bands, continuously covering from 4 Hz to 30 Hz. This arrangement not only covered traditional EEG bands from theta to beta, but also had a finer grid of frequency bands. Band powers were computed using the following procedure. First, the EEG data was segmented into a continuous sequence of 2-second long time blocks; in each block, power spectrum was computed using a 256-point Fast-Fourier-Transform technique; a specific band power was calculated as the sum of the spectrum powers at all the discrete frequencies in the band; and the specific band power was the average value of the band power over the time blocks. The band power was calculated for each EEG channel separately, in addition to the differential potential between the two channels. The BCI system then selected the band power features for maximizing the separation between attentive and inattentive states according to the information theory. A regression function would be applied by the BCI system to transform the selected features into a BASM score, which represented the severity of the inattentive symptoms of ADHD at the time of EEG recording. The BASM score was inversely proportional to the severity of the inattentive symptoms and the lower the BASM score, the more inattentive the individual was.We used this BCI-based attention training game system for our intervention program (the BCI-based attention training program), which comprised of an intensive phase with 3 training sessions weekly for 8 weeks, followed by a maintenance phase with once-monthly booster training sessions for 3 consecutive months. At the end of every alternate training session starting from the second session, each participant would complete 2 short English and Mathematic worksheets consisting of multiple choice type questions on the computer. These worksheets were appropriate to their educational level and took approximately 10 minutes to complete. Each participant was instructed to concentrate like when they were playing the games, and their EEG was monitored during this period. Treatment was administered by 3 therapists trained to fit the headband and administer the BCI-based training program. All the therapists had obtained at least a graduate degree in psychology, and they administered treatment according to a standardized treatment protocol. Calibration was done at weeks 0, 4 and 8.th edition (ADHD-RS) At baseline, parents completed the 18-question ADHD Rating Scale, 4There were 17 (85%) subjects who completed the entire study. One boy dropped out before 4 weeks, as the parent felt there was no improvement in the child’s behaviour. Two other boys dropped out between 4 and 8 weeks due to difficulty adhering to the treatment schedule.We conducted Intention-To-Treat (ITT) analyses on the results and excluded the subject who dropped out before week 4 as there was no follow up data at all. We carried forward the last available observation  where appropriate. Multiple imputations using Markov chain Monte Carlo and a per protocol analysis including only subjects who completed the study were also conducted and the results did not show much difference from that based on the last observation carried forward method.There was no statistically significant change in parental observation of inattentive and hyperactive-impulsive symptoms on the ADHD-RS at 20 weeks compared to 8 weeks, or at 24 weeks compared to 20 weeks. When examining the ratings at 24 weeks, compared to the baseline score, there was significant improvement in parent-rated inattentive and hyperactive-impulsive symptoms (mean changes = −5.0 (5.8) and −5.7 (5.1) respectively and p≤0.01 for both IA and HI). These results appear to suggest that monthly booster training for 3 consecutive months after an intensive 8-week training did not significantly improve inattentive or hyperactive-impulsive symptoms further. The behavioural benefits from the intensive training at 8 weeks were sustained at 24 weeks. The child’s age and gender did not have any statistically significant effect on ADHD-RS scores in this study.We used EEG data from the calibration/re-calibration sessions (at week 0 and 20) and examined the BASM scores. We had to exclude the 3 participants who dropped out before week 8 and 3 other patients who had missing EEG data at Week 20. Thus, we analyzed a total of 14 participants from the original 20 recruited. When comparing the BASM scores at Week 0 and at Week 20, there was an increase in the mean score (standard deviation) from 60.9 (81.0) to 96.9 (64.7), although paired t-test showed that the change was not statistically significant (mean change = 32.5 (60.8), p = 0.067).Linear regressions showed that baseline IA, HI and COM scores statistically significantly predicted their respective changes of ADHD rating scale scores from week 0 to 8 (β (SE) = −0.7 (0.2), −0.9 (0.3) and −0.9 (0.3) respectively and p = 0.013, 0.008 and 0.007 respectively). Thus, a higher score on the ADHD-RS at baseline predicts greater improvement at week 8. We investigated the possible correlations between the change in BASM scores and the changes in scores on ADHD rating scale from Week 0 to Week 20. Correlation analyses performed in The intervention was also well tolerated. In this trial, the main side effect reported was headache, which affected two of the participants. The severity of the headache was reported to be mild and did not stop them from continuing with treatment.The present study evaluated the new version of the BCI-based attention training program, which included dry sensors and blue tooth technology in place of EEG leads with a game CogoLand, in the treatment of combined and inattentive subtypes of ADHD. Our results show that an 8-week intervention significantly improved inattentive symptoms of ADHD, based on a behavioural rating scale by parents. Among children with the combined subtype of ADHD, parents also reported a significant improvement in their hyperactive-impulsive symptoms on the ADHD Rating Scale. When these children received monthly training sessions subsequently, the behavioural improvements were sustained but did not further improve. Those with more severe symptoms were also the ones who showed greater improvement.This built upon our initial report on the training program’s positive effects on treating ADHD symptoms. Although shown to improve inattentive symptoms more than hyperactive-impulsive symptoms then, we now found significant treatment effects for both inattentive and hyperactive-impulsive symptoms of ADHD. It is possible that non-specific factors like behavioural contingencies, self efficacy and a structured training environment could have contributed to improvement in the hyperactive-impulsive symptoms. Children with both inattentive and combined subtypes, which are far commoner than the hyperactive-impulsive subtype, appear to improve with treatment.Additionally we also found that the change in BASM score correlated with the change in behavioural rating score by parents. This provided some evidence that the improvement with training, as reflected by the BASM score, might explain the improved ADHD symptoms reported by parents. The BASM score also appeared to be a good surrogate marker for observed inattentive behaviour. In many ways this is a refinement from previous work that looked at specific EEG bands. Neurophysiological studies have previously shown that children with ADHD exhibit specific patterns on the electroencephalogram (EEG) and this has been utilized clinically to diagnose, treat and even predict response to treatment with medication BCI-based attention training game system can offer several advantages over current evidence-based treatment options offered in most clinical practices. It has less adverse events compared to medication. Unlike behavioural management or parent training, there is no need for regular clinic visits which can be inconvenient. The system potential utility adds to the growing research in an area that was a precursor to this approach namely neurofeedback. Computer-based neurofeedback attention training programmes have been shown to improve inattentive symptoms There are some important limitations to our present study. This is an uncontrolled open-label trial and thus the parents who completed the behavioural rating scale were not blinded. This could have resulted in an exaggerated treatment effect. Unfortunately the non-response rate from the children’s schoolteachers was too high for the results to be interpreted meaningfully. A well-designed randomized controlled trial is needed to evaluate the efficacy of BCI-based attention training program in treating ADHD.Brain computer interface based attention training game can be a potential new treatment for ADHD. A randomized controlled trial to study the efficacy of this intervention and the neural mechanisms underlying the behavioral improvements is currently underway. It represents a novel treatment modality for ADHD, which not only has the potential for being used in combination with present evidence-based treatment, but also uniquely in a non-clinical setting.Protocol S1Trial protocol.(PDF)Click here for additional data file.Checklist S1CONSORT checklist.(DOC)Click here for additional data file.


It is well understood that to maximise performance in sport it is important to optimise all possible variables. Headache is a very common symptom, while migraine affects between 10-15% of the population. Although athletes are frequently subject to large numbers of potential migraine triggers , there are relatively little data examining the impact of headache conditions on elite athletes.In order to investigate the prevalence and impact of headache on the performance of elite athletes we are undertaking a joint study together with the Faculty of Sports and Exercise Medicine UK.A questionnaire has been formulated together with the British Association for the Study of Headache (BASH), and the Faulty of Sports and Exercise Medicine. It will be submitted to various professional sports and athletic associations. To date the British Lawn Tennis Association, British Horse Racing Authority and Football Association (UK) have been approached.At present, preliminary results are available from 30 questionnaires recently received via the British Lawn Tennis Association and British Horse Racing Authority.57% (17/30) of respondents reported that headaches limited optimal performance in their sport , although only one respondent fulfilled ID migraine criteria.Of headache sufferers, 10% 2/17) stated that headaches were problematic before or during major competitions, 41% (7/17) did not have an effective method to manage their headaches and 35% (6/17) stated they would welcome more help to manage their headaches.[/17 stateThese preliminary results showed a significant proportion of elite athlete respondents suffer performance limiting headaches. While further data should quantify this more accurately, headache may be an under-addressed issue in elite athletes. Healthcare professionals working in sports medicine may find that paying greater attention to the impact and management of headache disorders would improve the performance of elite athletes under their care.


Attention Deficit/Hyperactivity Disorder (ADHD) is associated with an increased risk of co-existing substance abuse. The Swedish legislation on compulsory healthcare can be applied to persons with severe substance abuse who can be treated involuntarily during a period of six months. This context enables a reliable clinical assessment of ADHD in individuals with severe substance use disorder (SUD).In the context of compulsory care for individuals with severe SUD, male patients were assessed for ADHD, co-morbid psychiatric symptoms, psychosocial background, treatment history, and cognition. The data from the ADHD/SUD group (n = 60) was compared with data from (1) a group of individuals with severe substance abuse without known ADHD , as well as (2) a group with ADHD from an outpatient psychiatric clinic .Compared to the general SUD group in compulsory care, the ADHD/SUD group had already been significantly more often in compulsory care during childhood or adolescence, as well as imprisoned more often as adults. The most common preferred abused substance in the ADHD/SUD group was stimulant drugs, while alcohol and benzodiazepine abuse was more usual in the general SUD group. Compared to the ADHD/Psych group, the ADHD/SUD group reported more ADHD symptoms during childhood and performed poorer on all tests of general intellectual ability and executive functions.The clinical characteristics of the ADHD/SUD group differed from those of both the SUD group and the ADHD/Psych group in several respects, indicating that ADHD in combination with SUD is a particularly disabling condition. The combination of severe substance abuse, poor general cognitive ability, severe psychosocial problems, including indications of antisocial behaviour, and other co-existing psychiatric conditions should be considered in treatment planning for adults with ADHD and SUD. Attention-Deficit/Hyperactivity Disorder (ADHD) is an early-onset neurodevelopmental disorder characterized by deficiencies in impulse control, regulation of activity level, and attention. ADHD also frequently involves executive dysfunctions, such as problems of planning, organization, getting started, and completing activities. While the prevalence of ADHD in the population is about 1.2 – 7.3% .The increased risk for developing substance abuse among individuals with ADHD may be related to the core symptoms of ADHD, such as impulsivity, as well as associated problems in ADHD, such as weakness in executive regulation of affects and motivation. Adults with ADHD also report high levels of stress in everyday life and poor coping ability  and subsThe Law on Care of Alcoholics and Drug Abusers (LVM) is one of four laws governing involuntary care in Sweden. The National Board of Institutional Care (SiS) is the authority responsible for compulsory treatment of adults with severe substance abuse, according to the LVM, as well as for compulsory care of children and adolescents with severe social problems such as substance abuse and antisocial behaviour, according to the law on Care of Young Persons (LVU).In Sweden, approximately 1000 individuals per year are sentenced to compulsory care for severe substance abuse in accordance with the LVM. There are more than 300 treatment sites that are distributed among 11 institutions around the country. In recent years, assessments of neurodevelopmental disorders have frequently been requested during the compulsory care under LVM. In many cases, it has not been possible to perform this type of assessment due to an on-going substance abuse.In the scientific literature, adults with ADHD have been clinically characterized in psychiatric and forensic  settingsThe objective of the present study is a clinical characterization of patients with ADHD and severe substance abuse disorder in a compulsory care context. Our aim is to increase the clinical understanding of this patient group in order to facilitate adjustment of treatment for this clinically challenging group. In order to characterize this group, a comparison has been made with two other groups: a group of patients with SUD in compulsory care without a known ADHD and a group of individuals with ADHD from a psychiatric outpatient setting.The assessment of the study group was made between the years 2004 and 2008 at an SiS institution, SiS LVM Institution Hornö, located in Enköping, Sweden. The patient target of the SiS Institution Hornö is adult males who, in addition to substance abuse, are violent and/or may have other severe psychiatric co-morbidity. The patients come from different municipalities in Sweden and have been placed at an institution of a central unit of the National Board of Institutional Care. The SiS LVM Institution Hornö has conducted clinical assessments for many years in order to obtain data for individualized treatment planning, including treatment for ADHD. The voluntary assessments are conducted when requested by the patient’s social worker, the patient himself or the ward staff.Figure In order to characterize the ADHD/SUD group in compulsory care, we used two control groups. First, a general SUD group in compulsory care without known ADHD diagnosis and second, a group with ADHD without severe SUD in voluntary outpatient psychiatric care (ADHD/Psych group). Data for these control groups were extracted as follow.In order to compare the characteristics of the combined ADHD/SUD group with the general SUD population in involuntary care, we used unidentified data from the SiS internal database , matched for age and years of assessment and covering the majority of the treated patients. During the time period for current study (2004–2008), a total of 1968 male clients were registered in DOK database. We selected data on 120 male clients without known ADHD diagnosis matched with the ADHD/SUD group from Hornö Institution for age and year of admission.p = .002).For comparison of the ADHD/SUD group the SiS Institution from Hornö with individuals with ADHD in voluntary psychiatric outpatient care, we used data on patients assessed at an outpatient tertiary psychiatric clinic, the Neuropsychiatric Unit Karolinska, Psychiatry Northwest, Stockholm, Sweden. The data on the ADHD/Psych group were extracted from an anonymous database, and the inclusion/matching criteria were sex , age range (19 to 46 years), and year of diagnostic assessment (2004–2008). One hundred seven individuals met these criteria and were all included in the ADHD/Psych group. The ADHD/Psych group had a mean age of 29.6 years (SD = 7.28) and were thus somewhat older than the ADHD/SUD group . The difference in age was statistically significant, as indicated by Student’s t-test .None of the study groups  were originally recruited to a research study but the assessments were performed as an ordinary clinical work. Thus, the study had a retrospective design and the participants did not give their written informed consents. The study was approved by the Regional Ethics Committee of Stockholm (2009/823-31/4 and 42-790-2012).In compulsory care for SUD, interviews with the clients are conducted on admission, discharge and one year after discharge. The semi-structured interviews, which are voluntary, are conducted by treatment staff at the SiS institutions for compulsory treatment of severe SUD. The data from the interviews are stored in the SiS evaluation and documentation system, the DOK database, which provides a large amount of information intended to guide treatment planning, as well as to provide a basis for research, operational planning, and follow-up.Not all clients in the study group had had the DOK interviews and, in these cases, the background data were studied during the clinical ADHD assessment (see below).The assessment of the general SUD group without a known ADHD (n = 120) was obtained entirely from an anonymous database comprising all DOK-interviewed clients.semi-structured clinical interview based on the Diagnostic and Statistical Manual of Mental disorders- Fourth Edition  = 3.21, p = .002, Cohen’s d = .62).Participants in the ADHD/SUD group reported significantly more ADHD symptoms in childhood as measured with WURS-25  compared to the ADHD/Psych group  . Similarly, further analyses of verbal IQ and non-verbal/performance IQ showed poorer results for the ADHD/SUD group: verbal IQ , non-verbal/performance IQ . Analyses on the level of the four indexes of the WAIS-III showed similar pattern of results, i.e. the ADHD/SUD group performed poorer in all indexes: verbal comprehension index, VCI ; perceptual organization index, POI ; working memory index, WMI ; processing speed index, PSI . On controlling for FSIQ in an ANCOVA, the group differences in the working memory index (WMI) and speed of processing index (PSI) no longer reached statistical significance , indicating that there was no specific effect on EF in the ADHD/SUD group.Compared to the ADHD/Psych group, the ADHD/SUD group was found to have significantly poorer results in the full-scale IQ , the ADHD/SUD group showed a more severe childhood symptomatology and poorer general cognitive ability.Parental divorce and other unfavourable growing-up conditions, such as substance abuse and psychiatric disorders in parents, were common in both the ADHD/SUD group and the general SUD group. However, early separation of parents was more than twice as frequent in the ADHD/SUD group. Adverse life events during childhood, such as parental psychiatric disorders and substance abuse, have previously been reported in both individuals with ADHD ,8,15 andBoth the ADHD/SUD group and the general SUD group had a low educational level and the two groups did not differ largely from each other. However, the ADHD/SUD group had been subjected to a significantly higher degree to compulsory care (LVU) in childhood, which always includes a compulsory 9-year primary school education. In addition to the individuals being subjected to compulsory care during childhood, 37.7% of the ADHD/SUD group had received special education in primary school. Thus, in total, 80% of the ADHD/SUD group had received support to cope with school demands. Remarkably, only 13 of the 60 individuals in the ADHD/SUD group (21.7%) had a previous ADHD diagnosis at admission to SiS Institution Hornö.Large proportions of both the ADHD/SUD group and the general SUD group had limited work experience, which was to be expected, bearing in mind the severe substance use disorder in both groups. However, we also observed a statistical trend in the ADHD/SUD group including several individuals with less than six months of work experience.Antisocial behaviour was a distinguishing characteristic of the ADHD/SUD group, which not only had been subjected to a higher degree of compulsory care in childhood, but also imprisonment during adulthood, as compared to the general SUD group in compulsory care. The frequent co-existence of ADHD and conduct disorder (CD), oppositional defiant disorder (ODD), and adult antisocial behaviour has been reported previously -22 and iPsychiatric co-morbidity is common in adults with ADHD ,15,33-35In a study of longer-term prison inmates with ADHD, all of whom had a diagnosis of substance abuse disorder, more than 70% preferred psycho-stimulants . It has The comparison between the ADHD/SUD group and the ADHD/Psych group indicated medium-to-large differences in all measured parameters. The retrospective self-rating symptoms of ADHD during childhood were significantly higher and the estimated IQ was significantly lower in the ADHD/SUD group than in the ADHD/Psych group. In previous studies, IQ on a group level has been found to be lower in ADHD individuals than in the general population ,40,41. IThe negative impact of various types of substance abuse on memory and executive functions has been reported frequently -49 and iAltogether, the findings suggest that undiagnosed ADHD, especially in combination with antisocial behaviour and poor cognitive functions, constitute a high risk for the development of an extensive clinical burden, which, in turn, is associated with high risks, such as accidents, drug overdoses, and mortality, as well as family burdens and high care costs for society -52.In many respects, the ADHD/SUD group and the general SUD group, showed similar clinical impairments and did not differ in socio-demographic background which could implicate need of intensive clinical intervention in both groups to reduce their burden of harm. However, findings in the current study also indicate that clients with ADHD in combination with SUD at a group level differ in some essential respects, both from the general LVM population with SUD and the ADHD/Psych group. This may implicate different treatment strategies concerning pharmacological and non-pharmacological treatment of ADHD with diverse comorbidities. Moreover, even ADHD-specific treatments, such as structured behaviour therapy for adults with ADHD , probablThe present study has some limitations that may have had some impact on the observed results. One limitation is that the number of undiagnosed ADHD patients in the general SUD group was unknown. Bearing in mind the high prevalence of ADHD in substance abusers , it is pIn summary, the ADHD/SUD group exhibited a substantial and complex symptomatology with severe substance abuse and lifetime psychosocial problems, including early and persistent antisocial behaviour, as well as psychiatric co-morbidity and poor general cognitive ability. According to the findings, a clinical implication is that the total clinical burden of adults with ADHD and co-existing SUD should be identified and considered in treatment planning in terms of risk factors, treatment content, and the context and duration of treatment, as well as the short and long-term treatment goals.The authors declare that they have no competing interest.BBM, JJ and TH designed the study. BBM and TH performed the statistical analysis. TH drew the figures. All authors contributed to the interpretation of the results. BBM wrote the first draft, supervised by TH and JJ. All authors read and commented on the manuscript, as well as approved the final manuscript.The pre-publication history for this paper can be accessed here:http://www.biomedcentral.com/1471-244X/13/336/prepub


We hypothesized that Amazonian people have developed divergent bitter manioc cultivation systems as adaptations to the properties of different soils. We compared bitter manioc cultivation in two nutrient-rich and two nutrient-poor soils, along the middle Madeira River in Central Amazonia. We interviewed 249 farmers in 6 localities, sampled their manioc fields, and carried out genetic analysis of bitter manioc landraces. While cultivation in the two richer soils at different localities was characterized by fast-maturing, low-starch manioc landraces, with shorter cropping periods and shorter fallows, the predominant manioc landraces in these soils were generally not genetically similar. Rather, predominant landraces in each of these two fertile soils have emerged from separate selective trajectories which produced landraces that converged for fast-maturing low-starch traits adapted to intensified swidden systems in fertile soils. This contrasts with the more extensive cultivation systems found in the two poorer soils at different localities, characterized by the prevalence of slow-maturing high-starch landraces, longer cropping periods and longer fallows, typical of previous studies. Farmers plant different assemblages of bitter manioc landraces in different soils and the most popular landraces were shown to exhibit significantly different yields when planted in different soils. Farmers have selected different sets of landraces with different perceived agronomic characteristics, along with different fallow lengths, as adaptations to the specific properties of each agroecological micro-environment. These findings open up new avenues for research and debate concerning the origins, evolution, history and contemporary cultivation of bitter manioc in Amazonia and beyond.Shifting cultivation in the humid tropics is incredibly diverse, yet research tends to focus on one type: long-fallow shifting cultivation. While it is a typical adaptation to the highly-weathered nutrient-poor soils of the Amazonian  Hence, this form of land-use is spatially (fields must shift frequently) and temporally  extensive. Extensive systems are widely held to be well adapted to such soils because a nutrient flush provided by the burning of secondary or mature forest is used for a single cropping period, before swidden fields are left to fallow in order to restore fertility via the growth of secondary forest terra firme today represent an optimal adaptation to a low productivity environment. While their theories have long since gone out of fashion Manihot esculenta Crantz) continue to focus almost exclusively on LFSC practiced by current Native Amazonian populations terra firme environments.Shifting cultivation has been a predominant mode of traditional agriculture in the rainforests of the lowland Neotropics In Amazonia, however, the most populated areas – both today and in the late pre-Columbian period – are along major white-water rivers, such as the Solimões, Amazon and Madeira, all of which have nutrient-rich floodplain soils used for agriculture and adjacent paleo-floodplains that are somewhat more nutrient-rich than the typical Oxisols and Ultisols terra firme areas that were safe from flooding but located on less fertile soils Denevan recognized that large scale settlements could not have been supported exclusively by seasonal floodplain cultivation, given the riskiness of producing food in areas subjected to floods. He proposed that settlements would preferentially be located on bluffs along the river margins, allowing the exploitation of both the fertile floodplain zones and the These historical arguments point to the possibility that local people may also intensify shifting cultivation when circumstances permit today. Fertile soils, such as ADE and floodplain soils, provide farmers with the opportunity to intensify shifting cultivation, increasing both crop productivity and frequency of cultivation Manioc landraces are classified as either bitter or sweet depending on cyanogenic glucoside (CG) content. In Central Amazonia, bitter manioc is the staple crop today, whilst sweet manioc is only of secondary importance Manioc is vegetatively propagated via stem cuttings, which grow into plants that are genetically identical to the mature plants from which they were cut. However, manioc retains its ability to reproduce sexually and produces seeds that lie dormant in fallow vegetation This article examines the hypothesis that contemporary Amazonian people have developed divergent bitter manioc cultivation systems as adaptations to the properties of different soils in the landscapes that they inhabit. We test this hypothesis by comparing swidden systems in fertile (ADE and floodplain) and infertile (Oxisols and Ultisols) soils with respect to their assemblages of manioc landraces, the performance (from the farmer's point of view) and productivity of the most common landraces in different soils, along with the genetic relationships between the most common landraces, and length of fallow periods. Hence, we will examine both the adaptations of manioc landraces and of swidden-fallow systems. In earlier publications i) perceive that certain landraces yield better in certain soils , but that this informed their ii) selection of different landraces for planting in different soils (the basis for the la index), and iii) that fertile soils (ADE/floodplain) could be farmed with much shorter fallow periods than infertile soils .In the preliminary stage of research we conducted multi-sited participant observation in numerous communities of the study region . Subsequterra firme manioc farmers in and around the Brazilian Sustainable Development Reserves of Mamirauá and Amanã, close to the town of Tefé on the middle Solimões River Most intriguingly, however, was the finding that farmers expressed these perceptions and behaviors in the form of a local theory of strength and weakness . Alterra firme are planted in more than one type of soil: among the 29 landraces cultivated in ADE, 18 (62%) are also planted in Ultisols and 19 (65.5%) in Oxisols. Ultisols and Oxisols shared 75% (15) of their landraces. On the other hand, most of the landraces that occurred in the floodplains  only occurred in this environment, with only four landraces shared with other types of soil . The number of landraces cultivated in each village varied between 5 (Verdum) and 21 (Vista Alegre), and tended to be lower in floodplain villages  than villages located on the terra firme , principally because villages on the terra firme have access to more than one type of soil . The average number of landraces cultivated in each manioc field was similar among the different types of soil   .terra firme along the middle Madeira is quite low, although higher than what Grenand reported along the Cuieiras River near Manaus (six) terra firme, as pointed out by Denevan Along the Upper Negro River, communities commonly have 60 to 89 landraces, somewhat higher when compared to other local communities in Amazonia and in the Atlantic Forest in Brazil 53–58; . The divThe composition of manioc landraces in fields on different types of soil is significantly different, which is shown both in the general model  and also in all possible pairwise comparisons (six) between the four different soil types  . In genepri) for each landrace in each type of soil on the terra firme was calculated. Most of the landraces mentioned by the farmers in the interviews in all three soils on the terra firme  have a very low pri score, either because they are rarely cited in that specific soil or because farmers do not rank them among the best performers in that soil  and their performance (pri) in the soils . This high degree of correlation between pri and la supports the notion that farmers' planting behavior is shaped by their perceptions of the performance of different landraces in different types of soil. While this pattern is common and has been mentioned elsewhere  interviewed simply ignore or weed out the seedlings, while others  take cuttings from mature seedlings and plant them separately  incorporated as a sub-landrace of an existing landrace (such as Jabuti-Preto); iii) named as a combination of two landraces (such as Jabuti-Arroz); or iv) established as a new landrace with a different name.At the six localities examined in this study, both the incorporation of seedlings into pre-existing landraces and the creation of new landraces from seedlings are relatively common practices. Farmers recognize that seedlings often appear in the newly burnt fields parately . When maOH) higher than expected heterozygosities (Arroz from ADE at Barreira do Capanã had an observed heterozygosity of 0.495 and 5 different multi-locus genotypes (MLGs) in the 20 individuals examined. The landraces Jabuti from Oxisols and Tartaruga from floodplain had 7 and 6 different MLGs, and OH of 0.567 and 0.707, respectively. The number of MLGs reflects either the incorporation of seedlings or the unintentional “mixing” of landraces , both of which contribute to increasing heterozygosity. Incorporation of seedlings into recognized landraces increases intra-landrace heterogeneity, because farmers tend to select the largest and healthiest volunteers, which tend to be the most heterozygous All the landraces analyzed with microsatellite markers had observed heterozygosities  contribute to the presence of these practices and associated knowledge in different parts of Amazonia. We conjecture that selection for agronomic performance would be more likely to emerge amongst people inhabiting areas with greater heterogeneity of soil types.The findings of Boster, Heckler and Zent, and Salick et al. explain the persistence of the notion that farmer identification and selection of manioc landraces is weakly associated with agronomic performance. Our findings, however, when combined with those of Kensinger and Wilson, support the conclusion that the way in which terra firme, intentional selection of certain landraces for cultivation in certain soils was demonstrated by the close relationship between Performance Ranking Index and Landrace Area for landraces in different soil types. These findings suggest that the local theory revolving around metaphors of strength and weakness may represent a cognitive manifestation of adaptive farming behavior: a way to express in simple terms local knowledge of the relationship between different sets of bitter manioc landrace traits and soil properties and fallow stages. Although landraces grown in ADE and the floodplain share similar phenotypical characteristics, specifically fast maturation and low starch content, and are both described as “weak” by farmers, these groups of landraces were not genetically more related to each other, as we had predicted from ethnobotanical observation. Rather, the landraces grown in upland soils (ADE and Oxisols/Ultisols) are more related to each other and genetically differentiated from floodplain landraces. For landraces cultivated in the floodplain and in ADE, the selection for convergent adaptive traits appears to be associated with the similar ecological adaptations to nutrient-rich soils and short periods for rapid growth and yield before stress. The stresses are quite different, however: floods in the floodplain and enhanced weed pressure in ADE. Nonetheless, they yield convergent adaptive results.We examined manioc cultivation in four different soil types at six localities, and found that farmers plant different assemblages of bitter manioc landraces in different soils and that shorter fallow lengths were strongly associated with more fertile soils. Most popular landraces were shown to exhibit significantly different yields when planted in different soils. From this we can infer that farmers have selected different sets of landraces with different perceived agronomic characteristics, along with different fallow lengths, as adaptations to the specific properties of each agroecological micro-environment. On the terra firme) and the flood pulse (floodplain); alternatively, owing to their greater fertility, it may be that the floodplain and ADE are the only places that offer the opportunity to produce food and/or money in a shorter time period – and this could also be a driver for the selection of these common traits.If the similar ecological adaptations observed for ADE and floodplain landraces are outcomes of adaptive convergence of traits directed by farmer's selection, what drives that selection? On ADE, farmer selection for fast maturing landraces coupled with a reduction in fallow periods is likely to be driven by population pressure and permitted by ADE's high nutrient availability. When ADE is cultivated at Barro Alto and Água Azul, where population pressure exerts more of an influence, the most intensive swidden-fallow systems were found . These iOur findings broaden our understanding of the diversity of bitter manioc swidden-fallow systems in contemporary Amazonia, and allow some ethnographic projection. Firstly, the intensive short-fallow shifting cultivation in the floodplain and on bluffs with ADE that we reported along the middle Madeira are clearly modern analogs of Denevan's terra firme, and in fertile ADE and floodplain soils. Amazonian Dark Earths are easily recognizable by their very dark brown or black coloring, high fertility, and pottery shards. The other terra firme soils were classified in the field according to local ethnopedological knowledge and physical properties . It was found that the local ethnopedological category “barro” (clay), recognized by its red/yellow coloring and high clay content in the A horizon, is broadly coterminous with Oxisols, while the local category “areia” (sand), recognized by dark brown, grey or black coloring and highly friable and “sandy”  A horizon is broadly coterminous with Ultisols vazante; ii) the high floodplain, known as the restinga; iii) and the back-swamp area, known as the cacaia  were selected for semi-structured quantitative interviews on bitter manioc cultivation on ADE, Oxisols and Ultisols: Barro Alto, Barreira do Capanã/Boa Vista, the Água Azul Coast, and Vista Alegre  granted by the Brazilian National Research Council (CNPq). Four a Alegre . These la Alegre :184–85. JAF conducted extensive participant observation in all communities of the study area prior to and during subsequent quantitative work (from September 2006 to March 2008), in order to build rapport and open up areas of interest that cannot be gleaned from close reading of the literature la – see below) in fields on four soil types , b) perceptions of relative performance (performance ranking index – pri – see below) of the same landraces in the three different terra firme soils, c) fallow lengths, and d) incorporation of seedlings. In order to test if fields on different soils exhibit different compositions of landraces, data on la were ordered through a Non-Metric Multidimensional Scaling (NMDS) based on the Bray-Curtis dissimilarity, followed by non-parametric multivariate analyses of variance  the area occupied by each manioc landrace  of each landrace they planted in their fields. We asked each farmer (a) which landraces he/she cultivated, (b) how many bundles of each landrace he had planted in his/her current manioc field and (c) how big was his/her field. Using this information we calculated the area occupied by each landrace in each field (la) through the formula:la is the landrace area index, nbv is the number of bundles of a given landrace planted in a given field, nbT is the total number of bundles planted in that field, and arf is the area of the field. Since we did not observe differences in the spacing used to plant the landraces, we regard the area occupied by each landrace (la) as a good estimator of the abundance of each landrace in the field. When all landraces are taken into account, we interpret this data as the varietal composition of the fields. We collected data on fallow lengths by asking each farmer how old the fallow was that he/she had cleared in order to establish the field. Data for the calculation of la and on fallow lengths were collected with 249 farmers at all six localities, of which 190 farmers on the terra firme and 59 on the floodplain.In order to identify the different landraces cultivated and quantify their abundance in the fields, we relied on the local nomenclature for the landraces and on numerical estimates provided by each farmer, using a local unit commonly used for quantifying manioc stem cuttings. In general, farmers along the middle Madeira recall the amount of each landrace they plant in terms of the number of bundles (“terra firme farmers (a) to name all landraces that they cultivated in each type of soil and then (b) to rank the landraces mentioned according to their performance in that specific soil. Based on Sutrop's “Cognitive Salience Index” pri) of each landrace in each type of soil, using the formula:pri is the Performance Ranking index, F is the frequency of citations of the landrace, N is the number of farmers interviewed who cultivate in this specific type of soil, and mP is the mean position of the landrace in the rankings.During participant observation it emerged that farmers claimed that certain landraces performed better in particular soils separated seedlings, that is took cuttings from seedlings and planted them apart to see how they did; b) randomly incorporated seedlings, where they do plant cuttings of seedlings volunteers, but randomly mixed up with the other landraces; or c) removed them, cutting the volunteers out as weeds when they appeared in the field.Participant observation also revealed that some farmers purposefully separate cuttings from volunteer seedlings for later planting, others simply harvest them together with other landraces (resulting in their random incorporation into pre-existing landraces), and others purposefully exclude volunteers Thirty one farmers were selected to record the production of different bitter manioc landraces in mono-varietal patches within 43 fields on the four different soil types. They were selected on the basis of literacy, their expressed interest in participating in the study , and, crucially, the fact that they had mono-varietal patches within manioc fields during the study period. Bitter manioc fields are harvested bit by bit depending on labor availability and demand for manioc flour for subsistence consumption and sale. Amazonian farmers also do not tend to have accurate scales. They take a great interest in the amount of manioc flour produced, however, since it is equivalent to, as one woman put it, their “daily bread”  and additionally an important product for sale in markets. In order to measure production therefore we asked farmers to record how many sacks of manioc flour (each sack is 50 kg) they produced from each mono-varietal-landrace patch. Fields were visited and we did not record significant differences in spacing, so we consider them to be all planted at similar density (around 1 meter between plants – c. 5000 plants per 0.5 ha). The size of mono-varietal patches varied (mean 0.286 ha±0.123 SD), so we corrected each one up to 0.5 ha in order to make the data commensurate and comparable using ANOVA .Instituto Nacional de Pesquisas da Amazônia's Committee for Research Ethics (protocol 235/09) and our collecting was registered in the System for Authorization and Information on Biodiversity, coordinated by the Chico Mendes Institute for Biodiversity, of the Ministry of the Environment (number of register: 10020-5). No proprietary traditional knowledge was accessed, allowing us to meet Resolution 21 requirements for basic research that does not require authorization from Brazil's Council for Genetic Patrimony (CGEN in the Brazilian acronym), which was consulted before field work.The collection of plant material for genetic analyses was carried out in 2009. Authorization for interviewing farmers was obtained from et al.et al.To investigate how the genetic diversity of bitter manioc was organized in different environments of cultivation we collected leaf samples of each landrace present in each of a total of 48 swiddens in all the localities except Vista Alegre: 17 in ADE soils, 14 in floodplain soils and 17 in Oxisols/Utilsols. A total of 184 individuals were sampled, representing 43 different bitter manioc landraces. The genetic variation of landraces was accessed using ten microsatellite loci Pirarucu Branco, Tartaruga, Arroz, Jabuti and Pirarucu Amarelo) had 20 or 30 individuals sampled (OH) and expected (EH) heterozygotes with GenAlEx v.6.4, while the number of multi-locus genotypes (MLGs) was analysed with GenClone v.2.0 OH varies from 0 to 1, and corresponds to the probability that a given microsatellite locus has two different numbers of repetitions in a given individual. EH also varies from 0 to 1, and corresponds to the proportion of heterozygote individuals that were expected under the Hardy-Weinberg Equilibrium based on the number of different microsatellite forms found for a given landrace. The MLGs describe the number of different microsatellite combinations present in a given group of individuals . The detailed sampling strategy, material and methods and other genetic results are described elsewhere To investigate the extent of genetic variation within landraces and the genetic identity of landraces with the same name but grown in different soil types, some of the most commonly cultivated bitter manioc landraces in the region Click here for additional data file.Dataset S2Intra-varietal genotypes and soil differentiation genotypes.(XLSX)Click here for additional data file.Text S1Manioc cultivation at the community level.(DOCX)Click here for additional data file.