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Objective: The Quantified Behavioral Test (QbTest) is a computerized diagnostic test for ADHD, used in clinical psychiatric care, but its validity may be questioned. We analyzed the QbTest's diagnostic validity and its relation to cognitive ability and psychosocial factors in an adolescent population with a high occurrence of neurodevelopmental disorders. Method: In total, 340 participants aged 15 years, completed the QbTest, along with questionnaires, clinical and intelligence quotient (IQ) assessments. Results: The clinical assessment resulted in 89 (26%) participants with ADHD. Area under curve (AUC) scores indicated a random to poor validity of the QbTest (AUC range = 0.48-0.64). QbTest scores of inattention and impulsivity correlated with IQ. Conclusion: The QbTest was insufficient as a diagnostic test for ADHD, and was not able to differentiate ADHD from other neurodevelopmental conditions. Clinicians should be aware of the dubious discriminating power of the QbTest.

Previous studies have shown an association between IQ and adaptive global functioning, i.e. how well a person is functioning in different domains of life. However, it is unclear to what extent such an association applies in children with neurodevelopmental disorders (NDDs). The study group consisted of 550 population-screened children assessed with the K-SADS, WISC-IV, and the C-GAS. Approximately half of the sample had been diagnosed with one or several NDDs (ADHD, autism, language disorder and tic disorder). A factorial ANOVA with IQ level and the presence of NDD was conducted, with C-GAS score as the dependent variable. Results revealed a significant interaction effect between IQ-group and NDD-status. In the non-NDD group (49% girls), higher IQ scores were clearly linked with better global adaptive functioning. Among children with NDDs (35% girls), however, higher IQ scores were not clearly associated with better functioning. Thus, the association between IQ and adaptive functioning were found to differ depending on the presence of NDD. These results have implications for the interpretation of IQ test results in neurodevelopmental assessments and point towards the importance of providing support based on an assessment of needs and functioning rather than scores from IQ tests.

Det svenska rättssystemet som tillåter att vi dömer psykiskt sjuka för brott och att personer som saknar vårdbehov kan hållas frihetsberövade inom rättspsykiatrin under mycket lång tid med oklart vårdinnehåll, är unikt och har fått rättmätig kritik under lång tid. Ändå händer ingenting.

BACKGROUND: We examined whether childhood conduct problems predicted a wide range of adverse outcomes in emerging adulthood and whether the association with internalizing problems remained after adjusting for general comorbidity and externalizing problems. METHODS: Participants were 18,649 twins from the Child and Adolescent Twin Study in Sweden. At age 9/12, parents rated their children on eight conduct problems. Adverse outcomes were retrieved from national registers in emerging adulthood (median follow-up time = 9.2 years), including diagnoses of six psychiatric disorders, prescriptions of antidepressants, suicide attempts, criminality, high school ineligibility, and social welfare recipiency. We estimated risk for the separate outcomes and examined if conduct problems predicted an internalizing factor above and beyond a general comorbidity and an externalizing factor. We used twin analyses to estimate genetic and environmental contributions to these associations. RESULTS: On the average, each additional conduct symptom in childhood was associated with a 32% increased risk of the adverse outcomes in emerging adulthood (mean hazard ratio = 1.32; range = 1.16, 1.56). A latent childhood conduct problems factor predicted the internalizing factor in emerging adulthood (beta(boys) = .24, standard error, SE = 0.03; beta(girls) = .17, SE = 0.03), above and beyond its association with the externalizing (beta(boys) = 0.21, SE = 0.04; beta(girls) = 0.17, SE = 0.05) and general factors (beta(boys) = 0.45, SE = 0.03; beta(girls) = 0.34, SE = 0.04). These associations were differentially influenced by genetic and environmental factors. CONCLUSIONS: It is important to monitor boys and girls with conduct problems not only for future externalizing problems, but also for future internalizing problems. Prevention of specific outcomes, however, might require interventions at different levels.

The original version of this article unfortunately contained a mistake in Fig. 2 part labels, the label "d" was incorrectly labelled as "c" and the subsequent labels should be corrected as d, e, and f. The corrected Fig. 2 is given below., Erratum for Physical health in children with neurodevelopmental disorders. [J Autism Dev Disord. 2018]The original article has been corrected.

With increasing numbers of children being diagnosed with neurodevelopmental disorders (NDDs) attention has been drawn to these children's physical health. We aimed to identify the prevalence of defined physical problems (epilepsy, migraine, asthma, cancer, diabetes, psoriasis, lactose intolerance, celiac disease, diarrhea, constipation, daytime enuresis, encopresis) in a nationwide population of 9- and 12-year-old twins subdivided into those with and without indications of NDDs. Parents of 28,058 twins participated in a well-validated telephone interview regarding their children's mental health and answered questions about their physical problems. The results indicate a high rate of physical problems in children with NDDs, particularly in those with indications of the presence of combinations of several NDDs.

There is a need for instruments that can be used in correctional settings to measure changes in aggressive behaviors over a limited time period. This study aimed to validate an instrument (the Prison Adjusted Measure of Aggression, PAMA) that assesses specifically the past month’s aggressive behaviors and is adapted for use in correctional facilities. The psychometric properties of the self-rated and interview versions of the PAMA were explored and compared to those of two well-established measures of aggression: The Staff Observation Aggression Scale (SOAS); and the self-rate Aggression Questionnaire-Revised Swedish Version (AQ-RSV). The study group comprised 93 male and 59 female inmates, who were followed for two months. During the study, the prevalence of aggressive acts was observed and reported by SOAS. On two occasions, at monthly intervals, subjects reported their own aggressive behaviors using AQ-RSV and the self-report version of the PAMA; also, a psychologist conducted interviews according to PAMA. This study’s main finding was that the self-rated version of PAMA is a valid measure of different types and dimensions of aggression (physical and verbal aggression, hostility) and has acceptable psychometric properties. Therefore, PAMA could potentially be of value for use in correctional services evaluating aggression managing treatment interventions., Available online 1 March 2018

Previous research has found a complex relationship between psychopathic traits, neurodevelopmental problems (NDPs), and conduct disorder (CD) in children. This study explores associations between psychopathic traits, assessed with the Child Problematic Traits Inventory—Short Version (CPTI-SV), and CD in children with and without coexisting NDPs (i.e., attention deficit/hyperactivity disorder [ADHD] and autism spectrum disorder [ASD]) in a community-based sample of Swedish twins (n = 8762). Findings indicate weak to moderately strong correlations between psychopathic traits and CD, ADHD, and ASD, respectively. Furthermore, in univariable analyses, both psychopathic traits and NDPs displayed significant positive associations with being screened positive for CD, though only the grandiose-deceitful dimension of CPTI-SV and the ADHD domain concentration and attention deficits remained significantly associated with CD in a multivariable regression model. The results are relevant to screening and assessment in child and youth psychiatry, as a grandiose and deceitful interpersonal style may also be a valid sign of children at risk of developing CD., First Online: 29 June 2018Funders: Söderström-Königska Foundation; the European Union Seventh Framework Programme (FP7/2007–2013, no. 602768

BACKGROUND: Childhood aggressive antisocial behavior (CD) is one of the strongest predictors of mental health problems and criminal behavior in adulthood. The aims of this study were to describe personality profiles in children with CD, and to determine the strength of association between defined neurodevelopmental symptoms, dimensions of character maturity and CD. METHODS: A sample of 1886 children with a close to equal distribution of age (9 or 12) and gender, enriched for neurodevelopmental and psychiatric problems were selected from the nationwide Child and Adolescent Twin Study in Sweden. Their parents rated them according to the Junior Temperament and Character Inventory following a telephone interview during which information about the children's development and mental health was assessed with the Autism-Tics, AD/HD and other Comorbidities inventory. RESULT: Scores on the CD module significantly and positively correlated with scores on the Novelty Seeking temperament dimension and negatively with scores on character maturity (Self-Directedness and Cooperativeness). In the group of children with either neurodevelopmental or behavioral problems, the prevalence of low or very low character maturity was 50%, while when these two problems coexisted the prevalence of low or very low character maturity increased to 70%. Neurodevelopmental problems (such as: oppositional defiant disorder, symptoms of attention deficit/hyperactivity disorder and autism spectrum disorder) and low scores on character maturity emerged as independently significant predictors of CD; in a multivariable model, only oppositional defiant symptoms and impulsivity significantly increased the risk for coexisting CD while a mature self-agency in a child (Self-Directedness) remained a significant protective factor. CONCLUSION: These results suggest that children's willpower, the capacity to achieve personally chosen goals may be an important protective factor - even in the presence of neurodevelopm, Available online 29 April 2017

Introduction: Nonrandom selection into a study population due to differences between consenters and non-consenters may introduce participation bias. Past investigations of factors predicting consent to collection of medical health records for research imply that age, sex, health status and education are of importance for participation, but disagree on the direction of effects. Very little is known about influences on consent from adolescents. Methods: Two cohorts of Swedish 15-year-old twins (total n=4,611) previously invited to the Child and Adolescent Twin Study in Sweden (CATSS) responded to a questionnaire with information on gender, individual’s health, height, weight and parental factors. The questionnaire included a question for consent to collection of medical health records. Predictors for consent were analysed using logistic regression. Additionally, regional differences in the collection of health records of consenters were evaluated. Results: Males were significantly less likely to consent compared to females (OR 0.74, 95% CI 0.64-0.85). The twin sibling’s decision to consent was strongly associated with consent (OR 10.9, 95% CI 8.76-13.5), and individuals whose parents had responded to the original CATSS study were more likely to consent to record collection at age 15 (OR 2.2, 95% CI 1.81-2.75). Results of the subsequent collection of consenters’ medical health records varied between geographical regions of Sweden. Conclusion: We identified several predictors for adolescents’ consent to collection of their medical health records. Further selection was introduced through the subsequent record Page 3 of 32 collection. Whether this will induce participation bias in future studies depends on the research questions’ relationship to the identified predictors.

Objective: Attention-deficit/hyperactivity disorder (ADHD) is more common in males than females, yet little is known about why this is the case. We aimed to test for the existence of a ‘female protective effect’ against ADHD traits in two European twin samples. Specifically, we aimed to test whether cotwins of females displaying extreme ADHD traits would display more ADHD traits than co-twins of males displaying extreme ADHD traits. Method: Parents of approximately 7,000 pairs of non-identical twins in Sweden, and around 4,000 pairs of twins in England and Wales, completed dimensional assessments of ADHD traits. Probands were selected on the basis of scoring within the highest 10% of the distribution in each sample. Dimensional scores of co-twins of probands, as well as the categorical recurrence rate, were investigated by proband sex. Results: Co-twins of female probands displayed higher mean ADHD trait scores (mean=0.62-0.79) than co-twins of male probands (mean=0.38-0.55) in both samples. This trend was significant in the Swedish sample (p<.01) and when the two samples were merged into a single, larger sample (p<.001). When the samples were merged, there was also a significant association between proband sex and co-twin’s categorical status, with more co-twins of female probands also being probands than co-twins of male probands. Conclusions: These findings support a female protective effect against ADHD behaviors in the general population, indicating that females require exposure to a greater degree of etiological factors than males to develop ADHD.

Children with attention-deficit/hyperactivity disorder (ADHD) are at increased risk of problematic alcohol and other substance use in adolescence. This study used data from an ongoing, prospective, population-based twin study of Swedish children and adolescents to evaluate the extent to which the association between ADHD symptoms and alcohol problems reflects a unique source of genetic or environmental risk related to ADHD versus a broader predisposition to youth externalizing behavior. We used all available data from same-sex MZ and DZ twins on ADHD symptoms in childhood (age 9/12; N = 15,549) and alcohol problems in late adolescence (age 18; N = 2,564). Consistent with prior longitudinal studies, the phenotypic association between hyperactive/impulsive ADHD symptoms and alcohol problems was small in magnitude, whereas the association for inattentive symptoms was even weaker. Additive genetic influences explained 99.8% of the association between hyperactive/impulsive symptoms and alcohol problems. Furthermore, we found that the genetic risk specifically associated with hyperactive/impulsive symptoms was attenuated when estimated in the context of externalizing behavior liability during childhood, of which ADHD symptoms were specific expressions. In sensitivity analyses exploring hyperactivity in mid-adolescence, we found a similar pattern of genetic associations. These results are consistent with previous findings of genetically driven overlap in the etiology of ADHD and problematic alcohol use. At least some of this cooccurrence may result from a general predisposition to externalizing behaviors in youth.

Gender specific personality profiles in association with the level of aggressive antisocial behavior in offenders have not been previously investigated. In the present study we analyzed data collected from 65 male and 50 female offenders using structured protocols regarding criminal history (by criminal register data), trait aggression (by the Life History of Aggression (LHA) questionnaire), and personality profiles (by the Temperament and Character Inventory (TCI)). Prison inmates differed significantly on several personality dimensions, most pronouncedly were they characterized with low character maturity (low scores in the Self-Directedness and Cooperativeness dimensions of TCI) when compared to gender and age matched controls of the general population. The majority of offenders scored distinctively high on trait aggression. There were moderate to strong associations between the personality dimensions and each of the subscales of LHA (Aggression, Self-directed Aggression and Antisocial behavior). These associations were stronger in the female offender sample. Trait aggression could be best explained by a model, which included male gender, younger age, high novelty seeking temperament and low character maturity. Our results suggest that therapies aiming at strengthening self-governance and increasing cooperativeness (focusing on character maturity) may alleviate aggressive antisocial behavior in offenders., Funders: Kriminalvården, 2011:186

This 3-year follow-up study compares background variables, extent of criminality and criminal recidivism in the form of all court convictions, the use of inpatient care, and number of early deaths in Swedish institutionalized adolescents (N = 100) with comorbid substance use disorders (SUD) and Attention-Deficit/Hyperactivity Disorder (ADHD) (n = 25) versus those with SUD but no ADHD (n = 30), and those without SUD (n = 45). In addition it aims to identify whether potential risk factors related to these groups are associated with persistence in violent criminality. Results showed almost no significant differences between the three diagnostic groups, but the SUD plus ADHD group displayed a somewhat more negative outcome with regard to criminality, and the non-SUD group stood out with very few drug related treatment episodes. However, the rate of criminal recidivism was strikingly high in all three groups, and the use of inpatient care as well as the number of untimely deaths recorded in the study population was dramatically increased compared to a age matched general population group. Finally, age at first conviction emerged as the only significant predictor of persistence in violent criminality with an AUC of .69 (CI (95%) .54–.84, p = .02). Regardless of whether SUD, with or without ADHD, is at hand or not, institutionalized adolescents describe a negative course with extensive criminality and frequent episodes of inpatient treatment, and thus requires a more effective treatment than present youth institutions seem to offer today. However, the few differences found between the three groups, do give some support that those with comorbid SUD and ADHD have the worst prognosis with regard to criminality, health, and untimely death, and as such are in need of even more extensive treatment interventions., Available online 13 October 2016Funders: National Board of Forensic Medicine

Background Restrictive eating problems are rare in children but overrepresented in those with neurodevelopmental problems. Comorbidities decrease wellbeing in affected individuals but research in the area is relatively scarce. This study describes phenotypes, regarding psychiatric and gastrointestinal comorbidities, in children with restrictive eating problems. Methods A parental telephone interview was conducted in 9- or 12-year old twins (n = 19,130) in the Child and Adolescent Twin Study in Sweden. Cases of restrictive eating problems and comorbid problems were established using the Autism, Tics-AD/HD and other Comorbidities inventory, parental reports of comorbidity as well as data from a national patient register. In restrictive eating problem cases, presence of psychiatric and gastrointestinal comorbidity was mapped individually in probands and their co-twin. Two-tailed Mann–Whitney U tests were used to test differences in the mean number of coexisting disorders between boys and girls. Odds ratios were used to compare prevalence figures between individuals with or without restrictive eating problems, and Fisher exact test was used to establish significance. Results Prevalence of restrictive eating problems was 0.6% (concordant in 15% monozygotic and 3% of dizygotic twins). The presence of restrictive eating problems drastically increased odds of all psychiatric problems, especially autism spectrum disorder in both sexes (odds ratio = 11.9 in boys, odds ratio = 10.1 in girls), obsessive-compulsive disorder in boys (odds ratio = 11.6) and oppositional defiant disorder in girls (odds ratio = 9.22). Comorbid gastrointestinal problems, such as lactose intolerance (odds ratio = 4.43) and constipation (odds ratio = 2.91), were the most frequent in girls. Boy co-twins to a proband with restrictive eating problems generally had more psychiatric problems than girl co-twins and more girl co-twins had neither somatic nor any psychiatric problems at all. Conclusions In chi, Funders: ALF, Skåne; Dr. Sten Theander’s foundation for research in Anorexia Nervosa.

Neurodevelopmental disorders affect a substantial minority of the general population. Their origins are still largely unknown, but a complex interplay of genetic and environmental factors causing disturbances of the central nervous system's maturation and a variety of higher cognitive skills is presumed. Only limited research of rather small sample size and narrow scope has been conducted in neurodevelopmental disorders using a twin-differences design. The Roots of Autism and ADHD Twin Study in Sweden (RATSS) is an ongoing project targeting monozygotic twins discordant for categorical or dimensional autistic and inattentive/hyperactive-impulsive phenotypes as well as other neurodevelopmental disorders, and typically developing twin controls. Included pairs are 9 years of age or older, and comprehensively assessed for psychopathology, medical history, neuropsychology, and dysmorphology, as well as structural, functional, and molecular brain imaging. Specimens are collected for induced pluripotent (iPS) and neuroepithelial stem cells, genetic, gut bacteria, protein-/monoamine, and electron microscopy analyses. RATSS's objective is to generate a launch pad for novel surveys to understand the complexity of genotype-environment-phenotype interactions in autism spectrum disorder and attention-deficit hyperactivity disorder (ADHD). By October 2013, RATSS had collected data from 55 twin pairs, among them 10 monozygotic pairs discordant for autism spectrum disorder, seven for ADHD, and four for other neurodevelopmental disorders. This article describes the design, recruitment, data collection, measures, collected pairs' characteristics, as well as ongoing and planned analyses in RATSS. Potential gains of the study comprise the identification of environmentally mediated biomarkers, the emergence of candidates for drug development, translational modeling, and new leads for prevention of incapacitating outcomes

Background: Forensic psychiatric patients present a challenge as they manifest severe mental disorders together with criminal behaviour. There are well-known risk factors for criminal behaviour in the general population, yet knowledge of what predicts reconviction in the Swedish forensic population in the long-term perspective is still insufficient. Aims: The study aims to (1) describe background and clinical characteristics of forensic psychiatric patients in a 10-year follow-up, (2) analyse risk factors associated with recidivism, and (3) test the predictive validity of risk factors for general and violent criminality. Methods: Detailed information on all offenders from the Malmö University Hospital catchment area sentenced to forensic psychiatric in-patient treatment from 1999–2005 (n = 125) was collected. Court decisions were collected up until the end of 2008 (median follow-up time = 6.2 years, range = 0.6–9.7 years). Results: Relapse in general crime (n = 30) was predicted by low educational attainment, mental disorder in a first degree relative, and low age at first sentenced crime. Relapse in violent crime (n = 16) was predicted by low educational attainment and low GAF scores. Patients with a restriction order were less likely to relapse in both crime categories. Conclusions: Signs of childhood adversities together with early debut in criminality appeared as important risk factors for general and violent recidivism. Forensic psychiatric treatment combined with a restriction order was demonstrated as a protective factor against recidivism, suggesting that the risk of recidivism is strongly related to the level of supervision. Although the low number of recidivism cases is highly desirable, it unfortunately reduces the power of the analyses in this paper.

Background: Antisocial personality and psychopathic traits have constantly been found to accompany criminal and aggressive behaviors, but little attention has been given to aspects of character maturity and its relation to such behaviors. The present study investigated (1) whether level of character maturity (low, medium, and high) is associated with amount of aggressive antisocial behaviors (AABs) and psychopathic traits in young men imprisoned for violent criminality, and (2) whether such an association is independent of coexisting attention-deficit hyperactivity disorder (ADHD). Methods: Swedish males (N = 270, aged 18–25) sentenced to prison for violent and/or sexual criminality in the western region of the Swedish Prison and Probation Service underwent a thorough clinical examination during their in carceration. Data on character maturity, as measured by the character dimensions Self-Directedness and Cooperativeness of the Temperament and Character Inventory, were available for n = 148 subjects and were used to divide these offenders into three groups with low, medium, and high character maturity. These groups were then compared for variables reflecting criminal history, a DSM-IV diagnosis of ADHD, conduct disorder (CD) and substance use disorders (SUD), aggressive behaviors, and psychopathic traits. Results: Character maturity was consistently associated with less AABs and psychopathic personality traits; the group with the highest character maturity showed: (i) a later age at on set of criminality, (ii) a smaller number of prior violent criminal acts, (iii) lower prevalence of ADHD, CD, and SUD, (iv) less self-rated and expert-rated aggressive behaviors, and (v) less psychopathic traits. The association between character maturity and aggressive behaviors/psychopathic personality traits remained even when ADHD was controlled for. The only exception was sexual criminality, where the group with the highest character maturity contained the largest amount of sexu, Funders: Kriminalvården; Region Skåne; Region Kronoberg; StitelsenLindhaga.

BACKGROUND: The character higher order scales (self-directedness, cooperativeness, and self-transcendence) in the temperament and character inventory are important general measures of health and well-being [Mens Sana Monograph 11:16-24 (2013)]. Recent research has found suggestive evidence of common environmental influence on the development of these character traits during adolescence. The present article expands earlier research by focusing on the internal consistency and the etiology of traits measured by the lower order sub-scales of the character traits in adolescence. METHODS: The twin modeling analysis of 423 monozygotic pairs and 408 same sex dizygotic pairs estimated additive genetics (A), common environmental (C), and non-shared environmental (E) influences on twin resemblance. All twins were part of the on-going longitudinal Child and Adolescent Twin Study in Sweden (CATSS). RESULTS: The twin modeling analysis suggested a common environmental contribution for two out of five self-directedness sub-scales (0.14 and 0.23), for three out of five cooperativeness sub-scales (0.07-0.17), and for all three self-transcendence sub-scales (0.10-0.12). CONCLUSION: The genetic structure at the level of the character lower order sub-scales in adolescents shows that the proportion of the shared environmental component varies in the trait of self-directedness and in the trait of cooperativeness, while it is relatively stable across the components of self-transcendence. The presence of this unique shared environmental effect in adolescence has implications for understanding the relative importance of interventions and treatment strategies aimed at promoting overall maturation of character, mental health, and well-being during this period of the life span., Published: 12 March 2016

Background: Autistic-like traits (ALTs) are continuously distributed in the general population, with the autism spectrum disorder (ASD) at the upper extreme end. A genetic overlap has been shown between ALTs and ASD, indicating that common variation in ASD candidate genes may also influence ALTs. In our study, we have investigated the SNP rs4307059 that has been associated with both ALTs and ASD. In addition, we genotyped polymorphisms in a selection of genes involved in synaptic functioning, that is, SHANK3, RELN, and CNTNAP2, which repeatedly have been associated with ASD. The possible associations of these polymorphisms with ALTs, as well as genetic factors for neurodevelopmental problems (NDPs), were investigated in a large cohort from the general population: The Child and Adolescent Twin Study in Sweden. For analyses of ALTs and NDPs, 12,319 subjects (including 2,268 monozygotic (MZ) and 3,805 dizygotic (DZ) twin pairs) and 8,671 subjects (including 2,243 MZ and 2,044 DZ twin pairs), respectively, were included in the analyses. Findings: We could not replicate the previous association between rs4307059 and social communication impairment. Moreover, common variations in CNTNAP2 (rs7794745 and rs2710102), RELN (rs362691), and SHANK3 (rs9616915) were not significantly associated with ALTs in our study. Conclusions: Our results do not suggest that the investigated genes, which previously has been found associated with ASD diagnosis, have any major influence on ALTs in children from the general population.

BACKGROUND: Asthma and attention-deficit/hyperactivity disorder (ADHD) are prevalent in childhood and may cause functional impairment and stress in families. Previous research supports an association between asthma and ADHD in children, but several aspects of this relationship are unclear. OBJECTIVE: Our aim was to study whether the association between asthma and ADHD is restricted to either the inattentive or the hyperactive/impulsive symptoms of ADHD, to explore the impact of asthma severity and asthma medication and the contribution of shared genetic and environmental risk factors on the asthma-ADHD relationship. METHODS: Data on asthma, ADHD, zygosity and possible confounders were collected from parental questionnaires at 9 or 12 years on 20 072 twins through the Swedish Twin Register, linked to the Swedish Medical Birth Register, the National Patient Register and the Prescribed Drug Register. The association between asthma and ADHD, the impact of asthma severity and medication, was assessed by generalized estimating equations. Cross-twin-cross-trait correlations (CTCT) were estimated to explore the relative importance of genes and environment for the association. RESULTS: Asthmatic children had a higher risk of also having ADHD [odds ratio (OR) 1.53, 95% confidence interval (CI): 1.16-2.02]. The association was not restricted to either of the two dimensions of ADHD. The magnitude of the association increased with asthma severity (OR 2.84, 95% CI: 1.86-4.35) for ≥ 4 asthma attacks in the last 12 months and was not affected by asthma treatment. The CTCTs possibly indicate that the genetic component in overlap of the disorders is weak. CONCLUSIONS AND CLINICAL RELEVANCE: Childhood asthma, especially severe asthma, is associated with ADHD. Asthma medication seems not to increase the risk of ADHD. Clinicians should be aware of the potential of ADHD in asthma. Optimal asthma care needs to be integrated with effective evaluation and treatment of ADHD in children with