The primary objectives of this study were to investigate how adult patients with ADHD coped with their symptoms prior to diagnosis and treatment, what skills and compensation strategies they had developed and what their self-perceptions of these strategies were.We used a qualitative approach to analyze interviews with 32 outpatients of a specialty care unit at a university hospital.Patients reported frequent use of diverse compensatory strategies with varying degrees of effectiveness. These were classified into five categories . In certain circumstances, ADHD symptoms were even perceived as useful.Before diagnosis and treatment, patients with ADHD may develop a variety of skills to cope with their symptoms. Several of these skills are perceived as helpful. Knowledge of self-generated coping strategies may help better understand patients and their histories and thus facilitate patient cooperation. Moreover, knowing ways in which such patients cope with their symptoms may help elucidate reasons for late or under-diagnosing of the disorder. Attention-Deficit/Hyperactivity Disorder (ADHD) was once thought to be a transient childhood disorder . During The core symptoms of ADHD often manifest differently in adults than in children . HyperacThe cognitive deficits at the core of the disorder may mean that patients have limited resources for coping with daily situations , leadingStimulant medications are used as first-line agents in the treatment of adult ADHD  and haveIt is recognized that many adults with ADHD are not diagnosed as children and often come into contact with psychiatric services only because of co-morbid disorders. Asherson et al. discussed several reasons for under-diagnosing of ADHD , among tData from psychotherapy research supports the notion that teaching coping strategies and skills may improve psychosocial functioning in individuals with ADHD. Though patients may present with heterogenous levels of impairment–possibly because of the successful use of compensation strategies resulting in adaptive behavior –there haYoung et al. found a correlation between cognitive ability and coping in patients with ADHD compared to healthy controls, where personality factors and prosocial behaviour were also associated with coping . It has The development of coping behaviour and the identification of maladaptive coping is central to cognitive-behavioural treatments . KnowledIn this qualitative study, we investigated the skills and coping strategies adults with ADHD reported using before having been diagnosed or treated.For this study we used an exploratory qualitative approach and conducted a series of semi-structured interviews with adult patients with ADHD that had previously been referred to Zürich’s psychiatric university hospital for diagnosis and treatment. Participants were recruited following purposeful sampling procedures among outpatients being treated in a specialized unit for ADHD diagnosis and treatment at the university hospital. The cantonal ethics committee of Zürich approved the study (Application Nr. E-04/2005).We included subjects aged at least 18 years with a diagnosis of ADHD according to the 10th revision of the International Classification of Diseases  and withAn appointment for the interview was made by telephone by a member of the research group. All interviews were conducted outside the treatment setting by a member of the research group not involved in treatment and unknown to the participant to avoid a response bias. The participants were told, that both interviewers had experience in ADHD treatment and diagnostics, that AB worked in the hospital’s Division of ADHD Research and that AB and CC were interested in ascertaining how ADHD patients coped with their disorder and their opinions about several related topics. The interviews were not made available to the treating psychiatrists. Subjects did not receive any compensation for their participation.A semistructured, flexible, self-developed interview was used to explore the coping strategies participants reported using prior to diagnosis and treatment as adults. The use of a semistructured interview is common in qualitative research and allows the interviewer to adapt to the answers of the interviewee and to further explore interesting themes –53. SampInterviews were conducted in Swiss German, a dialect of Alemannic origin spoken in the German speaking parts of Switzerland. The interviews were conducted on a one-on-one basis by AB  and CC , both psychiatrists  with experience in ADHD treatment and qualitative research working at the time in Zürich’s psychiatric university hospital. Meeting outside the regular treatment setting in offices of outpatients clinics allowed for an atmosphere in which participants could speak freely.Interviews were started with open-ended, broad, general questions intended to encourage the interviewee to talk freely about his views and experiences . Non-judInterviews were digitally recorded using Olympus DS-7000 and then transcribed verbatim into Standard German. Whereas Swiss German is commonly only spoken, Standard German is traditionally used in writing and transcription, which is why all interviews were automatically written down in Standard German. Coding and analysis of data was done manually using a word processor (Microsoft Word for Windows 2013). After removing identifying information, all transcripts were assigned a code number. The transcripts were not returned to the participant. There were also no repeat interviews.Coding was done according to Mayring’s qualitative content analysis , which eRecruitment was ceased after saturation had been reached. Saturation is commonly defined as the point when no new themes can be found.Appropriate quotes were selected for the manuscript to validate the research findings and translated into English by CC. Back-translation by AB and ML and consequent discussion in the research group ensured accurate translations. ML chose the nearest translation when consensus could not be achieved. Where necessary, quotes were grammatically corrected to improve readability. Quotations were then proof read by a native English speaker.This study was reported according COREQ guidelines .Reported skills could be roughly organized into five categories: motoric, organizational, social, pharmacological and attentional . InteresInattention and impulsivity both contribute to organizational problems in ADHD patients. It follows then that the most frequently reported skills developed before entering treatment were of an organizational nature. Many patients had learned to use different ‘tricks’ and relied on external devices to improve organization. These skills were used for both activities of daily living and more often in work situations.Participants reported using checklists and electronic devices to plan or remind them of tasks and appointments.…because over the years, I have developed strategies to cope with day-to-day work, like really closely structured check lists for every work step. So that I don’t forget anything. Because otherwise, even after three years in this job, I would still forget the correct procedures… VP11…No, just a reminder app. And in this app there is a number showing the tasks left over. Then I can see, that I have still got five things to do… VP11…My blackberry is my greatest treasure… VP13..I write down a lot of things and use a lot of electronic devices. Mobile phone, laptop, tablet, everything but notes, because I lose them. I always end up losing notes or I can’t find them, it’s difficult, that doesn’t work (laughs)… VP20Depending on the position at work, planning and organizing could also be delegated.… I have someone, who takes care of making appointments. A secretary… VP3Several participants reported using special procedures to better cope with impulsivity, aversion to details and attentional problems.… First, I only work with workmen that work on call, without paper. Everything without paper. With people who think like me, decide like me… VP8… No paper… I wouldn’t ever even write a letter to my lawyer to give the instructions, ever… VP8Several participants dealt with attentional problems and restlessness by changing tasks. They claimed this helped them to maintain attention and productivity.…So if I can’t keep at what I am doing, then I don’t just stare into space or do something unnecessary. I do something else that I had planned on doing, so I can keep a high productivity… VP13This changing of tasks was perceived as enjoyable. Apparently, such working arrangements were not always consciously sought out due to an awareness of symptoms.… That is probably why I stayed for so many years at the laboratory…I liked it there. I always had interesting tasks but they never took longer than half an hour. And then I could switch to another device and walk around and there was always something going on… VP12Two participants  reported working independently, which enabled them to plan in such a way, that they could maximize productivity and avoid problems due to loss of attention.Very rigid structures and detailed plans were seen as helpful or even indispensable by some participants. Particularly the former were perceived to be helpful in attaining higher levels of productivity.…My week is well planned. I know exactly, what is supposed to happen this week… VP6…If I compare my daily output with that of a normal person, then I achieve about 150%, just because of what I can compress into a day. And it’s clearly because I am totally structured… VP9… A rigid daily structure? Yes, even on weekends. I always go to bed at 10, that’s very important, because if I don’t, if I lose this, I start drifting. I get my confused days and I can’t concentrate anymore and I am never happy…of course I would like to sleep in sometimes, but I know, that it won’t be a good day then…VP9Such rigid structures were reported to be the result of a special educational effort by their parents. It might be surmised, that the parents had recognized the distinct difficulties of their children and adapted accordingly, maybe even without being conscious of the disorder per se.… Since I was little, it has been ingrained into me to have a structured daily routine. I don’t know, whether it’s because of that that I can perform on such a level…VP9Thorough planning considering every eventuality also helped reduce discomfort and dysfunctional impulsive reactions.… I have structured my daily routine myself and have developed strategies for a clear structure. I also always have a plan A, B, C and D. I just couldn’t cope with situations, that weren’t as I had expected, I used to flip. So to avoid this, I started thinking for example when I took the streetcar about when I had to exit and what to do, if I missed it…I just started thinking about all possible eventualities, so that I wouldn’t come up into a situation where I didn’t know what to do… VP6Hyperactivity is another characteristic feature of ADHD, often expressed in adults as restlessness and fidgeting. Physical activity has been said to attenuate some ADHD symptoms . Therefo… For instance, with sports too, I knew that it helped somewhat… VP7… I am more productive…As long as I have enough time to do sport. A lot of time for sport… VP9Even fidgeting was felt to increase productivity and functioning.… I move my foot the whole time, I’m not even conscious of doing it. But I believe that because of this hyperactivity, I can be very productive, when I concentrate… VP4Another approach to coping with attentional problems and restlessness was to restrict movement–sometimes even through physical restraints.… you tie yourself up (in a chair), so that you can’t stand up the whole time. like with a belt, a karate belt, so that you have untie yourself to stand up… it helps you remember, why you were sitting down in the first place… VP21Many participants had also developed strategies to manage distracting stimuli and maintain their attention. Several claimed to work better in environments with fewer stimuli, be it at night or in a cellar.… it begins when you understand, that there are fewer external stimuli at night, that you are not hungry and that other people are not doing anything…nothing happens, even on the internet, articles are actualized between 12 pm and 7 am… so I just worked at nights…studied at night… VP21… I used to study in the basement, on a table, it was cold and there wasn’t anything to distract me… VP14Similar approaches could also be found in social situations, where being in contact with several people at the same time could be perceived as stressful. One participant reported skillfully avoiding scheduling appointments with more than one person, so she could better focus her attention on one person and hide her attentional problems from her environment.… “Did you never notice, that I only made appointments with one person?”… and if there was an invitation for a bigger party, I always had an excuse, something plausible… VP12Solitude and environments with fewer uncontrollable stimuli were perceived as helpful in relaxing and were actively sought out.…nature in general. Just going for a walk or go to the lake or reading. Or, ehm, also cleaning up my place. I like cleaning up. It’s kind of satisfying, a little like cleaning up your thinking. It kind of helps to relax… VP7… and of course, to be able to cope well with being alone and to even need it at times… VP12Patients with ADHD often experience interpersonal difficulties due to inattention in conversations, fidgeting, forgetfulness or impulsive behaviour, resulting in blurting out opinions or interrupting conversations. Though the level of impairment in social situations and the level of perception of such problems remained unclear in the interviews, several participants reported the use of special strategies when dealing with others before initiation of therapy.One of the reported strategies was putting special care into being punctual.… My compensation strategy is to be overly punctual… VP15.. and such structures as always being early for an appointment. I am never late… VP6Since forgetfulness due to inattention or impulsive behaviour may be especially vexing for the environment, another strategy was to consciously avoid rigid commitments requiring special care:…what I always intuitively did, from early on, was to avoid any kind of dependence/commitment. That became a core principle, to never create any dependence because this brings about commitments. And these restrict me which leads in turn to conflicts… any kind of commitment, even a club membership, where you need to attend meetings five times a year, whatever, even that would have felt restricting…VP8Behavioural disinhibition was reported to have negative effects in social situations. These could be mitigated by socializing with a high number of friends and colleagues at the same time.…so by surrounding myself always with lots of people, it never attracted attention when I behaved specially obnoxiously. I always had a reputation for being elusive, for doing my own thing, for not being easily categorizable… I always knew, if I started to have contact like with only five people, in a narrow social environment, there would be trouble. Firstly, people would see through me. And secondly, it would be too restricting for me… VP8As expected, several participants reported themselves to be especially interesting, funny or entertaining for others–probably due to hyperactivity and impulsiveness. This might be seen as maladaptive behaviour. Alternatively, since it was several times reported as a positive trait, it might also represent an adaptive strategy that does not diminish social functioning per se, but allows the individual to better cope with high levels of restlessness and impatience. Also, being the center of attention in a group might negate problems of inattention in conversations.… I don’t need to drink, to be so funny or act drunkenly like those who really are. I can do so just as well without being drunk. And I can do it just like that, at once…VP1…They said, that I could entertain them the whole night, there was always something going on, I had always a lot of energy and was always ready to do something with them and I always had interesting things to tell… VP7Many participants reported having had experiences with psychotropic substances. The substances used were cocaine, THC, nicotine, MDMA, amphetamines, alcohol, caffeine, LSD, ‘magic mushrooms’ and benzodiazepines see . Some ofCaffeine and alcohol were perceived as having a calming effect.…I used to drink three to five coffees a day. Nowadays I drink only to enjoy, but then it was purely functional, to calm myself… VP2…Without Ritalin (Methyphenidate) it was like that: I was standing here and there where like a lot of railways coming towards me and each one had a train on it driving towards me. There were so many impressions, so many requirements or ideas, I felt overwhelmed and I turned around and did nothing. Mainly I used to drink alcohol then, to calm these feelings… VP19Cocaine was also reported to have a calming effect, to enable sleeping and to enhance concentration.… Cocaine calmed me down extraordinarily… where others got started, I was just happy to find peace from myself… VP4… What worked, was that I slept better (with cocaine)… Interestingly, I noticed that I was calmer and could sleep better, it just was more pleasant, in a way… VP8… During times of partying I noticed, that there was another effect of cocaine, I liked it, but I couldn’t say what it was exactly. And I started taking it regularly, not only at parties. And then, when I was 17 and in my apprenticeship we had an exam and I didn’t even know about what and I hadn’t studied for it. I went in and got a top score, even though I didn’t know beforehand, what this test was about. And I tried it again with cocaine and it worked again and I told myself, that I had to stop… VP11MDMA was considered to enhance cognitive performance.…My thoughts were totally clear, I could have achieved a top score in an exam. I was so clear in my head. And I could sleep. I could take greater amounts, had to take greater amounts, to make it work… VP6THC helped to relax, facilitate sleep and enhance concentration in some cases.…Because THC is also something, that helps me relax. And helps me sleep, of course…VP7…What I always continued doing, was smoke pot, and I still do so every evening. To sleep, so I can sleep…VP11…And I took all my exams while I was stoned. And yes, I could concentrate better or at least I thought so. And I did a lot of work like that, because I felt that it was easier this way… VP12Nicotine helped in sustaining attention and had a calming effect.…I need so much kick from nicotine, to focus somewhat. And it doesn’t work for long. That means only for about a minute and then I need to go again…VP15… How do you treat inner unrest? By smoking cigarettes. It’s like a tingling sensation inside of you. And when I feel it, I go smoke a cigarette. I need to distract myself so I don’t concentrate on that…VP11Amphetamines were perceived as having a beneficial effect on motivation and prioritizing.… And then I tried out speed, and it was just what I needed. I was more motivated and the whole way to get there just seemed like no big deal, and you recognized, I’ve got to do this and then this and then I will have reached my goal and have good grades…VP21To the authors‘ knowledge, this is the first study focusing on skills developed by adult patients with ADHD prior to their diagnosis and their perceptions of these compensatory strategies. Reported skills could be classified into five categories .The first skill group–organizational skills–was reported most often and reflects the common problems of ADHD patients in organization. Reported strategies highlight the benefits of using modern technology, i.e. smartphones, electronic calendars, reminder apps, etc. and synchronizing them. The developing of particular routines to accommodate typical ADHD behaviours was also seen as helpful. Additionally, the option to change tasks when attention started to diminish was seen as beneficial towards maintaining productivity. Creating special work arrangements, such as using as little paper as possible–because paper can easily be lost–or simplifying hiring and contracting procedures to the point of just having to make one phone call, minimized the risk for procrastination and was seen as well worth the effort.Tellingly, some participants stressed the need for maintaining rigid structures and claimed that this allowed them to function more efficiently. In this way they could also avoid boredom and mood shifts.The group of motor skills comprised mainly the use of physical activity. It was perceived as beneficial and for some indispensable in maintaining attention and productivity. A contrasting approach was to restrict movement by binding oneself to the chair to remind the participant of the task at hand when his attention shifted.The third category of skills included strategies to manage stimuli and attentional problems. Participants reported seeking out environments with relatively few stimuli (i.e. cellar) or confining themselves to working at night. One participant used a similar approach in social life and avoided meeting several people at the same time. Relatively stimulus-poor environments were not only sought out to maximize productivity, but also for their calming and relaxing effect.The fourth category was comprised of adaptive social skills. These varied greatly and included taking care to be punctual, avoiding commitments demanding too much engagement from the participant or frequent contact with the same people to diminish the impact of social functional impairment on relationships. Since several participants saw themselves as funny, interesting or entertaining and self-reported these characteristics as positive, we decided to include these traits. For some individuals it may represent the best available way to cope with impulsiveness, restlessness and attention problems in social interaction. At the same time, being the focus of attention may have a positive effect on self-esteem, a common problem in ADHD patients . Of specThe last category comprised the use of psychotropic substances to ameliorate ADHD symptoms. Whereas most patients reported experiences with substance use, only some spontaneously related their substance use with attempts to reduce ADHD symptoms and reported positive effects of caffeine, nicotine, cocaine, MDMA, alcohol, THC and amphetamines on their symptoms.In our sample we found that many participants were conscious of having used particular strategies to cope with ADHD symptoms prior to diagnosis and treatment. A wide range of coping skills of varying degrees of effectiveness support the assumption, that patients with undiagnosed ADHD spontaneously generate skills they implement regularly.Although there is a dearth of research on coping mechanisms of patients with ADHD, the main skill groups are consistent with the current state of knowledge, even if some may seem more exotic. Many of the reported organizational skills are reminiscent of psychotherapy programs, as is the management of external stimuli , 58, 59.Whereas some compensation strategies clearly aimed at controlling symptoms or indirectly compensating them, many participants also reported seeking out special environments or–broadly speaking–adapting them in such a way, that allowed them to function well despite their symptoms. Changing the environment to suit the needs of patients is also consistent with rehabilitation recommendations found in therapy manuals . InteresConsidering that many ADHD symptoms are ego-syntonic and participants in our study had not been prepared for the topics of the interview, it can be assumed they did not report all their coping strategies, as they may not have even been aware of the extent of their adaptation. It may be, that on a repeat interview or with due preparation for the topic some patients may recount more adaptive mechanisms.Furthermore, our findings only include concrete coping skills. More general abilities of problem solving, stress management, assessment of problems or help-seeking behaviour as reported in a previous study about coping strategies by Young et al.  were notThe results of this study provide insight into how coping strategies are perceived by patients with ADHD, which skills they spontaneously generate and which they find helpful. From a systemic and functional perspective they also underline the positive aspects of ADHD symptoms and behaviours in a particular environment. Furthermore, they may also shed light on the mechanisms underlying late and under-diagnosing. Considering some of the reported, well-developed skills , it may be, that some core symptoms may ‘hide’ behind well-developed coping strategies or particular working environments and this decreases self-awareness of symptoms. Such mechanisms might hamper diagnostic efforts. Lastly, these findings about spontaneously developed coping strategies improve insight and understanding of the development of patients with ADHD during late adolescence and adulthood. In turn, this might help further therapeutic alliance and patient collaboration and may even serve as concrete guides for therapeutic interventions.


Mage = 10.9 years, range 6.2–15.6; Mageadoption = 3.0 years, range 0.8–6.9) completed questionnaires regarding ADHD symptoms, pre-adoptive risk factors, attachment problems, conduct problems, and executive functioning deficits. Bayesian evaluation of informative hypotheses showed that Polish adoptees had increased levels of ADHD symptoms, compared to Dutch children in the general population. Time in institutional care, early deprivation, and prenatal alcohol exposure were not associated with ADHD symptoms. ADHD symptoms in Polish adoptees were more strongly associated with attachment problems and executive functioning deficits, but less strongly with conduct problems, compared to ADHD symptoms in non-adoptees. Furthermore, ADHD symptoms were more equally distributed among boys and girls than they are in non-adopted children. The findings indicate that Polish adoptees and their adoptive parents need special attention and support. The dissimilarities between ADHD symptoms in Polish adoptees and non-adoptees might indicate a different underlying causal mechanism, which may have important implications for clinical practice.Although high rates of attention-deficit hyperactivity disorder (ADHD) symptoms have been observed among internationally adopted children, research on these symptoms in Polish adoptees is lacking. Therefore, we examined ADHD symptoms in Polish adoptees and their relationship to pre-adoptive risk factors, that is, time in institutional care, early deprivation, and prenatal alcohol exposure. We further compared the association patterns and gender distribution of ADHD symptoms in children adopted from Poland to those reported in the literature for ADHD symptoms in non-adopted children. Dutch adoptive parents of 121 Polish adoptees (52% boys;  Internationally adopted children have shown to be at higher risk for behaviour problems than non-adopted children  of ADHD symptoms in Polish adoptees to those in non-adopted children. We used a Bayesian approach to overcome the statistical limitations due to small sample size that were encountered in previous adoption studies  examine the occurrence of ADHD symptoms in Dutch children adopted from Poland and their relationship to pre-adoptive risk factors. Based on previous research, we hypothesized that Polish adoptees would show increased levels of ADHD symptoms, compared to Dutch children in the general population. We more specifically expected that Polish adoptees would display higher levels of attention deficits, hyperactivity, and impulsivity. In addition, we hypothesized that more time in institutional care, early deprivation, and prenatal alcohol exposure would predict higher levels of ADHD symptoms as well as higher levels of attention deficits, hyperactivity, and impulsivity. A second aim of this study was to (2) compare the association patterns and gender distribution of ADHD symptoms in children adopted from Poland to those reported in the literature for ADHD symptoms in non-adopted children. We expected that ADHD symptoms in Polish adoptees would be more strongly associated with attachment problems and executive functioning deficits, but less strongly with conduct problems, than ADHD symptoms are in non-adopted children. Finally, we expected that ADHD symptoms in Polish adoptees would be more equally distributed among boys and girls than these symptoms are in non-adopted children.M = 10.9 years, SD = 2.7; 52% boys). The children were adopted by 71 Dutch couples, who adopted 1 to 4 Polish children . Age at adoption ranged between 0.8 and 6.9 years . Questionnaires were completed by the adoptive mothers (73%), adoptive fathers (8%) or both (19%).The current study was part of a larger project on the development of Polish adoptees in the Netherlands Knuiman . The eli2 goodness-of-fit analyses showed that the two groups did not differ regarding gender and early deprivation.Attrition analyses were performed to test whether the children that only participated in wave 1 differed from the children that participated in both wave 1 and 2 on any of the research variables. Results of univariate analyses of variance (ANOVA) showed there were no significant differences between the two groups concerning age, time in institutional care, and conduct problems. Furthermore, results of χn = 181) received an invitation letter to participate in the study. Letters were sent to the parents by the collaborating adoption agency. Parents that did not respond to our invitation within 2 months, received a reminding letter. After agreeing to participate, parents were requested to complete the questionnaires. All procedures performed in this study were in accordance with the ethical standards of Utrecht University, the Netherlands.Dutch adoptive parents of all children adopted from Poland between January 1999 and December 2006 , the time children had spent in institutional care (in months), the occurrence of early deprivation , and the occurrence of prenatal alcohol exposure .At wave 1, adoptive parents reported on children’s gender, date of birth, and date of adoption. Pre-adoptive risk factors were also reported by adoptive parents, including the occurrence of institutionalization (the child does not act in this way to 4 = the child acts in this way very often [every day]). An ADHD total score was computed by summing the scores on the three subscales, with a higher score implying more ADHD symptoms. Raw AVL scores were transformed into decile scores, which were derived from the Dutch AVL norm group  was used for comparison. The Dutch Testing Committee judged the validity and reliability of the AVL total scale and subscales as good, except for the criterion validity and norms, which are considered acceptable , supporting the construct validity of this questionnaire. The internal consistency was good in this sample, with Cronbach’s alpha being 0.94 for the total scale and 0.86–0.88 for the subscales.The ADHD-questionnaire [ADHD-vragenlijst] . A total score for attachment problems was computed by summing the item scores, with a higher score implying more attachment problems. The internal consistency and validity of the GIH are found to be good . As described by Achenbach and Rescorla . A global executive composite score was computed by summing the scores on the eight subscales, with a higher score implying more deficits in executive functioning. The internal consistency and construct validity of the Dutch BRIEF are reported to be good , to decrease the probability that the results were obtained by chance. Third, studies with an adequate methodological design  were included. Fourth, we selected studies that were published recently (2005 or later). Based on these criteria, a total of 17 studies were excluded.The informative hypotheses regarding the association patterns of ADHD symptoms were based on studies that reported the parameters  in which we were interested. Additionally, we used four inclusion criteria to select the studies. First of all, we limited our literature review to studies among children in the general  population, as one of our aims was to compare ADHD symptoms and their association patterns in Polish adoptees to those seen in children in the general Dutch population. Second, we included studies with a relatively large sample size (Mcorrelation = 0.33).To examine the association between ADHD symptoms and co-occurring problems, correlational analyses were performed. Concerning attachment problems, we expected that the correlation coefficient between ADHD symptoms and attachment problems would be larger than 0.33, based on Pinto et al.  and ThorMcorrelation = 0.68). We expected that the correlation coefficient between ADHD symptoms and executive functioning deficits would be larger than 0.33, based on Scholtens et al. (Mcorrelation = 0.33). To examine the gender distribution of ADHD symptoms, a linear regression analysis was performed with gender as predictor . We expected that the standardized regression coefficient of gender would be smaller than 0.36, based on Ramtekkar et al. (n = 2704).We expected that the correlation coefficient between ADHD symptoms and conduct problems would be smaller than 0.68, based on Scholtens et al.  and Thors et al.  and Thors et al. . To our r et al.  and Thorr et al. . Both str et al.  was baseAs can be seen in Table Subsequently, we entered each set of informative hypotheses  in the software program BIEMS . The intraclass correlation coefficient was 0.16, indicating that 16% of the total variance in ADHD symptoms could be attributed to differences between families. The analyses including one child randomly selected per family yielded the same conclusions as the analyses including the total sample. Therefore, we decided to include the total sample of children in all analyses.To examine the level and predictors of ADHD symptoms, we first conducted the analyses with ADHD symptoms as the dependent variable. After that, we performed separate analyses with the subscales attention deficits, hyperactivity, and impulsivity as dependent variables. To control for dependency in the data (children nested within families), additional analyses were performed with one child randomly selected per family scale. One case was excluded from all analyses because of missing data on the AVL. In total, 62 cases were excluded from the analyses of pre-adoptive risk factors, because information was unknown to parents or missing (not missing at random). Results of ANOVA showed that the children that were excluded from the analyses of pre- adoptive risk factors did not differ from those included regarding ADHD symptoms. Seven cases were excluded from the analyses of conduct problems, because their age fell below the age range of the CBCL or more than 10% of the data on the CBCL was missing. One case was deleted from the analysis of executive functioning deficits, due to inconsistent scores on the BRIEF.Table In total, 40.0% of the Polish adoptees scored in the clinical (25.8%) or borderline range (14.2%), compared to 10.0% of the children in the norm group that scored in the clinical (5.0%) or borderline range (5.0%). The correlations between the three pre-adoptive risk factors were very weak or weak and did not point to multicollinearity. Since children’s age at adoption and at time of study were not related to ADHD symptom levels, these variables were not included in the remaining analyses.1vs2 > 201.00; BF1vs3 > 201.00). Similar results were found when testing the hypotheses separately for the subscales attention deficits, hyperactivity, and impulsivity, indicating that Polish adoptees scored higher than the Dutch norm group on all subscales.Results of the Bayesian evaluation of informative hypotheses for the level of ADHD symptoms are displayed in Table 2vs1 = 183.42). Posterior standardized regression coefficients of the predictors were close to zero .Results of the Bayesian evaluation of informative hypotheses concerning the predictors of ADHD symptoms are displayed in Table 1vs2 = 3.08; BF1vs3 = 71.20). As can be seen in the table, the posterior correlation coefficient was estimated at 0.51. Concerning conduct problems, it was found that hypothesis 1, assuming that the correlation between ADHD symptoms and conduct problems in Polish adoptees was smaller than 0.68, received most support in the data. Hypothesis 1 was about 18 times and 627 times more likely than hypothesis 2 and 3, respectively . For executive functioning deficits, it was found that hypothesis 1, assuming the correlation between ADHD symptoms and executive functioning deficits in Polish adoptees was larger than 0.33, received most support in the data. Hypothesis 1 was about 6800 times and more than 1,000,000 times more likely than hypothesis 2 and 3, respectively .Results of the Bayesian evaluation of informative hypotheses concerning the association patterns of ADHD symptoms are displayed in Table 1vs2 = 2375.89; BF1vs3 > 1,000,000). Similar results were found when testing the hypotheses separately for the subscales attention deficits, hyperactivity, and impulsivity, indicating the regression coefficient of gender was smaller than 0.36 for all subscales. In line with this finding, boys  scored only slightly higher than girls  on ADHD symptoms.Results of the Bayesian evaluation of informative hypotheses concerning the gender distribution of ADHD symptoms are displayed in Table The current study aimed to examine the occurrence of ADHD symptoms in Dutch children adopted from Poland and their relationship to pre-adoptive risk factors. As expected, children adopted from Poland showed increased levels of ADHD symptoms, compared to a Dutch norm group of children in the general population. Compared to this norm group, Polish adoptees were four times more likely to have ADHD symptoms at a clinical or borderline level. These results are in line with previous research indicating that children adopted from other CEE countries are more likely to show attention and hyperactivity problems, in comparison to non-adopted children (e.g., Abrines et al. Contrary to our expectations, time in institutional care, early deprivation, and prenatal alcohol exposure were not associated with ADHD symptom levels among Polish adoptees. This result is in contrast with previous research indicating that Romanian adoptees who had spent more time in institutional care showed more ADHD symptoms than children who had stayed less time in these institutions (Kreppner et al. Several explanations are possible for the lack of an association between ADHD symptoms and pre-adoptive risk factors in the current study. First, Polish adoptees had been exposed to multiple biological, prenatal, and early life risk factors prior to adoption (Knuiman et al. The second aim of this study was to compare the association patterns and gender distribution of ADHD symptoms in Polish adoptees to those reported for ADHD symptoms in research among non-adopted children. As expected, ADHD symptoms were more strongly associated with attachment problems in Polish adoptees than these symptoms are in non- adopted children. This finding is consistent with those of previous studies reporting that adoptees with ADHD symptoms displayed increased attachment problems (e.g., Abrines et al. These findings are supportive of earlier suggestions that the association patterns of ADHD symptoms in internationally adopted children might be different from those of ADHD symptoms in non-adopted children (e.g., Kreppner et al. Thus, our findings are inconclusive with respect to theory about ADHD symptoms in international adoptees. On the one hand, the finding that ADHD symptoms were not associated with pre-adoptive risk factors opposes the suggestion that ADHD symptoms in international adoptees would constitute a specific response to early institutional deprivation (Rutter et al. This study expanded previous work by focusing on ADHD symptoms in children adopted from Poland. The use of Bayesian statistics enabled us to overcome the statistical limitations related to small sample size often encountered in previous adoption studies (e.g., Groza et al. Additionally, we were able to include previous empirical findings in our informative hypotheses (Kluytmans et al. There were, however, some limitations to this study. First, we only considered the perspective of the adoptive parents to measure children’s functioning after adoption. Our sole reliance on parental report might have inflated the associations between the different behavioural measures, due to same-reporter variance. Future studies that include additional informants or methods, such as teacher reports or observations, may provide more reliable associations and a more comprehensive picture of children’s functioning. Second, the use of two less validated questionnaires might be seen as a limitation of the current study. Although the BRIEF is the most widely used parental rating of executive functioning, low correlations have been reported between this instrument and experimental tasks on executive functioning (e.g., Bodnar et al. However, many of our hypotheses received much more support than the alternative hypotheses. We therefore expect that small differences in the parameters that were included in our informative hypotheses would have yielded the same conclusions, based on our analyses.Furthermore, longitudinal studies on the functioning of Polish adoptees in adolescence and adulthood are recommended. It would be beneficial to examine how ADHD symptoms in this group of adoptees develop over time, together with their associated problems, such as attachment problems and executive functioning deficits. As longitudinal studies indicated that ADHD symptoms in Romanian adoptees persisted into early adolescence (Kreppner et al. The high rates of clinically significant ADHD symptoms indicate that Polish adoptees and their adoptive parents may benefit from professional care after adoption. Adoptive parents should receive support after their child arrives in the family. Providing assistance to these parents at an early stage may prevent that the ADHD symptoms of their children will aggravate and impair their functioning in academic or social domains. Long-term assistance could be achieved by monitoring the development of Polish adoptees and providing help to adoptive parents when needed.The atypical presentation of ADHD symptoms in this sample of Polish adoptees, in terms of association patterns and gender distribution, raises clinical issues. An important question is whether international adoptees with ADHD need a different clinical treatment than typically recommended for ADHD in non-adoptees (i.e., psycho-stimulant medication and psychosocial therapy; Wolraich Finally, the findings of this study will primarily apply to children adopted from Poland within the same time period. However, since the pre-adoptive backgrounds of CEE adoptees partially overlap, for instance regarding institutionalization (e.g., Miller et al. Children adopted from Poland were at higher risk for displaying attention, hyperactivity, and impulsivity problems than Dutch children in the general population. Their ADHD symptoms showed atypical association patterns, which might indicate a different underlying causal mechanism of ADHD symptoms in international adoptees. Moreover, the majority of the Polish adoptees had experienced institutionalization, early deprivation, or prenatal alcohol exposure prior to adoption. These findings demonstrate that Polish adoptees and their adoptive parents need special attention, so that these children can develop in an optimal way.


Preterm birth has been associated with an increased risk of attention-deficit/hyperactivity disorder (ADHD)–like symptoms and cognitive impairments similar to those seen in ADHD, including attention and inhibitory control difficulties. Yet data on direct comparisons across ADHD and preterm birth on cognitive-neurophysiological measures are limited.We directly compared 186 preterm-born adolescents to 69 term-born adolescents with ADHD and 135 term-born controls on cognitive-performance and event-related potential measures associated with attentional and inhibitory processing from a cued continuous performance test (CPT-OX), which we have previously shown to discriminate between the adolescents with ADHD and controls. We aimed to elucidate whether the ADHD-like symptoms and cognitive impairments in preterm-born individuals reflect identical cognitive-neurophysiological impairments in term-born individuals with ADHD.Go-P3 amplitude was reduced, reflecting impaired executive response control, in preterm-born adolescents compared to both controls and adolescents with ADHD. Moreover, in preterm-born adolescents, as in term-born adolescents with ADHD, contingent negative variation amplitude was attenuated, reflecting impairments in response preparation compared to controls. Although the ADHD group showed significantly increased NoGo-P3 amplitude at FCz compared to preterm group, at Cz preterm-born adolescents demonstrated significantly decreased NoGo-P3 amplitude compared to the control group, similar to term-born adolescents with ADHD.These findings indicate impairments in response preparation, executive response control, and response inhibition in preterm-born adolescents. Although the response preparation and response inhibition impairments found in preterm-born adolescents overlap with those found in term-born adolescents with ADHD, the preterm group also shows unique impairments, suggesting more wide-ranging impairments in the preterm group compared to the ADHD group. In the developed world, 8.6% of individuals are born preterm .ADHD is characterized by developmentally inappropriate and impairing levels of hyperactivity, impulsivity, and/or inattention.Although research has provided strong support for the link between preterm birth and ADHD, little is known about the underlying risk pathways. Cognitive performance data alone provide only indirect insight into covert processing as various covert mechanisms may result in indistinguishable overt performance on cognitive tasks. The study of event-related potentials (ERPs), which are electrical potentials generated by the brain in response to internal or external events such as stimuli and responses,Although countless ERP studies have been conducted in preterm-born infants in neonatal intensive care unitsOne of the most common cognitive tasks used to study attentional processing and response inhibition in individuals with ADHD is the cued continuous performance test (CPT-OX). The CPT-OX requires participants to detect target stimuli among a sequence of distractor stimuli. Omission errors  are assumed to represent impairments in sustained attention, whereas commission errors  are an index of response inhibition. ERPs associated with the CPT are the Go-P3, which is an electrical potential generated by the brain in response to the target stimulus, the NoGo-P3, which is an electrical potential generated by the brain in response to the distractor stimulus and reflects response inhibition, as well as the Cue-P3 and contingent negative variation (CNV), which occur in response to the cue stimulus and are thought to reflect attentional orienting to a cue and motor response preparation respectively. CPT performance is typically impaired in individuals with ADHD, who usually demonstrate increased reaction time variability, a greater number of OEs, and a greater number of CEs.36Direct comparisons on ERP measures between preterm-born individuals and term-born individuals with ADHD are scarce. One ERP study investigated attentional processing in very-low-birthweight children born preterm  with and without ADHD, as well as in term-born controls and term-born individuals with ADHD.We previously reported findings on ADHD case−control differences on cognitive and neurophysiological markers of ADHD. With the use of the CPT-OX, we demonstrated that sustained attention (indexed by omission errors), response inhibition (indexed by commission errors and NoGo-P3 amplitude), intraindividual fluctuations in reaction times (RTV), response preparation (indexed by CNV amplitude), and attentional orienting (indexed by Cue-P3 amplitude) successfully discriminated between adolescents with ADHD and controls.In the current study, we therefore aim to establish whether the cognitive impairments associated with preterm birth, including attention and inhibitory control difficulties, reflect neurophysiological impairments identical to those observed in term-born individuals with ADHD.t = −16.55, df = 178, p < .001, d = 2.53; t = −17.23, df = 178, p < .001, d = 2.94 respectively) and control group . The preterm group further demonstrated significantly higher ADHD symptoms and functional impairment than the control group . Although only 4% of the preterm participants were treated with stimulant medication, 47% of the participants with ADHD were treated with stimulant medication at the time of the assessment. A 48-hour ADHD medication-free period was required before assessments. Written informed consent was obtained following procedures approved by the London-Surrey Borders Research Ethics Committee (09/H0806/58) and the National Research Ethics Service Committee London—Bromley (13/LO/0068).The sample consisted of 186 preterm-born participants , 69 participants with ADHD  and 135 controls . The groups differed significantly in terms of age, IQ, sex distribution, gestational age (GA), and ADHD symptom scores . The ADHThe preterm group was recruited from secondary schools in Southeast England. All preterm participants had one full sibling available for ascertainment and were born before 37 weeks’ gestation. Siblings of preterm-born individuals were included in the preterm group if they were also born preterm (before 37 weeks’ gestation), to maximize the number of participants in the preterm group. Term-born siblings of preterm-born individuals were not included in this analysis. Most preterm-born participants were of European white descent (84.6%). The other ethnicities represented were British Asian (3.7%), mixed white and black Caribbean (2.1%), mixed white and British Asian (1.6%), Indian (1.1%), mixed white and Indian (1.1%), black Caribbean (0.5%), mixed black and British Asian (0.5%), and other (2.7%). Seven individuals from the preterm sample were excluded because medical birth records could not corroborate preterm status (GA ≥37 weeks). One individual was excluded because of an IQ of <70. Eight preterm-born individuals met diagnostic criteria for a research diagnosis of ADHD. Since here preterm birth is investigated as a potential risk factor for ADHD, preterm-born individuals who demonstrated high levels of ADHD symptoms were not excluded from the analysis  and secondary (aged 12–18 years) schools in the United Kingdom, aiming for an age and sex match with the ADHD sample. Control individuals and their siblings were included in the control group if they did not meet DSM-IV criteria for any ADHD subtype either in childhood or at follow-up.ADHD and control sibling pairs who had taken part in our previous researchExclusion criteria for all groups were IQ of <70, general learning difficulties, cerebral palsy or any other medical condition that affects motor coordination including epilepsy, as well as brain disorders and any genetic or medical disorder that might mimic ADHD. In addition, preterm birth was an exclusion criterion in the ADHD and control groups, because this study aimed to establish whether the cognitive impairments associated with preterm birth reflect identical neurophysiological impairments in term-born individuals with ADHD.We followed up the sample on average 5.8 years (SD = 1.1) after initial assessments. The ADHD and control groups were previously included in a study investigating ADHD case−control differences on cognitive and neurophysiological markers of ADHD persistence and remission.At follow-up, six participants from the ADHD−sibling pair sample were excluded from the group analyses because of missing parent ratings of clinical impairment. Therefore, their current ADHD status could not be determined. Two additional participants from the ADHD−sibling pair sample were excluded because of drowsiness during the cognitive task. Two participants with childhood ADHD, who did not meet ADHD symptom criteria but did meet clinical levels of impairment at follow-up, were excluded to minimize heterogeneity in the ADHD sample. In addition to these exclusions, which are identical to those in our previous analysis,DSM-IV ADHD criteria based on the parent-rated Barkley Informant Rating Scale.Six control participants were removed from the analyses for meeting DSM-IV criteria for both adult and childhood ADHD symptoms and impairment. It consists of 18 items used to define the DSM-IV symptom criteria for ADHD. Each item is scored affirmatively if the behavioral symptom was present often within the past 6 months.The Diagnostic Interview for ADHD in Adults (DIVA)DSM-IV symptoms subscales forms a total DSM-IV ADHD symptoms subscale.Inattentive and hyperactive-impulsive symptoms were measured using the Long Version of Conners’ Parent Rating Scale.The Barkley Functional Impairment Scale (BFIS)In the preterm and ADHD groups, ADHD was assessed using parental ADHD symptom ratings on the DIVA and the BFIS for all participants, for consistency. If participants were usually on stimulant medication, parents were instructed to consider their children’s ADHD symptoms off medication. A research diagnosis of ADHD was made if participants scored six or more on either the inattention or hyperactivity-impulsivity subscales of the DIVA and if they received two or more positive scores on two or more areas of impairment on the BFIS. In the control group, ADHD was assessed using parental ADHD symptom ratings on the BFIS for all participants, for consistency. Control participants were excluded from the analysis if they received two or more positive scores on two or more areas of impairment on the BFIS.The vocabulary and block design subtests of the Wechsler Abbreviated Scale of Intelligence− Fourth Edition (WASI-IV)The CPT-OX is a cued Go/NoGo task that probes attention, preparation, and response inhibition. The task consisted of 400 black letter arrays made up of a center letter and incompatible flankers on each side to increase difficulty. The presented arrays included the cue letter O, the target letter X, as well as the distractors H, B, C, D, E, F, G, J, and L. Cue and target letters (O and X respectively) were flanked by incompatible letters (XOX and OXO respectively). Participants were instructed to ignore the flanking letters and respond as quickly as possible to cue-target sequences (O-X). A total of 80 cues (XOX) were followed by the target (OXO) in 40 trials (Go condition), and by neutral distractors in the remainder of trials (NoGo condition). In 40 trials, the target letter X was not preceded by a cue O and had to be ignored. Letters were presented every 1.65 seconds for 150 milliseconds in a pseudo-randomized order. Ten practice trials preceded the main task and were repeated, if required, to ensure participant comprehension. Participants were instructed to respond only to Cue-Go sequences by pressing a button as quickly as possible with the index finger of their preferred hand. Participants were further asked to withhold the response in the presence of a NoGo stimulus, in the presence of a Go stimulus not preceded by a cue, or in the presence of any other irrelevant letters. Task duration was 11 minutes.Cognitive-performance measures obtained from the CPT-OX include MRT (mean latency of response after target onset in milliseconds), RTV (standard deviation of target reaction time), and number of errors. MRT and RTV were obtained from correct Go trials. Errors included total omission errors  and total commission errors .Participants attended a single 4.5-hour research session, which included an EEG assessment, an IQ test, and clinical interviews. As part of the EEG assessment, participants completed a CPT with flankers (CPT-OX).The EEG was recorded from a 62-channel direct-current coupled (DCC) recording system (extended 10–20 montage), using a 500-Hz sampling-rate, impedances less than 10 kΩ, and FCz as the recording reference. The electro-oculograms were recorded from electrodes above and below the left eye and at the outer canthi. The EEG data were analyzed using Brain Vision Analyzer 2.0 . Raw EEG recordings were down-sampled to 256 Hz, re-referenced to the average of all electrodes, and digitally filtered using Butterworth band-pass filters . All trials were also visually inspected for electrical artifacts or obvious movement, and sections of data containing artifacts were removed manually. Ocular artefacts, corresponding to blink-related, vertical and horizontal eye movements, were identified using the infomax Independent Component Analysis (ICA) algorithm,For the CPT, stimulus-locked epochs  were averaged based on three different response conditions: Cue, Go, and NoGo. Averages were calculated for trials with correct responses (Go) or correctly rejected trials (NoGo and Cue), which included at least 20 artifact-free segments  were excluded from the ERP analysis of the Go condition, 16 preterm-born participants (8.6%) were excluded from the ERP analysis of the NoGo condition, and four preterm-born participants (2.2%) were excluded from the ERP analysis of the Cue condition due to having fewer than 20 artifact-free segments available for analysis. Seven participants with ADHD (10.1%) were excluded from the ERP analysis of the Go and NoGo condition, and two participants with ADHD (2.9%) were excluded from the ERP analysis of the Cue condition due to having fewer than 20 artifact-free segments available for analysis. Two control participants (1.5%) were excluded from the ERP analysis of the Go condition, and six control participants (4.4%) were excluded from the ERP analysis of the NoGo condition due to having fewer than 20 artifact-free segments available for analysis.d), which were calculated using the difference in the means divided by the pooled standard deviation,d = 0.20 constitutes a small effect, d = 0.50 a medium effect, and d = 0.80 a large effect.Data were analyzed using random intercept models in Stata to control for nonindependence of the data , using a “robust cluster” command to estimate standard errors.z = 1.21, p = .225), RTV , the number of total OE , and the number of total CE  , demonstrating significantly lower RTV scores in the ADHD group compared to the control group.No significant main effects of group emerged for MRT ( = .785) . Becausez = 0.40, p = .687), RTV , or the numbers of total omission  and commission errors  when IQ was included as a covariate. DIVA ADHD symptom scores in the preterm group were significantly correlated with MRT , RTV , OE , and CE  when IQ was included as a covariate.No significant main effect of group emerged for MRT . Because our previous analysis of the ADHD and control groups showed case−control differences on Cue-P3 amplitude, we repeated the analysis without the preterm group to check whether we could repeat our previous findings. We suspected that the lack of ADHD−control differences was due to a large preterm group lying intermediate between the ADHD and control groups. The random intercept model yielded a significant main effect of group for Cue-P3 amplitude , demonstrating significantly reduced Cue-P3 amplitude in the ADHD group compared to the control group. DIVA ADHD symptom scores in the preterm group were not significantly correlated with Cue-P3 amplitude .No significant main effect of group emerged for Cue-P3 amplitude  and a significant group-by-recording site interaction   was found. Post hoc tests revealed that the control group demonstrated significantly greater CNV amplitude at Cz compared to both the ADHD  and preterm groups  with small-to-moderate effect sizes (d = 0.44 and d = 0.38 respectively) . Further post hoc tests revealed that the control group demonstrated significantly greater CNV amplitude at CPz compared to both the ADHD  and preterm groups , with moderate effect sizes (d = 0.60 and d = 0.63 respectively) . DIVA ADHD symptom scores in the preterm group were not significantly correlated with CNV amplitude .The random intercept model yielded a significant main effect of group for CNV amplitude ( = .027) . No signctively) . The ADHctively) . The ADHz = −1.04, p = .299) when IQ was included as a covariate. The random intercept model yielded a significant main effect of group for CNV amplitude  and a significant group-by-recording site interaction  when IQ was included as a covariate. No significant main effect of recording site (Cz and CPz)  was found when IQ was included as a covariate. Post hoc tests revealed that the control group demonstrated significantly greater CNV amplitude at Cz compared to the preterm group  but not compared to the ADHD group . The ADHD and preterm groups did not differ significantly with regard to CNV amplitude at Cz . Further post hoc tests revealed that the control group demonstrated significantly greater CNV amplitude at CPz compared to both the preterm  and ADHD  groups. The ADHD and preterm groups did not differ significantly with regard to CNV amplitude at CPz .No significant main effect of group emerged for Cue-P3 amplitude   and no group-by-recording site interaction  were found. Post hoc tests revealed that Go-P3 amplitude in the ADHD group was not significantly different from Go-P3 amplitude in the control  and preterm groups . The preterm group demonstrated significantly attenuated Go-P3 amplitude compared to the control group , with a small effect size (d = 0.36) .The random intercept model yielded a significant main effect of group for Go-P3 amplitude ( = .004) . No sign = 0.36) . DIVA ADz = −2.80, p = .005) when IQ was included as a covariate. No significant main effect of recording site (CPz and Pz)  and no group-by-site interaction  was found when IQ was included as a covariate. Post hoc tests revealed that Go-P3 amplitude in the ADHD group was not significantly different from Go-P3 amplitude in the control  and preterm groups  when IQ was included as a covariate. The preterm group demonstrated significantly attenuated Go-P3 amplitude compared to the control group  when IQ was included as a covariate.The random intercept model yielded a significant main effect of group for Go-P3 amplitude . NoGo-N2 amplitude was not previously investigated in this sample of adolescents with ADHD and controls.z = −1.01, p = .313) and recording site (FCz and Cz)  emerged . Post hoc tests revealed that the ADHD group showed significantly attenuated NoGo-P3 amplitude at FCz compared to the preterm group , with small effect size (d = 0.37), but not compared to the control group . No significant difference in NoGo-P3 amplitude at FCz emerged between preterm and control participants . Although the ADHD and preterm groups demonstrated no significant difference in NoGo-P3 amplitude at Cz , both the ADHD  and preterm  groups showed significantly attenuated NoGo-P3 amplitude at Cz compared to the control group, with moderate effect sizes (d = 0.63 and d = 0.54). DIVA ADHD symptom scores in the preterm group were significantly negatively correlated with NoGo-P3 amplitude .The random intercept model yielded no significant main effect of group for NoGo-N2 amplitude  when IQ was included as a covariate. For NoGo-P3 amplitude, no significant main effect of group  and recording site (FCz and Cz)  emerged when IQ was included as a covariate. However, a significant group-by-recording site interaction emerged for NoGo-P3 amplitude  when IQ was included as a covariate. Post hoc tests revealed that the ADHD group showed significantly attenuated NoGo-P3 amplitude at FCz compared to the preterm group , but not compared to the control group . No significant difference in NoGo-P3 amplitude at FCz emerged between preterm and control participants . Although the ADHD and preterm groups demonstrated no significant difference in NoGo-P3 amplitude at Cz , both the ADHD  and preterm groups  showed significantly attenuated NoGo-P3 amplitude at Cz compared to the control group when IQ was included as a covariate.The random intercept model yielded no significant main effect of group for NoGo-N2 amplitude , response preparation (CNV), and response inhibition (NoGo-P3) impairments in preterm-born individuals. Although the observed impairment in executive response control (Go-P3) represents preterm birth-specific impairments, response preparation (CNV) and response inhibition (NoGo-P3) impairments were also observed in individuals with ADHD.Our ERP results show a significant group difference in P3 amplitude in response to Go stimuli, which was reduced in preterm-born adolescents compared to the control group. The Go-P3 has been linked to several attentional functions, such as evaluation of stimuli and resource allocation,57Response inhibition impairments, as indexed by abnormal NoGo-P3 amplitude, were observed in the preterm-born adolescents. These impairments were linked to the increased ADHD symptoms in the preterm group. Our previous research had also established response inhibition impairments, reflected by decreased NoGo-P3 amplitude, in adolescents with ADHD.We further identified the same CNV abnormalities in the preterm group as observed in individuals with ADHD,No significant differences in mean reaction time (MRT), reaction time variability (RTV), omission errors (OE), and commission errors (CE) were found between the preterm and control groups, suggesting that preterm-born adolescents may be able to compensate for the impairment seen in the brain processes involved in response preparation, executive response control, and response inhibition. As reported previously, the ADHD group demonstrated significantly increased MRT and RTV and a greater number of OEs compared to both preterm and control groups,66DSM criteria for ADHD closely. It inquires about the presence of ADHD symptoms in adulthood as well as in childhood, and about the chronicity of these symptoms, and it can therefore be easily adapted for use in younger participants. Nonetheless, future studies should apply diagnostic measures normed for their population.A limitation of this study is that we were unable to investigate whether risk factors for being preterm  might account for the ERP findings in our sample. Although population-based quasi-experimental designs have established that the associations between preterm birth and psychiatric morbidity are largely independent of shared familial confounds and measured covariates, consistent with a causal inference,In conclusion, this study provides evidence for impairments in brain processes involved in response preparation, executive response control, and response inhibition in adolescents born preterm. Although some of the impairments found in adolescents born preterm overlap with those found in term-born adolescents with ADHD, the preterm group also shows unique impairments, indicating more wide-ranging impairments in the preterm group, compared to individuals with ADHD. This idea is supported by research suggesting that, as well as being a risk factor for ADHD, preterm birth presents a risk factor for other psychiatric disorders, such as schizophrenia, bipolar disorder, and autism spectrum disorder.


The prevalence of low birth weight (LBW) and neurobehavioral disorders (N) has increased over the last three decades. However, it is unclear how many excess cases of ND can be attributed to LBW among U.S. children. The objectives of this study were to a) determine the association between LBW and ND including attention deficit/hyperactivity disorder (ADHD), autism spectrum disorder (ASD), behavior and conduct disorder (BCD) and learning disability (LD); and b) determine the population attributable risk (PAR) of these disorders due to LBW.Study subjects were a nationally representative cross-sectional sample of 85,637 children ages 2 to 17 years old who participated in the 2011 National Survey of Children’s Health. Birth weight and ND were reported by parents.LBW accounted for 6.0%  of all ASD cases, 2.4% (CI 0.1–5.1) of BCD, and 6.8% (CI 4.8–9.0) of LD among the study population. There was not a significant association between LBW and ADHD. The percentages of these ND due to LBW were found to be higher among those who were pre-term and among ethnic minority groups.Based on our results and given that over 8% of U.S. children are born with LBW, with higher rates among minorities and preterm births, prospective planning for neurobehavioral services is warranted. Efforts to reduce ND in children align with national efforts to reduce LBW. Rates of low birth weight  have been increasing since the mid 1980s in the United States . NumerouLike LBW, neurobehavioral (ND) and neurodevelopmental disorders, such as attention deficit disorder (ADD)/attention deficit and hyperactivity disorder (ADHD) and autism spectrum disorders (ASD) have also increased during the past several decades , 9. UsinIn this study, we used data from the 2011 National Survey of Children’s Health (NSCH) to examine this association. Specifically, the purpose of this study was to determine the strength of association between parent-reported LBW and ND in a nationally representative sample of children after adjustment for potential confounders. We then estimated the population-attributable risks and excess cases of these disorders due to LBW. The findings of this study provide information on the potential LBW-associated disease burden in the U.S. population and are useful for health and education program planning.Data for this study come from the 2011 NSCH, which was funded by the Maternal and Child Health Bureau of the Health Resources and Services Administration, and conducted by the Centers for Disease Control and Prevention, National Center for Health Statistics. The purpose of the NSCH is to provide national and state-specific prevalence rates of various health conditions and to assess the health and well-being of U.S. children in broad domains including medical care, housing, family interactions, parental health, school and after-school activities, safe neighborhoods and social connectedness. The 2011 NSCH was a random-digit-dial phone survey conducted between February 2011 and June 2012. One child was randomly selected per household. The respondent was identified by the interviewer as the parent or guardian most knowledgeable about the selected child’s health. The total sample size consisted of 95,677 children ages 0 through 17. The sample was stratified by state so that each state had approximately 1,800 children participating in the survey.For the purposes of this study, children 2 through 17 years old were selected because neurobehavioral questions were asked only amongst this age group, and are most functionally relevant to this age group. As a result of these exclusions, this analysis included 85,637 children ages 2 through 17 years old.The main predictor variable of interest was parent-reported LBW. Birth weight was assessed through the question, “What was [sampling child’s] birth weight?” Children born at a birth weight less than 2,500 grams (5.5 pounds) were classified as LBW. Children with birth weight of 2,500 grams (5.5 pounds) or greater were classified as normal birth weight (NBW). The main outcomes of interest were parent-reported ND, which included ADHD, ASD, behavioral or conduct disorders (BCD), and learning disability (LD). The outcomes were assessed using the telephone survey responses. A child is defined as a case if his/her parent answered “yes” to the outcome-specific questions below:ADHD: “Has a doctor or other health care provider ever told you that [sampling child] had attention deficit disorder or attention deficit hyperactive disorder, that is, ADD or ADHD?”ASD: “Has a doctor or other health care provider ever told you that [sampling child] had autism, Asperger’s syndrome, pervasive developmental disorder, or other autism spectrum disorder?”BCD: “Has a doctor or other health care provider ever told you that [sampling child] had behavioral or conduct problems, such as oppositional defiant disorder or conduct disorder?”LD: “Has a doctor, health care provider, teacher, or school official ever told you [sampling child] had a learning disability?”Covariates considered in the study included age group , gender , ethnicity , place of residence , family structure , insurance status (yes or no), exposure to environmental smoking (yes or no), maternal education , primary language (English or other), poverty level , 100%–200% FPL, or more than 200% FPL), exposure to neighborhood violence (yes or no), presence of someone with mental illness in household (yes or no), presence of someone with alcohol/drug problems in the household (yes or no), prematurity status (yes or no).The 2011 NSCH employed a complex sampling design that involved unequal selection probability of children within households and households within states. Therefore, all analyses were performed with adjustment for sample weight to account for sampling design, potential non-coverage (for those who did not have a home phone line) and non-response bias. All analyses were performed using SAS 9.3 .Chi-square tests were used to describe and compare the distribution of weighted prevalence of LBW measures among children with ascertained demographic characteristics . In addition, the weighted prevalence of ND among children by demographic characteristics was also tested. Three logistic regression models were fitted, using PROC SURVEYLOGISTIC, to estimate the unadjusted and adjusted odds ratio (OR) and 95% confidence intervals (CI) for having ND, comparing children with various LBW measures to those of normal birth weight (NBW). The first model [model 1] fitted the unadjusted OR for neurobehavioral disorders. The second model model 2] was a parsimonious model, which adjusted for potential confounders that are found to be associated with both LBW measures and neurobehavioral outcomes in  was a paPopulation-attributable risk percentage (PAR%) was estimated for each of the parent-reported neurobehavioral disorders using Levine’s formula: PAR%=([(Pexp(OR−1)]/[ Pexp(OR−1)+1])× 100, where Pexp is the prevalence of exposure to LBW, and OR is the unadjusted OR for each disorder , 15. We There were a total of 85,637 children, ages 2 through 17 years old in the 2011 NSCH survey. Among them, 4,530 had missing birth weight, leaving 81,107 available for analysis. Of these, 9.5% (SE: 0.23) were born with a LBW as reported by their parent, corresponding to 5.88 million children living in 2011 who were born with LBW in previous years (data not shown). The weighted prevalence of parent-reported ND among children ages 2 to 17 was approximately 9.9% for ADHD, 2.3% for ASD, 4.1% for BCD, and 10.6% for LD (for ages 3 through 17 years-old since this question was only asked amongst children in this age group). Among children 3 to 17 years-old, 10.5% had only 1 of the 4 ND, and 8.2% had 2 or more co-occurring disorders. When compared to NBW children, the prevalence for all ND was significantly higher among LBW children . The preThe ORs of the associations between parent-reported LBW and ND among U.S. children ages 2 through 17 years old are shown in In order to obtain more refined birth weight exposure, we also investigated the risk for other LBW categories: moderately LBW  and very LBW . Overall, the results remained consistent with VLBW having stronger associations with all disorders (data not shown). We further investigated the effects of LBW on co-occurrence of ND. Our results showed that children with LBW also have significantly higher odds of having two or more co-occurring disorders after adjustment for confounders  . Effect We also stratified results by ethnicity and prematurity status (born 3 weeks prior to the due date as reported by parents) due to difference in prevalence of parent-reported LBW. Among non-Hispanic whites, the percent of total cases attributed to LBW in the population was 5.3 (95% CI: 3.8–7.1) for LD, 4.6(95% CI:1.8–8.2) for ASD, and 1.9 (95% CI:0.1–4.0) for BCD. These percentages correspond to 180,967 excess cases of LD, 41,500 cases of ASD and 25,348 excess cases of BCD in 2011. For these same disorders, the PAR% was higher among non-Hispanic black, Hispanic and other ethnicity groups compared to non-Hispanic whites. However, the number of excess cases was lower for these minorities groups because the population is smaller and thus the total number of cases was lower .Among pre-term births, the percent of total cases associated with LBW was significantly higher compared to full-term births . For thiThis study found evidence that in 2011, U.S. children ages 2 through 17 years-old who were born having LBW were significantly more likely to have ASD, BCD and LD, but not ADHD, as reported by their parents. In effect, LBW was likely responsible for a considerable number of excess cases of ND reported during the study period. There was also a clear racial disparity in terms of the extent of effects that LBW has on ND. In particular, the proportions of each disorder attributed to LBW among non-Hispanic black, Hispanic, and other race/ethnicity groups were considerably higher than among non-Hispanic whites. Our findings further illustrate that the proportions of each disorder attributed to LBW among preterm births were significantly higher compared to full-term births.The associations between parent-reported LBW and ND found in this study were consistent with previous studies that investigated effects of various LBW indicators on various neurobehavioral health outcomes , 16, 17.On the other hand, the lack of significant association between LBW and ADHD in our study is inconsistent with the literature , 19. ForWe stratified our analysis of PAR% by race and prematurity status because historically the prevalence of LBW has been consistently different for these groups. These analyses help address the question whether the higher prevalence of ND among ethnic minority groups and premature births can be explained by the higher proportion of LBW. It appears that LBW has the strongest effects among ethnic minorities because although the number of excess cases is lower among them , their attributable risks are higher compared to non-Hispanic whites for every disorder. Further analyses also showed very high numbers of excess cases for each ND, in particular LD and ASD. These findings suggest that if LBW can be reduced, fewer ND would be diagnosed in US children ages 2 through 17 years-old. More importantly, the higher PAR among minorities suggests that if LBW could be reduced in these groups in which it is more prevalent, the gap in pediatric neurobehavioral outcomes between non-Hispanic white and other ethnic groups would decrease.The higher PAR% of parent-reported ND due to LBW among preterm births also suggest that a higher proportion of cases among this group is possibly due to LBW. This finding also implies that if preterm births can be reduced, there would be fewer excess cases of ND. While there are myriad factors that influence LBW that cannot be controlled, one potential means of decreasing preterm births is to reduce the rates of elective induction of labor. Given the prevalence of elective labor induction prior to due date in the United States , 24, it Maternal malnutrition and placental insufficiencies are two known factors that influence LBW . While mThis study has several strengths. First, the sample is generally applicable to U.S. children because it utilizes data from a nationally representative sample of children from ages 2–17. Second, the study is the first to assess PAR% and excess cases of ND due to LBW. However, the study also has several limitations. First, both exposure and outcome are based on parental reporting, and thus the information may not represent actual diagnoses. Consequently, misclassification bias may have occurred. For example, our analysis showed a higher LBW prevalence compared to the national U.S. average of 8.1% during 2011 . This hiSecondly, since this study relied on available data, we were unable to adjust for all possible confounders. For example, maternal age at delivery, gestational age, and pregnancy complications could be important confounders; however, this information was not available for analysis. The lack of information about these covariates prevented us from examining other potential reasons for LBW, such as congenital anomalies or genetic disorders, that also lead to neurobehavioral deficits and disorders.Although this is a cross-sectional study, temporality can be assumed because it is not logical to claim NBD precede LBW. We also acknowledge the limitation of using OR as an estimate of risk. When used in Levine’s formula, OR may have overestimated the attributable risk. However, given the low prevalence of ND, overestimation is not likely to be a serious concern.The study showed that parent-reported LBW is a major contributor to parent-reported pediatric ND including LD, ASD and BCD. Decreasing the occurrence of LBW births could potentially reduce the number of ND in children between the ages of 2 and 17 in the U.S. However, since there is currently no effective population-level LBW prevention strategy, prospectively planning for neurobehavioral services is merited. Early referral would be particularly helpful for racial minority groups because the prevalence of LBW is higher in these groups compared to the white population. The findings of our study also suggest that efforts to prevent neurodevelopment disorders in children need to start prior to conception and be maintained throughout pregnancy to assure that the infant is born at full-term.


Clinical heterogeneity is a well-established characteristic of autism spectrum disorder (ASD). While the comorbidity of ASD and ADHD is well known in clinical practice, relatively little research has examined the neuropsychological profile of children with ASD + ADHD. Our study showed significant differences in the neuropsychological characteristics of children with ASD + ADHD compared to those with ASD only. Children with ASD + ADHD showed higher symptoms of anxiety, worse working memory, and less empathy, as measured by the “Reading the Mind in the Eyes.” This suggests that having ADHD brings further challenges to individuals with ASD and may negatively impact their management and outcome. Our findings may have implications for clinical assessment as well as for intervention. Clinical heterogeneity is a well-established characteristic of autism spectrum disorder (ASD). In addition to the core features of social communication impairment and restricted/repetitive behaviors and interests, a large number of children with ASD present with the symptoms of hyperactivity, inattention, and impulsivity, which may be severe enough to merit an additional diagnosis of attention deficit hyperactivity disorder (ADHD) . AlthougIt is crucial to identify the comorbidity between ASD and ADHD because of its treatment implications. For example, compared with children with ADHD only, those with ADHD and ASD symptoms have a lower adaptive functioning and a poorer quality of life , 11. In However, despite the group differences reported in the literature, it can be extremely difficult to differentiate between ASD and ADHD in individual cases. Historical data and presentation of symptoms may not be helpful. For example, social deficits occur in both the disorders. Although the social deficits of autism are typically described as being “reciprocal” in nature resulting from an inborn lack of “affective contact”  and thosIn such cases, a careful evaluation of the neuropsychological characteristics may be helpful in identifying the comorbidity of ASD and ADHD. Cognitive profiles of individuals with ASD and those with ADHD are well described. For example, in a rigorous study of high functioning individuals with ASD, Wilson et al.  found thLimited research has been done on the neuropsychological characteristics of individuals with ASD + ADHD. Some authors have suggested that those with ASD + ADHD show an “additive profile” rather than a qualitatively different set of difficulties compared with those with ASD only . For example, Andersen et al.  found thThe study was conducted at the Department of Psychiatry, University of Michigan, and approved by the Institutional Review Board (HUM00008815). The participants, drawn from referrals to the ASD Clinic, consisted of 22 children with ASD and 25 children with mixed ASD and ADHD. The demographics are presented in The diagnosis of ASD, based on the DSM-IV , was reaNeuropsychological measures were administrated using standardized procedures. Measures, based on the main ASD deficits identified in the scientific literature, evaluated cognitive level of functioning, emotion recognition, Theory of Mind, executive functions, and motor abilities. The following measures were administered.The Wechsler Intelligence Scale for Children, 4th Edition (WISC IV). It includes 10 subtests, yielding four index scores that combine into the Full Scale IQ (FSIQ). The Verbal Comprehension Index (VCI) consists of three subtests . The Perceptual Reasoning Index (PRI) comprises Block Design, Matrix Reasoning, and Picture Concepts. The Working Memory Index (WMI) comprises Digit Span and Letter-Number Sequencing. The Processing Speed Index (PSI) comprises Coding and Symbol Search. Index standard scores have a mean of 100 and a standard deviation of 15.Trail Making Test. The Trail Making Test (TMT) [st (TMT)  is a visTower of London. The Tower of London  measures planning and problem solving performance. The mechanical version of the TOL used in this study consists of two identical wooden game boards, one for the participants and one for the examiner. Each game board includes three different size pegs and three different colored balls. The participant needs to move the balls on the pegs to match the examiner's game board in the minimum number of moves.The Strange Stories Task . It consists of vignettes depicting social situations. The task requires the participant to explain a character's behavior with reference to his or her mental states. This is a measure of Theory of Mind.Reading the Mind in the Eyes, Revised Version . The revised version of the Eyes Test [yes Test  consistsThe Child Behavior Checklist (CBCL) . It is a measure assessing disruptive behavior and social competency in children. Caregivers of the participants completed the Child Behavior Checklist (CBCL). We used the CBCL to confirm ADHD symptoms.t-tests comparing the two groups in terms of age and IQ. We then performed univariate analyses of covariance (ANCOVAs), comparing the two groups while including IQ as a continuous covariate, for the following dependent variables: working memory, Children's Color Trail Test, Tower of London, Category Fluency Test, Happe's Stories, and Reading the Mind in the Eyes Test.Statistical analyses were performed using the IBM SPSS Statistics software (Version 23). We first performed independent samples t-tests showed that the two groups did not differ in terms of mean age, mean Full Scale IQ, mean Verbal IQ, and mean Performance IQ. ADHD symptoms  and anxiety symptoms , as measured by the CBCL, were higher in the group of children with ASD + ADHD compared with the ASD only group. Based on the results of the ANCOVAs, there was a significant difference between the two groups in working memory  = 4.52; p = 0.041), with the ASD only group having a significantly higher mean when holding FIQ fixed, indicating that children with ASD + ADHD present more impairment in working memory. Additionally, there was a marginally significant difference in the Reading the Mind in the Eyes Test  = 3.44, p = 0.07), with the ASD only group having a marginally higher mean when controlling for FIQ, indicating that the ASD + ADHD group present slightly higher difficulties in the Eyes Test. The Trail Making Test, Tower of London, Category Fluency Test, and Happe's Stories did not show significant differences between the groups.Descriptive statistics for the two groups are reported in In 1902, about 50 years before Leo Kanner described autism, George Still laid down the main characteristics of the condition that later came to be known as ADHD . While Kanner did not describe the comorbid disorders his eleven patients suffered from, a close reading of his seminal paper suggests that at least a few of them seemed to show symptoms that would today be diagnosed as ADHD. Before the DSM-5  was publThe main finding of this study is that compared with children who have ASD only those who have ASD + ADHD are more impaired in their ability to read other people's emotions and feelings (“Reading the Mind in the Eyes Test”) and to hold and manipulate critical periods of information (“working memory”). Thus, when we compared the neuropsychological profiles of 22 children with ASD only with those of 25 children with ASD + ADHD, we found significant differences between the two groups. Working memory was significantly more impaired in children with additional ADHD. Moreover, a marginally significant difference was identified in the Eyes Test, indicating that children with ASD + ADHD may have more difficulties in emotion recognition. Regarding behavioral symptoms, children with ASD + ADHD showed higher levels of anxiety in line with other studies , 20; howIt is to be noted that the sample consisted only of those with normal level of intelligence. Therefore, the findings may not apply to lower functioning children with ASD and ADHD. The risk of intellectual disability (ID) increases the risk of both ASD and ADHD, acting alone and in combination with other factors. Indeed, diagnosing the two conditions in those with severe and profound intellectual disability is extremely difficult. Since working memory is impaired in those with ID , it can In summary, identifying symptoms of ADHD in children with ASD has important diagnostic and treatment implications. However, a reliable diagnosis based only on developmental history and clinical observation is not always possible. Examining the cognitive and neuropsychological deficits in children with both the conditions can facilitate their diagnosis and inform treatment. Our results also confirm the greater overall impairment in children with ASD plus ADHD as indexed by their performance on tests of social cognition. Further studies in subjects with a wider range of cognitive abilities, using larger sample sizes of different age groups, should be undertaken to better define the profiles of individuals with ASD + ADHD and identify effective pharmacological and behavioral interventions.