Children with attention deficit hyperactivity disorder (ADHD) experience many peer interaction problems and are at risk of peer rejection and victimisation. Although many studies have investigated problematic peer functioning in children with ADHD, this research has predominantly focused on boys and studies investigating girls are scant. Those studies that did examine girls, often used a male comparison sample, disregarding the inherent gender differences between girls and boys. Previous studies have highlighted this limitation and recommended the need for comparisons between ADHD females and typical females, in order to elucidate the picture of female ADHD with regards to problematic peer functioning. The aim of this literature review was to gain insight into peer functioning difficulties in school-aged girls with ADHD.PsychINFO, PubMed, and Web of Knowledge were searched for relevant literature comparing school-aged girls with ADHD to typically developing girls (TDs) in relation to peer functioning. The peer relationship domains were grouped into ‘friendship’, ‘peer status’, ‘social skills/competence’, and ‘peer victimisation and bullying’. In total, thirteen studies were included in the review.All of the thirteen studies included reported that girls with ADHD, compared to TD girls, demonstrated increased difficulties in the domains of friendship, peer interaction, social skills and functioning, peer victimization and externalising behaviour. Studies consistently showed small to medium effects for lower rates of friendship participation and stability in girls with ADHD relative to TD girls. Higher levels of peer rejection with small to large effect sizes were reported in all studies, which were predicted by girls’ conduct problems. Peer rejection in turn predicted poor social adjustment and a host of problem behaviours. Very high levels of peer victimisation were present in girls with ADHD with large effect sizes. Further, very high levels of social impairment and social skills deficits, with large effect sizes, were found across all studies. Levels of pro-social behaviour varied across studies, but were mostly lower in girls with ADHD, with small to large effect sizes. Overall, social disability was significantly higher among girls with ADHD than among TD girls.Congruous evidence was found for peer functioning difficulties in the peer relationship domains of friendship, peer status, social skills/competence, and peer victimisation and bullying in girls with ADHD. Attention deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder which often persists into adulthood and involves a persistent pattern of inattention and/or hyperactivity-impulsivity that interferes with functioning or development . ADHD afIn general, due to the unique presentation of ADHD in girls, they meet fewer ADHD diagnostic criteria as per DSM-5 , as suchNumerous studies have confirmed that peer functioning is often quite problematic for children with ADHD –36. It iThere are several reasons why problematic peer functioning has a major impact on girls with ADHD. First, as girls in general usually have tighter and more intimate social networks –53, and Due to these gender-specific problems, this review examines problematic peer functioning of girls with ADHD as compared to TD girls rather than to boys with ADHD. After all, the inherent gender differences between girls and boys without ADHD can be considered as different baselines from which to draw comparisons. Girls have different social (interaction) styles than boys and a comparison between girls and boys with ADHD will not give us the female specific information we are looking for. However, in the history of ADHD research, females with ADHD have rarely been compared to females without ADHD. Ohan and Johnston  stated tThe present literature review will (1) identify the domains in which school-aged girls with ADHD experience problematic peer functioning, (2) describe to what extent these girls differ from TD girls on the identified aspects of peer interaction problems, and (3) identify potential risk factors and protective factors for peer functioning, and describe their influence.This systematic literature review was performed conforming to the guidelines of Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA)  as well as protective factors (those that reduce the likelihood of such impairment) were identified in the literature and discussed, as was the impact of psychiatric comorbidities on peer functioning. An overview of the thirteen studies included in this review is presented in Friendship is a close relationship between two children that is mutual and reciprocal .no friends. This did not differ between girls with inattentive-type ADHD (Cohen’s d = 0.44) and those with combined-type ADHD (Cohen’s d = 0.44). Thirty-two percent of girls with ADHD had no reciprocal friends at the end of camp, relative to 17% of TD girls. Further, 29% of girls with ADHD had multiple friends at the end of camp, as compared to 52% of TD girls. The authors concluded that girls with ADHD struggle with making new friends, and, if they do make a friend, they appear less likely to make additional friends than TD girls. Friendship stability was investigated by using peer nominations at various points during the summer camp. No diagnostic group differences were found in friendship stability across week 1 to week 5. However, girls with ADHD Combined type (ADHD-C) were participating in fewer stable friendships than TD girls from week 1 to week 3 (Cohen’s d = 0.57); 51% of ADHD-C girls had no stable friendships from the beginning to the middle of camp, relative to 24% of TD girls. The mean number of stable friendships for girls with ADHD Inattentive type (ADHD-I) was in between the ADHD-C and TD means and did not differ significantly from either one. ADHD-I girls were participating in fewer stable friendships than the TD girls from week 3 to week 5 (Cohen’s d = 0.68); none of the ADHD-I girls were able to maintain multiple friendships, compared to 29% of TD girls. The mean for the ADHD-C girls fell in between and did not differ significantly from either of the other groups. The authors concluded that ADHD-C girls demonstrate greater initial difficulty maintaining stable friendships whereas ADHD-I girls show more difficulty maintaining multiple friendships over time. Friendship quality was examined by means of self-reports; which showed that the friendships of both ADHD-I and ADHD-C girls contained as much positive relationship features as TD girls, but higher levels of negative relationship features. This included higher levels of conflict, relational aggression within the friendship, and relational aggression to others. These negative relationship features were specific for the ADHD-C girls, with the exception of relational aggression within the friendship, where both ADHD-I and ADHD-C girls had higher levels than TD girls.Two studies investigated friendship in girls with ADHD during a 5-week summer camp for girls, using peer nominations following standard sociometric procedures. Blachman and Hinshaw  examinedd = 0.31). It was demonstrated that friendship moderated the association between behavioural risk  and peer victimisation for the sample as a whole; the presence of at least one friend reduced the risk of victimisation. In addition, girls with ADHD were shown to be similarly protected by the presence of a friendship than were TD girls. Having only friends with a diagnosis of ADHD did not reduce protection relative to having at least one TD friend in both the ADHD and the control group.Cardoos and Hinshaw , using tTo summarise; girls with ADHD were found to have lower rates of friendship participation and stability, which was most pronounced for girls with ADHD-C. Girls with ADHD who had friendships were better liked by their peers than those who did not, independent of whether these friends had a diagnosis of ADHD or not. Friendship quality was lower for girls with ADHD, which was explained by increased levels of negative relationship features within the friendships of these girls, Such negative relationship features which were more pronounced in the girls with ADHD-C compared to ADHD-I. For positive relationship features no difference was found between girls with ADHD and TD girls.d = 0.10). Notably, girls with ADHD and TD girls did not differ on receipt of negative peer nominations. Peer rejection was related to higher levels of problem behaviour, such as defiance, rule-breaking behaviour and aggression. This study also investigated social acceptance through teacher-ratings and peer nominations. Teachers reported the proportion of classroom peers that like and accept the child and the proportion that dislike and reject the child. Girls with ADHD were rated as like/accept less frequent than TD girls (Cohen’s d = 1.90), and as dislike/reject more frequent than TD girls (Cohen’s d = 1.09). Interestingly, girls with ADHD did not receive less positive nominations than TD girls, and there was a strong negative relationship between conduct problems and positive nominations for both girls with ADHD and TD girls. Finally, this study demonstrated increased levels of peer rejection in their sample of girls with ADHD, which were predicted by externalising behaviours; specifically rule breaking behaviour, observed disobedience, and conflict.Peer status is the extent to which someone is liked or disliked by their peers ,67. Seved = ranging from 0.25 to 0.69) and teacher-reported (Cohen’s d ranging from 0.10 to 0.98) popularity ratings. Further, the girls with ADHD were rated as having fewer positive peers (Cohen’s d = ranging from 0.13 to 0.89), and more negative peers (Cohen’s d = ranging from 0.18 to 0.56), than their comparison counterparts. All results in this study were most pronounced in girls with the inattentive type.Another non-sociometric study , examinePeer rejection was associated with greater emotional and behavioural problems, and with lower levels of protective variables, in all studies directly examining this variable. More specifically, in the study by Mikami and Hinshaw  peer rejNo relationship between ADHD in girls and peer regard was found in one sociometric study . This stIn summary; girls with ADHD were more likely to be peer rejected and were less popular than TD girls. However, one study found that although girls with ADHD received fewer positive peer nominations, they received similar negative peer nominations to TD girls. A strong positive relationship was found between conduct problems and teacher-reported peer rejection. Both ADHD and peer rejection predicted poor adjustment. Further, peer rejection was associated with higher levels of problem behaviour, and lower levels of protective variables. When measuring change over time, one study demonstrated that peer rejection and ADHD diagnosis predicted declining adolescent academic achievement.Social skills/competence refers to possessing the social, emotional, and intellectual skills and behaviours needed to interact positively with others . In totad = 1.53 for parent-report and 1.19 for self-report); such as conflict with peers, few social supports and dislike by peers. Further, their social problems were more often clinically significant relative to TD girls, by both parent- and self-report. Similarly, Cardoos & Hinshaw [d = -1.37) and that this put them at increased risk of being victimized by their peers. This association existed with both overt and relational victimisation.Sciberras, Ohan and Anderson , in thei Hinshaw , in theid = ranging from -0.22 to -5.34). On the laboratory task, girls with ADHD sent less frequent pro-social messages, but the content of the messages they did sent was similar in skills level to those of TD girls. Grskovic & Zentall [Two studies investigated pro-social behaviour, defined as positive social involvement, in girls with ADHD and evidenced contradictory results. Ohan & Johnston  studied  Zentall  investigIn synopsis; increased levels of social impairment, lower levels of social competence, and lower levels of general social functioning were demonstrated in girls with ADHD compared to TD girls. Social disability rates were significantly higher in the ADHD group than in the comparison group. Girls with ADHD also reported more social skills deficits, and these deficits were associated with lower levels of self-esteem. Girls with ADHD not only demonstrated increased levels of general social problems, but also showed more clinically significant social problems. Inconsistent evidence was found for an association between ADHD and pro-social behaviour in girls.no friends, the association between internalising behaviour and victimisation was stronger than for children with one or more friends. In a study on pre-adolescent adjustment in 515 girls with and without ADHD, Elkins and colleagues [d ranging from 2.54 to 5.20). This pattern was most pronounced in inattentive girls (Cohen’s d = 5.20). Further, one study [overt peer victimisation were significantly higher in the ADHD sample compared to the TD sample, by parent- (Cohen’s d = 0.74) and self- (Cohen’s d = 1.07) report. Levels of relational victimisation were also higher in girls with ADHD, by parent- and self-report, but this result was only significant for parent-report (Cohen’s d = 1.06). Further, this study did not demonstrate higher levels of overt and relational bullying in girls with ADHD, by either self- or parent-report.Peer victimisation refers to being a target of intentional, repeated aggressive behaviour by peers , whereaslleagues  investigne study  distinguOverall, in respect of peer victimisation; the studies included in this review demonstrated increased levels of peer victimisation in girls with ADHD. Notably, while overt victimisation was experienced significantly more by both parent- and self-report; relational victimization was only significantly higher in girls with ADHD by parent-report. Although this study did not give an explanation for such a finding, it is plausible that, by the very nature of ADHD, girls may not be aware of relational victimisation to the extent that typically developing girls would be, and that such victimisation may therefore be under-reported by the girls themselves.All included studies were examined for identified risk and protective factors for the development of problematic peer interaction in girls with ADHD.The main risk factor for problematic peer functioning in girls with ADHD identified was the presence of externalising behaviour see . It was Another identified risk factor was the presence of internalising behaviour in girls with ADHD, which was investigated in two studies. Cardoos and Hinshaw , in theiHigher friendship status was identified as protective factor in one study , which dA summary of identified risk- and protective factors is presented in Seven studies investigated the impact of comorbidity on peer functioning in their sample; six of these studies demonstrated differences between the comorbid and non-comorbid ADHD group. A summary of these results is presented in symptoms in girls with ADHD; two studies found that such symptoms were associated with increased social impairment, including bullying behaviour and victimization [The majority of studies that included girls with both ADHD and ODD/CD, showed impaired social and peer functioning relative to girls with ADHD only. Two studies demonstrated that comorbid ODD and CD diagnosis in girls with ADHD was associated with increased impairment in social functioning relative to girls with ADHD only ,74 and tmization ,76, but mization . In synoFew studies systematically investigated the impact of other comorbidities. The impact of comorbid anxiety in girls with ADHD was investigated in two studies, however findings were inconsistent. One study compared children with and without ADHD but also included diagnoses of psychopathology, and found that anxiety disorder was associated with impairment on three social dysfunction items . One stuThe aim of this systematic literature review was to determine in what way girls with ADHD are affected by peer interaction difficulties and to identify risk factors as well as protective factors in this relationship. In total thirteen studies were reviewed that examined peer interaction of female children (10 studies), adolescents (1 study), and both  with ADHD in comparison to TD girls. The studies included in this review incorporated multiple measures of peer functioning, comorbidity, externalising behaviour and protective factors. As these peer functioning dysfunctions were objectified by means of various measurement techniques and informants, namely behavioural observations, peer nominations, and parent-, teacher- and self-reports; confidence in conclusions is considerable.Congruous evidence for increased peer interaction problems and social dysfunction in girls with ADHD was found. All of the thirteen included studies reported that girls with ADHD, compared to TD girls, demonstrated increased difficulties in the domains of friendship, peer interaction, social skills and functioning, peer victimization and externalising behaviour. Studies consistently showed small to medium effect sizes for lower rates of friendship participation and stability in girls with ADHD relative to TD girls. Higher levels of peer rejection with small to large effect size were reported in all studies, which were predicted by girls’ conduct problems. Peer rejection in turn predicted poor social adjustment and a host of problem behaviours ,64,68–71This negative spiral of problematic peer functioning and the development of social skills has been reported by Mikami and Hinshaw , who sugmore of this behaviour than TD girls. Overall, these externalising and gender-non-normative behaviours often seen in girls with ADHD put them at risk of impairment in many aspects of social functioning.It has been suggested that social dysfunction in girls with ADHD may be caused by gender-atypical social behaviours. Ohan and Johnston  proposedThe problematic social and peer functioning experienced by girls with ADHD may also result from social cognition deficits, such as difficulty perceiving and being attuned to emotions in others, and reasoning about others’ mental state . InattenThis review has a number of strengths in exploring peer functioning difficulties in school-aged girls with ADHD. It is unlikely that the outcomes of this review are misrepresented by demographical differences between girls with ADHD and TDs within the studies concerning age, gender, and cognitive ability, because a vast majority of studies controlled for these factors by means of group matching or statistical correction. Further, limited sample size is unlikely to be an issue in this review, with 8 of the 13 studies including an ADHD sample that was bigger than n = 90. Three studies included an ADHD sample size that was smaller than n = 30, which would in general be considered a small sample size. Total sample sizes ranged from 41 to 515 and ADHD sample sizes ranging from 20 to 140.Despite these strengths, this review has limitations. The findings of this review hold primarily for children, as only one study conducted their investigation in an adolescent sample of girls, and two studies used a longitudinal design. In addition, although according to the Centers for Disease Control and Prevention  the percAnother limitation of the reviewed studies is that they may suffer from selection bias. Out of the thirteen studies included in this review, four studies use the same sample of girls. In addition, seven of these studies have been prepared by the Stephen Hinshaw workgroup. Selection bias can therefore not be ruled out and it is advisable that independent research groups replicate these findings. Further, the results of boys with ADHD were not included as the focus on this review was on the differences in peer functioning between girls with ADHD and their typically developing counterparts. However, research on gender differences in peer functioning among children with ADHD is scant and shows contradictory results. Some studies found that girls with ADHD were more likely to be reported by teachers as being peer rejected than boys ,87, wherThis systematic literature review found congruous evidence for increased peer interaction problems and social dysfunction in girls with ADHD. It highlights the impact of ADHD and related (gender)atypical behaviours across the peer functioning domains friendship, peer status, social skills/competence, and peer victimisation and bullying in girls. Gender-non-normative and externalising behaviours can limit these girls’ opportunities for social learning, leading to delayed development of pro-social skills and a consequent decrease in the quality of their peer interactions. This negative spiral of atypical behaviour and reduced socialization experience exacerbates problematic peer functioning and put girls with ADHD at risk of social maladjustment and psychopathology.These findings highlight the need for further research as well as careful clinical examination of the different aspects of social dysfunction in girls with ADHD and relevant interventions. It is proposed that effective interventions should be long-term and directly address gender specific peer interaction issues such as negative behaviours and (gender-specific) pro-social skills.S1 File(DOCX)Click here for additional data file.S1 Table(DOCX)Click here for additional data file.S2 Table(DOCX)Click here for additional data file.


Capitalizing upon the genomic characteristics of long-term random mating populations, sampling from pre-selected landraces is a promising approach for broadening the genetic base of elite germplasm for quantitative traits.Genome-enabled strategies for harnessing untapped allelic variation of landraces are currently evolving. The success of such approaches depends on the choice of source material. Thus, the analysis of different strategies for sampling allelic variation from landraces and their impact on population diversity and linkage disequilibrium (LD) is required to ensure the efficient utilization of diversity. We investigated the impact of different sampling strategies on diversity parameters and LD based on high-density genotypic data of 35 European maize landraces each represented by more than 20 individuals. On average, five landraces already captured ~95% of the molecular diversity of the entire dataset. Within landraces, absence of pronounced population structure, consistency of linkage phases and moderate to low LD levels were found. When combining data of up to 10 landraces, LD decay distances decreased to a few kilobases. Genotyping 24 individuals per landrace with 5k SNPs was sufficient for obtaining representative estimates of diversity and LD levels to allow an informed pre-selection of landraces. Integrating results from European with Central and South American landraces revealed that European landraces represent a unique and diverse spectrum of allelic variation. Sampling strategies for harnessing allelic variation from landraces depend on the study objectives. If the focus lies on the improvement of elite germplasm for quantitative traits, we recommend sampling from pre-selected landraces, as it yields a wide range of diversity, allows optimal marker imputation, control for population structure and avoids the confounding effects of strong adaptive alleles.The online version of this article (doi:10.1007/s00122-017-2959-4) contains supplementary material, which is available to authorized users. Zea mays L. ssp. mays) landraces are a rich source of untapped allelic variation, but efficient strategies for exploring their genetic diversity are lacking. The successful use of landraces for improving elite germplasm has been hampered by insufficient genetic and phenotypic information and their heterogeneous and heterozygous nature  to assess the genetic diversity of European landraces in a broader context.In this study, we analyzed genetic diversity, population structure, linkage disequilibrium (LD) and persistence of linkage phase within and across 35 European maize landraces with more than 20 individuals per landrace genotyped at high density. We investigated the effect of varying the number of sampled landraces and individuals per landrace on these parameters and give practical recommendations for assembling datasets for genome-enabled studies. We extended our analyses to Central and South American landraces of the Seeds of Discovery (SeeD) project (nLR) for each landrace are listed in Table S1. After DNA extraction following the protocol of Saghai-Maroof et al.  and for analyses across landraces individuals were randomly sampled under the side condition that each individual originated from a different landrace. Analyses were done using R version 3.0.1  SFS is then given by the vector f = . Following Nielsen and Slatkin (The term site frequency spectrum (SFS) refers to the distribution of allele frequencies for a given set of SNPs. Let  Slatkin , the expf* which describes the distribution of minor allele frequencies and is obtained by fi* = fi + fg−i for i < g/2 and fi* = fi for i = g/2. For a given dataset, g gametes with non-missing genotype calls were randomly sampled per SNP, where g corresponds to 2n × c with n referring to the respective number of individuals and c to the minimum call rate . For the estimation of the folded SFS, the number of minor alleles per SNP was averaged over 1000 random samples.Here, we calculated a folded SFS PP), nucleotide diversity (π) per marker , were randomly assigned to groups of l landraces, with the number of groups being the smallest integer ≥35/l. If 35 was not a multiple of l , one group comprised only l − 1 landraces. For each l, we conducted 10,000 random repeats. Following Excoffier et al.  approach was applied as implemented in ADMIXTURE. In dataset EU-Array we performed one run for each K varying from 1 to 25 and 20 runs with different seed settings for each K varying from 26 to 50. Additionally, for K = 35, 20 runs were conducted in a supervised mode, in which 35 genetic groups were pre-defined by choosing one individual per landrace as representative of the respective genetic group. In dataset SeeD-GBS, we performed 20 runs with different seed settings for each K varying from 1 to 25 and one run for each K varying from 26 to 50. For K = 35 (EU-Array) and K = 16 (SeeD-GBS) population structure according to the model with the lowest CV error of the respective 20 runs was visualized using a customized R-script.To analyze the genetic relationship between individuals, an unrooted neighbor joining tree  compared to within landraces (l = 1) was assessed using the two-sided Wilcoxon rank sum test . In addition to calculations including all individuals within the respective landrace, the number of individuals was varied from 5 to 45 in steps of 5. The effect of sample composition on LD estimates was assessed based on dataset EU-OL. LD calculations were performed for sampling schemes varying in the number of landraces l and the number of gametes g per landrace. In steps of 1, l varied from 1 to 35 and g from 1 to 44, as 44 was the minimum number of gametes per landrace in EU-OL. For each g × l combination, LD decay distances were averaged over 10 random samples. Calculations were performed for sampling schemes with g × l ≥ 12. To evaluate the effects of marker distribution on LD estimation, LD calculations for varying g and l were performed analogously for dataset EU-Array, with g and l varying in steps of 5.The effect of sample size on LD estimates was evaluated by calculating LD decay distances within the five landraces of dataset EU-Array with r values of the respective landraces and the proportion of marker pairs with equal phase (PEP), i.e. with equal sign of r  compared to the second half.To assess the persistence of linkage phase between landraces of dataset EU-Array, marker pairs were binned according to their physical distance in steps of 10 kb. For each bin and each pair of landraces, we calculated the correlation between the H, Fis, MRD and LD, missing genotype calls were imputed and the haplotype phase inferred using BEAGLE  and the CIMMYT Seeds of Discovery dataverse repository , though the three landraces with the highest PP and π values originated from Austria . For the five landraces with nLR ≥ 46 (Table S1), estimates of diversity parameters for 24 randomly sampled individuals were comparable to levels observed including all individuals within these landraces (Table S6). Values of Fis were low and not significant for most landraces, ranging from −0.064 to 0.118 with a mean of 0.006 (Table S4). Five landraces showed a small but significant excess of homozygotes at the 0.05 significance level suggesting deviation from Hardy–Weinberg equilibrium due to inbreeding and/or population structure. AMOVA revealed that 73.1 and 26.9% of the total molecular variance of the 35 landraces originated from within and across landrace variation, respectively. The across landrace variance component was significant with p < 0.001. On average, ~95% of the molecular variation of the entire dataset (EU-Array) was already captured by groups of five landraces . Different levels of relatedness between landraces were indicated by the formation of geographical clusters, e.g. for landraces from the Alsace region , from Galicia  and from the French Pyrenees . Plotting the first and second principal coordinates (PCo) of the PCoA, a group of north-eastern European landraces was located in the first and fourth quadrant and a group of south-western European landraces in the second quadrant . The third quadrant contained landraces from both regions. With the exception of ND, these landraces differed from the remaining landraces in their kernel morphology. While most landraces in dataset EU-Array showed typical Flint-like kernels with a thick, hard and vitreous outer layer, these landraces  displayed kernels with a small indentation, characteristic for Dent maize. Analogously, the NJT  showed groups of Dent-like north-eastern European  and Dent-like Spanish landraces , respectively.K in the dataset could not be resolved unambiguously for K ranging from 1 to 50. CV errors decreased until K = 35, showed only minor differences for 35 ≤ K ≤ 40 and reached a plateau for K > 40 . Therefore, given the 35 landraces in the panel, we chose one individual per landrace to represent the genetic composition of the respective landrace. A distinct separation of the 35 landraces was detected, whereas within landraces only limited evidence of population structure was observed . Mean r2 estimates calculated for 1000 random samples of 24 individuals across landraces were on average 0.096 and showed substantially less variation compared to within-landrace estimates, ranging from 0.091 to 0.102 . However, values of both parameters decreased rapidly with increasing physical distance between markers and reached moderate to low levels for marker pairs within distances of 990 to 1000 kb . The persistence of linkage phase between pairs of landraces was associated with proximity of geographical origin and kernel type. The correlation of r values for marker pairs within 1 Mb distance was lowest for the comparison of the northern European Dent-like landrace PL and the southern European Flint-like landrace ND (0.298) and highest for a pair of two Flint-like German landraces . PEP for marker pairs within 1 Mb distance was lowest for the comparison of the southern European Dent-like landrace TR and the northern European Flint-like landrace CO (0.564) and highest for a pair of two Dent-like Austrian landraces . As expected, when comparing samples within each of the five landraces with nLR ≥ 46 (Table S1), the two parameters were consistently high, for marker pairs within distances smaller than 10 kb  as well as for marker pairs within distances of 990 to 1000 kb  based on 1000 random samples of 35 individuals across landraces. All five parameters differed significantly between datasets (p < 0.001), as revealed by two-sided t tests with Bonferroni correction. The levels of PP and π were highest for EU-OL, slightly lower for SeeD-OL and lowest for SeeD-GBS. SeeD-GBS showed the highest level of H and only slightly lower values were observed for SeeD-OL, whereas H was lowest for EU-OL. Mean r2 for marker pairs within 1 Mb distance and r2 decay distances were highest for EU-OL, substantially lower for SeeD-OL and lowest for SeeD-GBS.For each dataset, we estimated K varying from 1 to 16 and reached a plateau for K > 16 . Thus, we defined 16 genetic groups within SeeD-GBS. The resulting groups reflected the geographical origin of the respective landraces . Five groups originated from the Mexican and Central American lowlands, four groups comprised landraces from the Mexican highlands, four groups referred to landraces from South America and three groups originated from the Caribbean islands and north-eastern South America. Individuals showed high levels of admixture, especially between geographically adjacent groups.We used ADMIXTURE to identify major genetic groups within the American landrace panel (SeeD-GBS). CV errors decreased for the number of genetic groups In the joint PCoA of SeeD-OL and one representative of each of the 35 European landraces sampled from EU-OL , the first two PCos mainly separated South American from Mexican highland landraces with tropical Caribbean and Central American lowland landraces at the center. A group of north-eastern European Flint landraces was clearly separated from the American landraces. Part of the temperate European landraces, mainly from the south-west, grouped together with part of south-eastern South American landraces, but was clearly separated from the remaining groups. The genetic distance of European landraces to tropical Caribbean and Central American lowland landraces increased with increasing geographical distance to Mediterranean regions and was larger for Flint-like than for Dent-like landraces.p < 0.001; Fig. S10). Consistently larger MRDs were observed for SeeD-OL compared to SeeD-GBS. For the first three principle coordinates, the correlation-like statistic of Procrustes analyses was 0.994 for the comparison between EU-OL and EU-Array, and 0.991 between SeeD-OL and SeeD-GBS, respectively (p < 0.001).To evaluate the representation of population structure by the reduced marker sets EU-OL and SeeD-OL, we compared MRDs and PCoA between EU-OL and EU-Array and between SeeD-OL and SeeD-GBS, respectively. MRDs between individuals obtained by the respective reduced and full marker sets were highly correlated , a strong increase in mean and variance of LD decay distance estimates was observed with decreasing sample size . We also calculated LD decay distances for sampling schemes varying in the number of landraces l and the number of gametes g per landrace, based on dataset EU-OL. As expected, estimates of LD decay distance increased with decreasing total number of gametes  than across landraces (l > 1). For example, an LD decay distance of 174.3 kb was observed for 35 gametes sampled from one landrace in contrast to 8.3 kb when sampling 35 landraces with one gamete each. In general, LD decay distances decreased for increasing l, with the largest decrease observed for l from 1 to 10, and only marginal changes for l larger than 10. Analogously, LD calculations for varying g and l were performed for dataset EU-Array. A decrease in LD estimates with increasing g and l was also observed for EU-Array, but with substantially higher overall levels of LD compared to EU-OL . The different levels of genome-wide LD estimates between EU-OL and EU-Array can be explained by differences in the distribution of markers, with EU-OL showing a higher marker density in telomeric regions compared to EU-Array . However, LD estimates of landraces relative to each other were comparable between EU-OL and EU-Array (Table S6).Based on dataset EU-Array, we analyzed the effect of sample size on LD estimates by calculating LD decay distances for random samples of individuals within each of the five landraces GB, KL, LL, PE and VI with l = 1, 2, 3, 4, 6, 8, 12, 24 landraces. Overall, the proportion of interchromosomal marker pairs with r2 > 0.2 was low (Table S8), but the Wilcoxon rank sum test revealed significantly higher proportions of marker pairs with r2 > 0.2 across landraces (l > 1) than within landraces (l = 1).In admixed populations, LD can appear between unlinked markers due to differences in allele frequencies of subpopulations. To assess the extent of admixture-induced LD, we calculated interchromosomal LD for 24 individuals sampled from When building GWAS discovery panels or training sets for genomic prediction from landraces, large data sets of several hundreds or even thousands of individuals are required to obtain sufficient power of QTL detection and high accuracy of prediction. Different sampling strategies can be devised depending on the aim of the study. When aiming at elucidating mechanisms of plant adaptation or discovering novel alleles for disease resistance or quality traits, maximizing the allelic diversity of the discovery panel is crucial. Thus, individuals might be sampled from many landraces covering a wide range of diversity with each landrace being represented by one or few individuals. An alternative strategy is to sample many individuals from each of a few pre-selected landraces, which might be especially promising for broadening the genetic diversity of elite material for quantitative traits.Fis values, a consistent landrace-specific grouping of individuals in NJT and PCoA, and high ancestry proportions of individuals attributable to their respective landrace . Array-derived SNPs are restricted to the initial SNP discovery panel and affected by subsequent filtering steps, leading to an enrichment of intermediate allele frequencies compared to GBS-derived SNPs. As the array was optimized for temperate maize, PP, π and r2 estimates were likely overestimated in European relative to American landraces. In both, the EU-Array and the SeeD-GBS datasets, SNPs were called using the B73 reference sequence and are, therefore, restricted to genomic regions present in B73. GBS-derived data depend on restriction enzyme cutting sites and hence are highly overrepresented in telomeric regions  consistent with previous observations  with respect to their geographical origin and kernel type was clearly reflected in the genomic analyses. The level of interchromosomal LD induced by admixture was overall low, but, as expected, varied significantly depending on the sampling strategy (Table S8). However, when constructing data sets by sampling individuals from pre-selected landraces, the clear differentiation between populations allows a priori definition of subpopulations in statistical analyses to avoid false-positive marker-trait associations or inflation of prediction accuracies. In addition, when sampling a sufficiently high number of individuals within landraces, specific marker effects can be estimated using appropriate statistical models as suggested by Lehermeier et al. .Even though only one or few individuals were sampled from individual landraces in the SeeD-GBS data set, population structure was prevalent with 16 genetic groups mainly representing the geographic origin of the landraces . With a high proportion of individuals exhibiting strong population admixture, accounting for population structure in the SeeD data set is challenging. Furthermore, the consistency of allelic effect estimates of samples of landraces covering a wide range of geographic regions with respect to a given target elite breeding pool warrants further research. It has been shown that strong correlations of geographic coordinates and specific adaptive traits persist in these data sets Supplementary material 2 (PDF 9158 kb)Supplementary material 3 (XLSX 43 kb)Below is the link to the electronic supplementary material.


Ensete ventricosum (Welw.) Cheesman) belongs to the order sctaminae, the family musaceae. The Musaceae family is subdivided into the genera Musa and Ensete. Enset is an important staple crop for about 20 million people in the country. Recent publications on enset ethnobotany are insignificant when compared to the diverse ethnolingustic communities in the country. Hence, this paper try to identify and document wealth of indigenous knowledge associated with the distribution, diversity, and management of enset in the country.Enset . All ethnic groups in the study area use five use categories in order of importance: It can be concluded that the existing farmers’ knowledge on naming, classification and diversity should be complemented with maintenance of the creative dynamics of traditional knowledge and transmission of the knowledge are crucial for constructing sustainable management. Ensete ventricosum (Welw.) Cheesman) belongs to the order sctaminae, the family musaceae. The Musaceae family is subdivided into the genera Musa and Ensete [The Ethiopian highlands are a center of genetic diversity for enset, tef, sorghum, barley and finger millet . Enset  leaf sheaths and grated corms. Bulla is obtained by squeezing out the liquid containing starch from scraped leaf sheathes and grated corm and allowing the resultant starch to concentrate into white powder. Amicho is boiled enset corm pieces, mainly obtained from young enset plants that are prepared and consumed in a similar manner to other root and tuber crops [The major food types obtained from enset are er crops .Studies indicate that numerous enset cultivars were identified in each region and the observed genetic diversity in cultivated enset in a particular area appears to be related to the extent of enset cultivation and the culture and distribution pattern of the different ethnic groups .A clear understanding of the diversity and distribution of enset is important for crop improvement programs and for managing genetic resources. To measure the status of crop diversity in the field the most common method is counting named varieties. There are two main landrace diversity indices, namely: cultivar richness, which represents the number of landraces in a community, and cultivar evenness, representing the relative abundance of the individuals among the various landraces present in the community , 9. For Indigenous technical knowledge is the tool by which local people interact with the environment in order to meet needs and goals ranging from survival goals to that of achievement and esteem . It is kThe southern and southwestern part of Ethiopia has an extraordinary biological and cultural diversity. Recent publication on enset ethnobotany including those by , 14 atteHence, the objectives of this study was to identify and document wealth of indigenous knowledge for folk naming, classification, distribution and abundance of enset landraces and understanding the corresponding knowledge related to utilization, management and conservation of enset landraces.The SNNPR is one of the regions in Ethiopia. It is located in south and southwestern part Ethiopia, 4.43°–8. 58° N latitude and 34.88°–3914° E bordering Kenya to the south and South Sudan to the west and southwest, the Ethiopian region of Gambela to the northwest, and the Ethiopian region of Oromia to the north and east  in the Southern Nations, Nationalities and Peoples’ Regional State (SNNPRS). The eight ethnic groups were selected for the following reasons:Two wereda were selected from each ethnic groups based on enset diversity Table . Then, t, zones, weredas and kebeles. All stages were selected purposefully from high (>2500 m.a.sl) and mid altitude (1500–2500 m.a.sl) [Multistage sampling technique was employed for selection of samples m.a.sl)  areas inDiverse data collection methods were employed in order to understand the many features for the acquirement of local knowledge of enset naming, classification, diversity and management in the center of diversity. The data collection was conducted mainly through: i) individual interviews and direct on-farm participatory monitoring and observation, ii) key informant and focus group discussions, and iii) secondary data and literature survey.Before interviews were performed, informal conversation was conducted with 20 inhabitants of the enset community with the objective of determining which type of information needed to be collected. Based on these conversations, semi-structured interviews were designed and data collected with the head of the household or the person responsible for maintenance of the enset plantation. Three hundred twenty farmers were interviewed and directly monitored on farms, over the selected weredas in order to assess the farmers’ ethnobotany knowledge on enset.The questionnaire covered different topics such as information about the study area, landholdings, crops commonly grown and specific information on the use and management of enset. The detailed information was focused on enset diversity, cultural practices, source of planting materials, and traditional use values of enset. The respondents were also asked about their perception on enset production constraints and their indigenous knowledge about the disease.In order to assess the general indigenous knowledge of farmers’ in each ethnic group: key informants up to five per KA, community leaders, local administrations, and MOA (Ministry of Agriculture), and other members in each ethnic site were interviewed.National Enset Research Project progress report was visited for secondary data and personal communication and discussion with elderly people and senior experts in line with ethnobotany tradition of enset. Literatures on enset culture were reviewed from published and unpublished sources and reports.Informal discussion with elderly farmers, and key informants were carried out to validate the information gathered from individual interviews. Lists of all landraces described throughout the study area were summarized after grouping known synonyms or names that refer to the same landraces in each wereda with the help of elderly farmers.Collected survey data were subjected to descriptive statistics  using SPSS Ver. 16. Landrace richness, diversity and dominance per farm were calculated using Microsoft excel 2010. Richness was calculated as the total number of landraces per farm and averaged this figure per ethnic group. Abundance was calculated as the total number of individual plants of each landraces per farm/household. Frequency was estimated as the number of individuals of a landraces with respect to the total number of landraces composing the enset farm. With these parameters we calculated the ecological importance index of each cultivar per farm.H' = − Σ pi ln pi, [th landrace. Then we calculated the dominance as a measure representativeness of each landrace through the Simpson index. Simpson’s Index of Diversity (1 – D) was computed for all the zones and all the landraces using the function: Simpson’s Index of Diversity (1-D) = 1-∑ (n/N)2.The Shannon and Weaver  and Simpi ln pi, . Where pi = the frequency of the ith landrace, frequency being the number of farms in which the landrace is found in the district, and N = the total number of farms surveyed in the zone.Equity, the proportion of the observed diversity with respect the maximum diversity expected was calculated through the Pielon index: J = H’/H’max, in which J is equity; H’ = diversity; H’max = maximum diversity, H’max was calculated as the ln(S) S being the number of landraces in a sample. Pearson’s correlation coefficient was used to compare diversity and distribution values at different ethnic groups.kocho yield and quality, bulla quality, amicho use), fiber  and medicinal/ritual categories. Food and medicinal categories refer to use by both humans and animals.We used a multiple use curve  concept Enset-based farming system is one of a major agricultural system in Ethiopia that serves as a backbone for at least one-fifth of country’s population. Enset has been selected as a typical multipurpose crop of which every part is thoroughly used for food, feed, medicinal, construction and ornamental purposes. Throughout the growth stage the corm, pseudostem and leaves are sued for various purposes. Enset is intimately associated with the daily lives of the farmers. Owing to these facts, farmers indicated that, ‘enset is everything for us’. ‘It is our food’ Fig. , ‘it is Ensete is the genus name, while different ethnic group use different vernacular terms as a local name for Ensete. In the study area, Ensete ventricosum is identified through various local names , fiber quality and medicinal value were the major criteria used by farmers. The interviewees referred first to the morphological characters (48 %)  Fig.  of any eWe recorded a total of 440 folk varieties (landraces) across the eight ethnic groups. From the total 128 (29 %) landraces shared the same name in at least two ethnics and the total number of landraces reduced to 312 Table . As farmBased on the total number of different landraces recorded (richness of the ethnic group) and the number of enset landraces per farm, Dawro farmers’ had the highest number of landraces (75) accounting for 24 % of the total number of recorded landraces across the study area. In contrast, the lowest richness was found in Gedeo farmers’ with 26 landraces accounting for 8.33 % of the total number of recorded landraces (Table r = 0.90 and 0.70). All these values indicate the high enset diversity in these eight ethnic groups.Diversity indices for the eight ethnic groups studied were computed from the numbers of landraces present on the 40 farms within the ethnic , fiber  and medicinal/ritual value as described in Table kocho yield and quality) were (≥35 house hold/ethnic) observed in all ethnic groups.All ethnic groups in the study area use a combination of different criteria to group enset landraces. We recorded three use categories, as defined by 25), in order of importance: Food Systematic propagation of the landracesSystemic propagation of the landraces is practices used by all farmers in the study area to adjust and to maintain the landrace diversity. Almost all farmers in the study area use corms of 3 to 4 years old enset plants with some portion of the pseudostem to produce enset seedlings Fig. .Fig. 6SyAlmost all respondents indicated that there are three to four growth stages or frequency of transplanting before harvesting Table . The inf(ii)Exchange of planting materialTraditional planting material exchange system is an important source of diversity for majority of farmers. Out of the 320 farmers interviewed 249 farmers use corms from their own farms Fig. . One fou(iii)Selective pressureFarmers continue to face many risks because of enset’s vulnerability to biotic and abiotic problems, and global climate change. Landraces which perform better under different biotic stress, and diverse agro-ecological conditions, and having multiple uses should be recommended to these subsistence farm households in order to sustain their livelihoods. Almost all informants stated that the population of enset has declined in recent times both in abundance and in distribution. The factors purportedly responsible for this decline were both agriculture and natural (disease and pest and drought) Table Table 13MXanthomonas wilt (EXW) had the greatest impact on enset production. Nearly 36 % of farmers reported the existence of EXW in their fields  systematic propagation of the landraces, (ii) exchange of planting material (iii) selective pressure.2 of land is covered by enset crop and about 6.9 million quintals of enset yields were produced in 2010/11 production season.Enset is well-established, sustainable, and environmentally resilient farming system that contributes to food security of farmers and, in particular it serves as food security crop in densely populated areas. Enset needs to be present in farmers’ pits throughout the year. Enset is the most important crop in the region. According to 2011 CSA  report 3All farmers are using the landraces developed by the community . These lex situ collection. This is also in agreement where folk taxonomy is used to highlight the amount of genetic diversity [Farmers’ rich knowledge that is accumulated on the crop over many years has played a significant role in naming, characterization and maintenance of the existing genetic diversity. Enset producing farmers have their own folk naming and classification system to distinguish one landrace from the other. Sometimes it is difficult to understand and reclassify, even while watching them to characterize. The classification of enset landraces has been accommodated by phenotypic differences, unique traits and specific uses of landraces. As pointed out by , 13, 14,iversity , 26, 27.iversity , 29. Ensiversity  depict iiversity  and riceCommonly, knowing folk names and classification may distinguish varieties that are actually genetically very closes. Farmer’s in one household generally knows which households certainly have named varieties and their particular agronomic and use value related characteristics. Knowing folk taxonomy also helps in developing planting material distribution, flow channels, and regional landrace map. Thus, even if landrace names and classification are a necessary basis, they are not sufficient to describe genetic diversity. Integrative indicators have been designed e.g., complementing the naming and folk classification with parameters of genetic diversity. Our data thus needs to be complemented by phenotypic and genotypic information which helps to avoid redundancies and optimizing the efficient conservation and sustainable use of the crop.Enset farming systems are rich in landraces diversity. In the study area we recorded a relatively high landraces (312) richness of enset. For instant, in previous studies, comparable results were reported by , who deskocho yield and quality have got a wider distribution within and between ethnic groups/zones. For example, the enset landraces ‘Shododenia’ and ‘Addo’ were encountered on respectively 37 and 34 (92.5 and 85 %) farms visited in Dawro and Sidama, but were not found in any other surveyed zones. Some landraces had a very high local abundance at one or two locations and were absent from the rest. For example Shodedenia was encountered on 100 % of the farms visited in Dawro. It was encountered on all the 40 (100 %) farms visited in Dawro. Likewise, [Genticha) playing a dominant role in Sidama zone. Our study revealed that the highest use values of the landraces were found in the region which also corresponds to where the landraces had the highest abundance in the farming system. This suggests a positive relationship between plant abundance and use. These findings corroborate the “apparency hypothesis” which describes dominant, large and more abundant plant species as having the highest use values.Enset is a multipurpose crop which is utilized for different use values. Based on their use value and folk classification large differences were evident between landrace abundance and distribution in the region. Some landraces, particularly those having merits of better ikewise,  reportedXanthomonas campestris pv. musacearum, is the most important biotic constraint to enset cultivation [kocho yield of these disease tolerant landraces is however below average [amicho use value. Female landraces are described by farmers as less vigorous, susceptible to disease, having a higher kocho quality and producing edible and tasty amicho [Astara’ and ‘Addo’ are known for their kocho yield and fiber quality. Similarly, in the Kembata area the landrace ‘Siskela’ is maintained by farmers for its high fiber yield and quality in addition to its high kocho yield. Studies by [Enset bacterial wilt, caused by tivation . In orde average , 27. Mor average  reported average , 30, 31.udies by , 25 reveudies by  or in riudies by .Knowledge of the local usage of enset resources is essential for the elaboration of conservation strategies. This is the first time that the use values according to various ethnic groups in the study area have been evaluated in detail for enset. Overall, we found less diverse ethnic variation in knowledge and use values of enset, as has been found for difference within the same ethnic group , 14. In in situ conservation. Farmers generally choose planting material from their existing mats. Farmers plant their enset landraces mixed on their fields, usually two or ten, but sometimes up to 20 landraces in one plot. It is traditional to use a corm and sucker as planting material and use of different transplanting stages in enset producing farmers. It was found that many households could propagate enset landraces in at least two ways and this flexibility of propagation might also reflect a relative preference for growing in a large area. A similar observation was also reported in other enset growing areas [in situ. Farmers observe and select the landraces based on their planting intentions for the coming year than the proportion to the quantity they have. This scenario has been maintained by the systematic propagation of 3–4 years old enset landraces. Other study [In the region, farmers’ manage local enset landraces within traditional production and processing systems oriented towards meeting household subsistence needs. Both women and men as producers, selectors, processors and marketers of enset are traditionally the custodians of ng areas , 30, 31.er study  revealeder study .The number of landraces grown at a given locality, their genetic similarity and the areas they occupy over time and space are influenced by planting material source, exchange and supply. Most planting material exchange is local, though a small proportion extends beyond the local group of villages reflecting relationships among neighbors and kin in most cases. All landraces used in the region are local farmer-named varieties. Among the surveyed farms, most farmers produce their own planting material. In addition farmers in the region have fixed systems to ensure the sustenance of planting material supply for each season. Farmers in cereal based farming system have well-established systems to ensure self-sustaining seed supply system and they often operate the exchange of planting material in the local market . In geneXanthomonas wilt (EXW), enset root mealy bug, leaf hopper, mole rat, Porcupine, wild pigs, corm rot, and drought. It is the EXW which has had the greatest impact on enset production. In Hadiya zone Lemu wereda 30 % of enset crop affected by EXW [in situ or on farm conservation.Similarly farmers in the region quite frequently practices grow their landraces in mixture to stabilize their crop production, especially under adverse growing condition. Farmers may retain their preferred landraces over many years, often claiming they received no external inputs of seed/planting material. Plant diseases can also reduce the level of biodiversity or limit the variety of plants grown in an area. It have been observed that, the genetic base has been vulnerable to a range of very damaging biotic and abiotic stresses such as Enset d by EXW . Therefod by EXW  indicateThe information collected in the region and presented here shows that a certain wealth and diversity of knowledge regarding traditional naming, uses of plants and diversity management as a part of the cultural heritage of the community. Farmers’ have been growing enset for many years. The farmers’ knowledge and enset have been coevolving together. This has resulted in the prevalence of rich indigenous knowledge of the farmers. Any attempt to improve the crop needs to take in to account the farmers knowledge and experience.Folk naming and classification are not consistent across all ethnic groups. The inconsistency is highly related with the ethnolinguistic variation in the region. Integrated folk-formal classification and characterization will be imperative for management and utilization of on farm genetic resources.kocho, bulla, amicho, fiber and medicine. Certain traditional practices  also lead farmers to maintain small quantities of uncommon landraces that may not produce well. This scenario points to the importance of use value based and other criteria similarity and differences for landrace diversity maintenance and management. Hence, formal enset improvement program needs to positioned in to multipurpose enset variety development scheme and include farmers and their knowledge in the research-extension continuum.Our study confirms that the landrace diversity and distribution makes it possible to gain a general picture of the uses made of such crop on a macro-scale. A principal conclusion from the present study is that the biggest uses of landraces, in terms of the number of citations in the literatures, are for Landrace diversity in the region is affected by a number of factors. EXW is the main factor limiting enset richness and diversity. Any attempt to improve enset has to give emphasis on enhancement of farmers’ varieties and a systematic operational approach to the management of EXW.It can be concluded that the existing farmers’ knowledge on naming, classification and diversity should be complemented with maintenance of the creative dynamics of traditional knowledge and transmission of the knowledge are crucial for constructing sustainable management.


The Kuwaitis were better when moving their arm leftward while the British showed the opposite bias. Bayesian analysis techniques showed that while children were worse than adults, they also showed asymmetries—with the asymmetry magnitude related to accuracy levels. Our findings support the idea that culture influences the sensorimotor system.The nativist hypothesis suggests universal features of human behaviour can be explained by biologically determined cognitive substrates. This nativist account has been challenged recently by evolutionary models showing that the cultural transmission of knowledge can produce behavioural universals. Sensorimotor invariance is a canonical example of a behavioural universal, raising the issue of whether culture can influence not only which skills people acquire but also the development of the sensorimotor system. We tested this hypothesis by exploring whether culture influences the developing sensorimotor system in children. We took kinematic measures of motor control asymmetries in adults and children from differing cultures where writing follows opposite directions. British and Kuwaiti adults ( For exawhich skills we acquire over the lifespan. But can culture influence the development of the sensorimotor system? There is general consensus that the human motor control architecture includes both adaptive forward models and inverse models. Forward models are used by the central nervous system to estimate the sensory consequences of motor actions while inverse models specify the motor commands appropriate for a desired behaviour .FiParticipants were instructed to sit in a comfortable position, remove any obstructive items of clothing, and trace the shape on screen from the starting point to the finishing point in one continuous action with their preferred hand. In each trial, the location of the starting point (signified by a green dot) and finish point (signified by a red dot) would differ. Depending on the locations of the starting point in each trial, the directional movement required would differ between tracing from left to right and tracing from right to left. Each trial commenced when participants placed the stylus on the starting point for 500 ms, after which the shape and the finishing point appeared on screen. The participants were then instructed to trace the shape as quickly and as accurately as possible. The trials were repeated with the location of the starting point and finishing point randomized for each participant, therefore requiring the participants to trace the shape four times for each direction.Kinematic data were collected and processed by specialized software ,16. Partiy from a normal distribution with a mean that depended on age group, nationality and tracing direction. The standard deviation depended only on age group.m = 1,…,M, are batches of coefficients. Each m-th batch of coefficients for the i-th data point. σ is a vector of coefficients, where elements σ1 and σ2 are the variance parameters for each age group. All priors were chosen to be vague on the scale of the data. Bayes rule was used to estimate the credible values of all the model parameters (θ) given the data. The posterior distribution is given byThe results were analysed using Bayesian Estimation techniques. First, a hierarchical linear model was specified as below. The model drew each error score θ, taking 1250 warm-up iterations followed by 1250 samples each. Convergence was visually assessed by examining the chains. All A representative sample was drawn from the posterior using the ‘No-U-Turn sampler’  implemenpository .3.M, the HDI is the narrowest possible interval of that mass [η. If η > 0.975 or η < 0.025 this indicates that the 95% HDI does not contain zero, which is indicated by an asterisk. The contrasts provide distributions over the credible differences between group means. We take a simple Bayesian heuristic approach to testing the ‘null’ hypothesis, where we consider the null unlikely if the contrast's 95% HDI does not contain zero [The posterior estimates of the condition means are shown in hat mass . The 95%hat mass . We alsoain zero . Howeverη = 0.0*). There was a difference between British and Kuwaiti children with Kuwaitis having lower tracing error . A small difference between British and Kuwaiti adults was plausible but the 95% HDI contained zero .Tracing error was much lower in the adults than the children  as did Kuwaiti adults . For British children, the difference in tracing error for preferred versus non-preferred direction was less clear . The 95% HDI spanned zero and was quite wide indicating uncertainty in the estimate. Kuwaiti children also showed lower tracing error in their culturally preferred tracing direction . The 95% HDI contained zero, but there was a 97.27% chance (1 − η) that the contrast was less than zero and the most credible values suggested a difference of reasonable magnitude. We also compared the difference between children and adult performance advantage for their culturally preferred direction . The 95% HDI spanned zero but was also quite wide, making it difficult to establish a null finding.British adults showed lower error when tracing in their culturally preferred direction compared with their non-preferred direction  effect describes the phenomenon whereby individuals represent numbers according to their normal cultural organization . Thus, sWith this in mind our findings may have implications for educational systems. Owing to increased multicultural environments across many countries, children can be exposed to one type of script at home (e.g. right to left), and another when they start formal schooling (e.g. left to right). It is possible that learning two different control dynamics will be advantageous (giving greater sensorimotor flexibility) but it may also cause negative interference. The probability of an advantageous outcome may reflect the richness of the different learning environments, which might mean that other factors, such as socioeconomic position, play a mediating role. These notions are speculative but our experimental findings suggest they are issues that warrant further investigation. In conclusion, our findings support the idea that culture influences the motor system in the same way that culture influences the core cognitive processes involved in the representation of abstract concepts. It follows that a complete understanding of human behaviour requires a consideration of motor control processes, cognitive representations, cultural transmission, and how these various factors interact.


ADHD. In a previous investigation of a large population cohort, impaired ‘emotional/social cognitive’ processing, assessed by questionnaire, was observed to mediate the link between COMT Val158Met and aggression in individuals with ADHD. We set out to replicate and extend this finding in a clinical sample, using task‐based and physiological assessments of emotional and cognitive processing. Our aim was to test the hypothesis that directly assessed emotional processing mediates the link between COMT Val158Met and aggression in young people with ADHD.There is a known strong genetic contribution to aggression in those with ADHD were recruited from UK community clinics (n = 194). Research diagnostic interviews (parent and child) were used to assess psychopathology and generate DSM‐IV Conduct Disorder symptom scores. Participants completed tasks assessing executive function (response inhibition and set shifting), empathy for fear, sadness and happiness, and fear conditioning [measured using skin conductance responses (SCR) to aversive stimuli].Males aged 10–17 years with COMT Val allele carriers showed poorer response inhibition  and set shifting abilities , reduced fear empathy  and reduced autonomic responsiveness (lower SCRs) to the conditioned aversive stimulus . COMT Val158Met did not predict impairments in recognising others' emotions or affective empathy for happiness or sadness. Mediation analysis revealed that impaired fear‐related mechanisms indirectly mediated the link between COMT Val158Met and aggression.ADHD. Our findings also reveal the potential of hypothesis‐driven approaches for identifying neuropsychological mechanisms that mediate genetic risk effects on behaviour and psychopathology.Our findings suggest fear mechanisms as possible targets for psychological interventions to disrupt links between genetic risk and aggressive outcomes in  Thus, it is a priority to identify novel psychological and biological targets for informing the future development of effective interventions. However, to achieve this goal, we need to identify causal mechanisms that underlie the development of aggression in patients with ADHD.Aggression is a well‐established adverse, potentially harmful outcome in individuals with ADHD . Our aim was to replicate and extend previous findings and test the hypothesis that emotional processes characterised at a behavioural and physiological level bridge the link between COMT and aggression in children with ADHD.In the present study, we set out to replicate and extend this finding and more precisely delineate the link in a patient sample. Rather than using questionnaires to measure emotional processing, we conducted lab‐based cognitive and physiological assessments of empathy and fear conditioning as well as executive functioning in a clinical sample of adolescent males with ADHD  structured interview using parents and adolescents as informants  had been generated on most previous participants using the GWAS Illumina 660K array .DNA was extracted from saliva (Oragene) or venous blood samples. Genotype data for the COMT Val158Met and performance on the Wisconsin Card Sorting Task  Heaton,  measuresThe GNG task (Go/No‐Go)  that was utilised in the Langley et al.  cohort aThree clips depicting the emotions of sadness, happiness and fear were edited from cinematic films   involves assessing electrical conductance that is affected by sympathetic nervous system activity. Electrodermal activity was recorded using a skin conductance amplifier  and sampled at 500 Hz from the distal phalanges of the index and middle fingers of the nondominant hand. The fear conditioning paradigm replicated the procedure described by Bechara and Damasio  and FairCOMT Val158Met genotype  and according to the presence/absence of categorically defined aggression (ADHD vs. ADHD+CD). For the fear conditioning paradigm, measures were mean SCRs to the CS+ (unreinforced blue slides) or CS− (red slides), or mean increase in SCRs during the CS+ or CS− corrected for baseline SCRs. Correlations were assessed for dimensional measures using Pearson's correlation coefficient. Analyses were carried out using SPSS 20 .Analysis of variance (ANOVAs) was used to examine differences in task performance by COMT Val158Met genotype and aggression in ADHD. Mediation analyses were undertaken according to the criteria proposed by MacKinnon, Lockwood, Hoffman, West, and Sheets  and dependent variable  are both significantly associated with the putative mediator . Significance of the indirect pathway was considered if the bias corrected 95% confidence interval did not cross zero .In accordance with previous papers, the Val allele had poorer response inhibition and set shifting abilities , reduced fear empathy (feeling someone else's fear) and more impaired fear conditioning (reduced SCR increase to the CS+). COMT Val158Met did not predict impairments in recognising others' emotions (cognitive empathy) or the vicarious experience of others' happiness or sadness; effects were restricted to fear empathy. The number of participants differed between individual tasks due to practical (task not fully completed) and experimental (data not useable) considerations, but there were no significant differences on clinical, demographic or genotypic measures between those who did and did not complete each task (see Table S3) or between those on medication versus not.Comparison of the genotype groups Table  showed sCOMT Val158Met did not directly predict aggression  versus 1.1 (SD 1.3); p = .83) or conduct disorder  versus 3.3 (SD 2.8); p = .73; 48.6 % with CD diagnosis in Val allele carriers, p = .73) in this sample in contrast to the original total larger genotyped ADHD sample from which the participants were drawn.Comparison between ADHD adolescents with and without a diagnosis of Conduct Disorder (CD) revealed no group differences in executive performance or cognitive empathy; similarly, the quantitative measure of aggression was not associated with measures of executive functioning or cognitive empathy  a direct pathway between predictor and outcome and (b) an indirect pathway via the ‘intermediate’ variables of (i) fear empathy and (ii) fear conditioning. Two separate analyses were conducted as performance on the task assessing affective empathy for fear and the physiological measure of fear conditioning (SCR increase to CS+) were not significantly associated although a trend towards association was observed . Neither affective measure was associated with any of the executive function measures . Mediation analyses showed that the bias corrected confidence intervals for the path coefficients did not cross zero for both models , consistent with a significant indirect effect of COMT genotype on aggression , poorer fear‐related empathy and greater failure to condition to an aversive stimulus (CS+) as assessed by skin conductance responses. We found that in this ADHD sample, measures of executive function did not predict aggressive outcomes, whether defined categorically in terms of clinical diagnosis or dimensionally as aggressive scores, whereas affective empathy, that is response to others' emotions  and reduced autonomic responsiveness in the conditioning experiment did. This was not explained by impaired ability to understand others' emotions (cognitive empathy). Mediation analysis including the intermediate phenotypes indicated that the Val allele had a significant indirect effect on aggression via emotional (fear empathy and fear learning) rather than executive control mechanisms.The results of this study once again show pleiotropic effects of COMT Val158Met predicted aggression/antisocial behaviour, performance on the available measure of executive function and a questionnaire measure capturing emotion/social cognitive items, the link between genotype and aggression was mediated via the measure of emotional/social cognitive function. The present study focused on patients and utilised static and dynamic task‐based assessments of emotion/social cognitive processes of the type judged to be captured in the original questionnaire. The findings not only suggest it is emotional processes rather than executive dysfunction that mediate links between genotype and aggression but also more specifically that these involve differences at a physiological level as well as in terms of reported experiences and appear to be specific to the emotion of fear. In the previous cohort study  , we adjusted for age and IQ, and the findings were not explained by comorbid anxiety/emotional problems. As these were typical adolescent clinic patients, none were drug naive and treatment could have reduced symptom levels in some thereby reducing power to detect associations with aggression. Our sample size while much larger than previous lab‐based cognitive and psychophysiological studies of adolescent patients, was small for a genetic investigation and included males only because of known Val158Met polymorphism on outcome and mediators, which cannot be disaggregated from causal links using a cross‐sectional design. Future prospective studies need to establish whether the observed emotional mechanisms explain the emergence and worsening of aggression in ADHD. There will also be a need to test the contribution of other genetic and nongenetic risk factors.Longitudinal population studies have shown that impaired fear conditioning in early childhood (in those without ADHD) may predict involvement in antisocial behaviour in the general population  but not executive control mediate the link between Our findings suggest fear‐related processes might represent important links between genetic risk and aggressive outcomes in ADHD.Psychological interventions that address fear‐related processes could help establish whether this is one route by which genetic risk of aggression in those with ADHD can be reduced.Table S1. DSM‐IV aggressive conduct disorder symptoms.Table S2. Mean aggression, executive function, fear empathy and fear conditioning scores.Table S3. Comparisons of included and excluded cases [mean scores (standard deviations)] on different types of tests.Appendix S1. Further information on genotyping.Click here for additional data file.


Background: Studies investigating event-related potential (ERP) evoked in a Cue-Go/NoGo paradigm have shown lower frontal N1, N2 and central P3 in children with attention-deficit/hyperactivity disorder (ADHD) compared to typically developing children (TDC). However, the electroencephalographic (EEG) dynamics underlying these ERPs remain largely unexplored in ADHD. Methods: We investigate the event-related spectral perturbation and inter-trial coherence linked to the ERP triggered by visual Cue-Go/NoGo stimuli, in 14 children (7 ADHD and 7 TDC) aged 8 to 12 years. Results: Compared to TDC, the EEG dynamics of children with ADHD showed a lower theta-alpha ITC concomitant to lower occipito-parietal P1-N2 and frontal N1-P2 potentials in response to Cue, Go and Nogo stimuli; an upper alpha power preceding lower central Go-P3; a lower theta-alpha power and ITC were coupled to a lower frontal Nogo-N3; a lower low-gamma power overall scalp at 300 ms after Go and Nogo stimuli. Conclusion: These findings suggest impaired ability in children with ADHD to conserve the brain oscillations phase associated with stimulus processing. This physiological trait might serve as a target for therapeutic intervention or be used as monitoring of their effects.  Attention Deficit/Hyperactivity Disorder (ADHD) is a neurodevelopmental disorder affecting 3–7% of school-age children . The maiNeuroimaging studies have shown alterations in the neuronal connectivity ,13,14 anp = 0.48, Mann-Whitney U Test), in gender ratio (Chi-square (1) = 1.17, p = 0.28), and comorbidities (Twenty six children aged 8 to 12 years were enrolled in the study (14 with ADHD and 12 TDC). Children with ADHD were recruited consecutively from the pediatric neurology outpatient clinic of Hôpital Universitaire des Enfants Reine Fabiola (HUDERF) in Brussels, Belgium. Diagnosis of ADHD was made by multidisciplinary team including pediatric neurologists and neuropsychologists according to DSM IV-TR. If the child was treated by medication (methylphenidate), this was stopped 48 h before the experimental process. TDC were recruited from primary mainstream schools, and were screened by neuropsychologists of the team. In addition to the neuropsychological assessment, each child performed the Wechsler Intelligence Scale for Children , and all parents were asked to fill in the Child Behavior Checklist . Exclusbidities . The expThe subject sat comfortably at 120 cm in front of a 17-in computer screen, and performed a visual-cued Go/Nogo task adapted from . The CueRegarding behavioral measures, dependent variables were omissions , false alarms , reaction time (RT) and the RT variability. The RT variability, estimating the intra-individual variability, was calculated with the coefficient of variation (CV) of reaction times , a normaBrain electrical activity was recorded with an ASA EEG/ERP system  from 14 channels , embedded in a waveguard cap (10–20 system), referred to the mean of the two mastoids and connected to the ground electrode. EEG activity was recorded at a sampling rate of 512 Hz . Eye movements were monitored using two bipolar recordings: one between each outer eye canthus, and one between a supra orbital electrode and an electrode just below the lower lid on the right side. Impedances were kept below 10 kΩ and checked before each recording. Off-line data treatment and analysis were performed by means of EEGLAB software  ,44 and iA EEGLab design study was used for each stimulus to average data from all subjects. A time window of 500 ms before stimulus onset was used as baseline. Evoked potential (ERP), spectral perturbation (ERSP) and inter-trial coherence (ITC), time-locked on each stimulus , were calculated by averaging baseline corrected epochs extracted from −0.5 to 1 s of the stimuli onset. ERSP and ITC are both time–frequency measurements calculated by means of fast Fourrier transform (FFT), but the information they provide is different: ERSP measures variations in power spectrum at specific frequency ranges of ongoing rhythms at specific periods of time and frequency range ,50. A coz = −2.17, p = 0.029), but no difference was found in commission to Cue  and NoGo  stimuli. We noted no significant differences in time reaction between ADHD and TDC . However, ADHD = 0.353 ± 0.087 s, CVTDC = 0.245 ± 0.050 s; z = 2.43, p = 0.015).There were more omissions to the Go stimulus in children with ADHD than TDC (p < 0.01) in children with ADHD compared to TDC. In the frequency domain, we observed a smaller ITC of theta (4.5–7 Hz) oscillation, that reached significant threshold (p < 0.05) between 260 and 420 ms after the Cue stimulus. At the same latency, high beta-gamma frequency showed a lower power and higher ITC in ADHD compared to TDC. Over central regions, we showed no significant difference between group in ERP, as well as in frequency domain, in response to the Cue stimulus. Concerning frontal regions, group analysis showed a lower N1 and higher P2 amplitude in ADHD than TDC (p < 0.05). These were coupled by a lower alpha power (p < 0.05) and ITC (p < 0.05) in children with ADHD compared to TDC. Group analysis over the posterior regions  showed tp < 0.05). In these regions, theta power and ITC were lower around 350 ms. Over central regions (p < 0.01) in children with ADHD compared to TDC. Moreover, while TDC showed an alpha (7–13 Hz) ERD starting at about 250 ms after the Go stimulus, this was not observed in children with ADHD (p < 0.05), and was coupled to a smaller ITC of alpha oscillation in ADHD than in TDC group (p < 0.01). Group analysis in frontal regions showed in children with ADHD compared to TDC, a lower N1 and higher P2 amplitude (p < 0.05) with at the same latency, a lower alpha power (p < 0.05). Finally, we revealed at about 600 ms in all regions, that gamma power was lower in children with ADHD compared to TDC. Concerning Go condition, ERP analysis showed a lower P1-N2 and lower P3 potential over posterior regions in children with ADHD compared to TDC  and ITC (p < 0.01) in ADHD group compared to TDC. Finally, we observed a significant high-beta/low-gamma ERD (p < 0.05) and a higher gamma ITC (p < 0.05) between 350 and 600 ms over all regions in children with ADHD, compared to TDC. In response to the Nogo stimulus, we found over posterior regions a lower P1-N2, with at the same latency a higher alpha power and lower alpha ITC in children with ADHD compared to TDC. Over central regions, although ADHD group seemed get a higher N3 than TDC, we observed no significant difference in ERP between groups. However, we found a lower theta power and ITC in children with ADHD compared to TDC at about 300 to 400 ms. Frontal N3 over anterior regions was lower in ADHD with respect to TDC group at about 300 ms  encodes a selective-gating mode maintaining the information previously stored in memory . Recent A last result from our data concerning Cue, Go and Nogo conditions concern a decrease of alpha power and ITC in frontal regions concomitant to a decrease of N1-P2 potentials in children with ADHD, compared to TDC. Alpha oscillation has been interpreted as reflecting global inhibition of the cortex, improving behavioral performance by facilitation of the cognitive control ,81,82,83In conclusion, this study showed that ERP studies must be analyzed during EEG dynamics, in order to better approach the mechanisms that underlie neural processing in ADHD. In relation to this, we found, in children with ADHD compared to TDC, that in Cue, Go and Nogo conditions: (1) reduction of occipito-parietal P1-N2 components was coupled with a decrease of theta ITC ; (2) reduction of frontal N1-P2 components was coupled with a decrease of alpha power and ITC; (3) an overall decrease of high-beta/low-gamma power occured 300 ms after stimulus (this was coupled with an increase of gamma ITC in the Nogo condition); and (4) in the Go condition, the decrease of P3 was preceded by a high alpha power and a small alpha ITC. This points to impaired ability in conserving the phase of brain oscillations associated with stimulus processing in a Go/Nogo paradigm in various frequency bands. This physiological finding might serve as a target for therapeutic intervention, or be used as monitoring of their effects. This study also paves the way for further investigations comprising the high EEG density and source localization approach.


In 2005, Nigeria changed its policy on prevention of malaria in pregnancy to intermittent preventive treatment with sulphadoxine-pyrimethamine (IPTp-SP). Indicators of impact of effective prevention and control of malaria on pregnancy (MIP) are low birth weight (LBW) and maternal anaemia by parity. This study determined the prevalence of LBW for different gravidity groups during periods of pre- and postpolicy change to IPTp-SP. Eleven-year data were abstracted from the delivery registers of two hospitals. Study outcomes calculated for both pre- (2000–2004) and post-IPTp-SP-policy (2005–2010) years were prevalence of LBW for different gravidity groups and risk of LBW in primigravidae compared to multigravidae. Out of the 11,496 singleton deliveries recorded within the 11-year period, the prevalence of LBW was significantly higher in primigravidae than in multigravidae for both prepolicy (6.3% versus 4%) and postpolicy (8.6% versus 5.1%) years. The risk of LBW in primigravidae compared to multigravidae increased from 1.62 (1.17–2.23) in the prepolicy years to 1.74 (1.436–2.13) during the postpolicy years. The study demonstrated that both the prevalence and risk of LBW remained significantly higher in primigravidae even after the change in policy to IPTp-SP. Malaria infection during pregnancy is a major public health problem in tropical and subtropical regions of the world. In most endemic areas of the world, pregnancy remains a high-risk factor for malaria infection . MalariaThe African Roll Back Malaria (RBM) summit in April 2000 adopted the Abuja declaration. The declaration entailed that regional leaders be committed to ensuring that at least 60% of pregnant women in malaria-endemic communities have access to effective prevention and treatment of malaria by the year 2005 . The sumSulfadoxine-pyrimethamine SP is the drug currently recommended by the WHO and also by the Nigerian Malaria Prevention and Control Guideline for the IPTp strategy because of its safety, efficacy, and other advantages , 12, 13.The study was a retrospective study during a period of 11 years (2000–2010).Two hospitals in two different geopolitical zones of Nigeria—Bishop Shanahan Hospital (BSH), Nsukka, and General Hospital, Calabar—were conveniently used for the study. BSH is a Catholic Mission Hospital located in the southeast region of Nigeria. It is a 150-bedded hospital that serves the immediate environs. It also has been serving as a referral centre for the surrounding communities since 1930. General Hospital, Calabar, is a government-owned secondary healthcare facility located in the south-south region. It is a 100-bedded hospital that has been in existence since 1991.All available and legible entries in the delivery registers for the years 2000–2010 were abstracted . The prevalence of LBW for different gravidity groups during periods of pre- and postpolicy change to IPTp-SP was determined through analysis of retrospective hospital data from delivery registers . The delivery register data covered a period of five years before SP-IPTp policy (2000–2004) and six years after SP-IPTp policy (2005–2010).Data were entered directly into an Excel spreadsheet specially prepared to collect relevant data from the registers.Birth weights were categorized as LBW (≤2.5 kg) or normal weight (>2.5 kg). Chi-square analysis was used to compare the prevalence of LBW in primigravidae against multigravidae. Logistic regression was used to determine the association between LBW and gravidity during the pre- and post-policy periods. This was done by calculating the odds ratio before and after the policy change and also the yearly odds ratio for the eleven-year period. These analyses were done using SPSS version 16 statistical software.t-test, respectively. These last analyses were carried out using GraphPad® software. The criterion for statistical significance was set at p < 0.05.Furthermore, the significance of the changes between the pre- and postpolicy periods was evaluated for the prevalence of LBW for different gravidity groups using chi-square and for the calculated odds ratio using independent student's The delivery registers show a total of 11496 mother-baby(ies) delivery pairs between 2000 and 2010 in the two hospitals assessed. Of these, 11249 (97.85%) were singleton deliveries and were used in further analysis of the birth weight data. The mean maternal age in years was 27.90 ± 5.345, while the mean birth weight in kg was 3.26 ± 0.563. The prevalence of LBW among this delivery cohort was 6% (640). Other demographic and obstetric characteristics of mother-baby pairs from the delivery registers are summarized in p < 0.001). On the other hand, the prevalence of LBW deliveries was significantly higher amongst primigravidae in all years except two years, during the postpolicy years (2005–2010) (p < 0.001) and after policy change (2005–2010)   was only significantly higher amongst the primigravidae in 2001  . Present< 0.001) .p = 0.7075] was recorded across policy year.Presenting the years into two blocks, pre-policy years (2000–2004) and post-policy years (2005–2010), Higher prevalence and risks of LBW deliveries were recorded in primigravidae, especially during the postpolicy years (2005–2010). This finding probably emphasizes the excess risk of this adverse outcome in primigravidae. Primigravidae have been reported to have increased susceptibility to malaria infections than multigravidae  and thusApart from malaria, there are other social and environmental factors that might also affect the prevalence of LBW deliveries. These include, but not limited to, maternal smoking, high blood pressure or preeclampsia, nutritional status of the mother, sex of the baby, number of antenatal clinics visits, maternal anaemia, maternal age, and other maternal infections like HIV , 17. Of The two variables, maternal anaemia and preeclampsia, were the possible cofounders of the results obtained in this study. Unfortunately, the results of the study could not be adjusted for these possible cofounders as they were not measured due to the retrospective nature of the study and unavailability of these variables in the study instrument used. Maternal anaemia, however, has a closely associated incidence with malaria in endemic areas like Nigeria and is thus unlikely to have any major effect on the sensitivity of the indicator at a population level. Preeclampsia—a pregnancy-specific disorder characterized by hypertension and proteinuria, with or without edema—on the other hand has a very low global prevalence ranging from two to ten percent of live births in developing countries . RecordsAnother important risk factor contributing to LBW deliveries that might preferentially affect primigravidae is teenage pregnancy. A high proportion of teenage primigravidae in a population would be expected to increase risk estimates. However, an overall low prevalence of women aged less than 18 years of age (1.8%) was recorded in this study and this could not have contributed to the high odds of LBW deliveries observed.Other risk factors for LBW deliveries like smoking, nutritional deprivation, and sex of the baby do not have such parity-specific effect on fetal growth as malaria and, therefore, might not have possibly contributed to the significantly increased odds of LBW deliveries among primigravidae, especially during the postpolicy period.A similar study in Malawi evaluating changes in birth weight indicator reported a slight increase in odds of LBW deliveries amongst primigravidae from 2.58 to 2.65 after a policy change from chloroquine to SP. This increase in odds of LBW deliveries in primigravidae, notwithstanding, was accompanied by reductions in the percentage of babies born to primigravidae and multigravidae who had LBW deliveries. The authors, therefore, concluded that since the slight increase in odds of LBW deliveries amongst primigravidae was also accompanied by significant fall in prevalence of LBW deliveries in both gravidae, the change to SP had produced some improvement in birth weight outcomes, even with incomplete regimen . This waAs surprising as our results were, poor implementation of effective interventions has been recognized as an important culprit of failure with such interventions. As of 2010, which was the last year of our analyzed data, the national coverage rate of at least two SP doses was very low (13.2%) . UnfortuThis study was not without limitations. A major limitation was in terms of unavailability or low quality of data at the health facility. Utilization of individual antenatal care folders of these pregnant women would have yielded data on the other impact indicator, prevalence of maternal anaemia by parity. It also would have been possible to assess the actual use of chloroquine or IPTp-SP among these women and their coverage rates rather than making assumptions of use based on the policy in existence during the years assessed. The study, on the other hand, explored a novel method of analyses using simple routinely collected health facility data to assess the impact of malaria prevention and control in pregnancy.The study demonstrated that there was no reduction in the risk of LBW in primigravidae when compared to multigravidae despite the change in policy to IPTp-SP. Rather, the postpolicy period recorded increases in both the excess risk of LBW in primigravidae, compared to multigravidae, and the prevalence of LBW among primigravidae. These are strong pointers that the impact of policy change to IPTp-SP on the prevalence of LBW has not been positive at best.