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Autism spectrum disorders (ASD) and attention deficit hyperactivity disorder (ADHD) show high comorbidity. The following questions were addressed regarding their specific symptoms: What is the factor structure of ASD and ADHD symptoms, to what degree do different symptom domains cluster together, to what extent are these domains caused by the same genetic and environmental influences, and what is the best model of their co-occurrence? A population-based twin cohort of over 17,000 9- and 12-year-olds were assessed using the Autism-Tics, AD/HD, and other Comorbidities parental interview inventory. Principal component analyses were conducted, and symptom domain clustering was assessed. Four multivariate twin models were compared. Factors split into three ASD (social impairments, communication impairments, and restricted repetitive behaviors and interests), and three ADHD (inattention, hyperactivity, and impulsivity) symptom domains. Some ASD-ADHD symptom domain combinations clustered together often, although others not at all. A two-factor common pathway model fit the data, suggesting that ASD and ADHD symptom domains tap into separate "ASD" and "ADHD" latent factors that showed high genetic overlap. All subdomains also showed significant specific genetic and environmental influences, reflecting the etiological heterogeneity both within and between ASD and ADHD. These flndings support the conceptual distinction of ASD and ADHD, and demonstrate the considerable natural co-occurrence of particular ASD/ADHD symptom domains. The results imply that more children with 1 condition shov/ features of the other condition than show complete comorbidity. Emphasis on symptom co-occurrence, rather than complete comorhidity between disorders, may help focus clinical approaches and advance molecular genetic research. [ABSTRACT FROM AUTHOR]

Background Although neurodevelopmental disorders are demarcated as discrete entities in the Diagnostic Statistical Manual of mental disorders, empirical evidence indicates that there is a high degree of overlap among them. The first aim of this investigation was to explore if a single general factor could account for the large degree of observed overlap among neurodevelopmental problems, and explore whether this potential factor was primarily genetic or environmental in origin. The second aim was to explore whether there was systematic covariation, either genetic or environmental, over and above that contributed by the potential general factor, unique to each syndrome. Method Parents of all Swedish 9- and 12-year-old twin pairs born between 1992 and 2002 were targeted for interview regarding problems typical of autism spectrum disorders, ADHD and other neurodevelopmental conditions (response rate: 80 percent). Structural equation modeling was conducted on 6,595 pairs to examine the genetic and environmental structure of 53 neurodevelopmental problems. Results One general genetic factor accounted for a large proportion of the phenotypic covariation among the 53 symptoms. Three specific genetic subfactors identified 'impulsivity,' 'learning problems,' and 'tics and autism,' respectively. Three unique environment factors identified 'autism,' 'hyperactivity and impulsivity,' and 'inattention and learning problems,' respectively. Conclusion One general genetic factor was responsible for the wide-spread phenotypic overlap among all neurodevelopmental symptoms, highlighting the importance of addressing broad patient needs rather than specific diagnoses. The unique genetic factors may help guide diagnostic nomenclature, whereas the unique environmental factors may highlight that neurodevelopmental symptoms are responsive to change at the individual level and may provide clues into different mechanisms and treatments. Future research would benefit from assessing the general factor separately from specific factors to better understand observed overlap among neurodevelopmental problems. [ABSTRACT FROM AUTHOR]

Objective: To assess prevalence figures for psychiatric disorders among institutionalized adolescents due to behavioural problems and/or delinquency. Method: Participants were recruited from consecutive referrals to/or treated at two Swedish adolescent units, SIS1 (n = 60) and SIS2 (n = 70) with ranging age of 12-20.3 years (mean age = 16.2; SD = 1.8) during 1 year. Clinical and diagnostic information was used to generate DSM-IV diagnoses. Results: One or several neuropsychiatric disorders were diagnosed in 53% of all subjects: 39% met DSM-IV diagnostic criteria for attention deficit/hyperactivity disorder (AD/HD), 15% for a pervasive developmental disorder (referred to as autism spectrum disorders, ASDs) and 8% had a mental retardation (referred to as a learning disability, LD). The collapsed prevalence for psychiatric disorders requiring specialist attention was 66%, counting severe depression and psychotic disorders but not substance use. About one in three of all adolescents in the study were given psychopharmacological treatment. Conclusion: Published studies and this clinical survey clearly indicate that systematic studies of mental health needs among institutionalized adolescents are warranted to form the basis of adequate treatment and support measures. [ABSTRACT FROM AUTHOR]

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 (βboys =.24, standard error, SE = 0.03; βgirls =.17, SE = 0.03), above and beyond its association with the externalizing (βboys = 0.21, SE = 0.04; βgirls = 0.17, SE = 0.05) and general factors (βboys = 0.45, SE = 0.03; βgirls = 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. [ABSTRACT FROM AUTHOR]

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 children with restrictive eating problems odds of all coexisting psychiatric problems and gastrointestinal problems are significantly increased. The study shows the importance of considering comorbidities in clinical assessment of children with restrictive eating problems. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Objective: Neurodevelopmental problems (NDPs) may influence the transition from childhood to adolescence. Our aim was to study long-term psychosocial outcomes of NDPs, focusing on ADHD. Method: Data was collected through a telephone interview with parents of twins at ages 9 or 12 years. NDP screen-positive children were clinically assessed at age 15; N = 450. Psychosocial outcome concerning peers, school, internalizing problems, antisocial behavior, alcohol misuse, drug misuse, and impaired daily functioning was examined. Results: Even after controlling for other NDP comorbidity, screen-positivity for ADHD doubled or tripled the odds of later psychosocial problems. When controlling for parental education level, the significant effect of ADHD remained only for antisocial behavior and impaired daily functioning. Conclusions: Signs of NDPs as well as other psychiatric diagnoses at ages 9 or 12 years are associated with a more problematic adolescence. However, despite the presence of comorbidity, early ADHD symptoms stand out as the most important risk factor for later antisocial development and impaired daily functioning. [ABSTRACT FROM AUTHOR]

Background Evidence from twin and molecular genetic studies is accumulating that Autism Spectrum Disorder ( ASD) shares substantial etiological factors with other disorders. This is mirrored in clinical practice where ASD without coexisting disorders is rare. The present study aims to examine the range of coexisting disorders in ASD in a genetically informative cohort. Methods Parents of all Swedish 9-year-old twins born between 1992 and 2001 ( n = 19,130) underwent a telephone interview designed to screen for child psychiatric disorders, including ASD. To ensure full coverage of child psychiatric disorders, data were also retrieved from population-based health registers. We investigated the coexistence of eight psychiatric disorders known to coexist with ASDs in probands and their co-twins. Results Half of the individuals with ASDs (50.3%) had four or more coexisting disorders and only 4% did not have any concomitant disorder. The 'healthy co-twin' in ASD discordant monozygotic twin pairs was very often (79% of boys and 50% of girls) affected by at least one non- ASD disorder. The corresponding figures for ASD discordant dizygotic twin pairs were significantly lower (46% of males and 30% of females). Conclusions Detailed phenotypic descriptions including symptoms of problems associated with a wide range of child psychiatric disorders may aid in unraveling the genetic architecture of ASD and should guide the development of intervention strategies addressing each problem type specifically. [ABSTRACT FROM AUTHOR]

The Autism-Tics, AD/HD, and other Comorbidities (A-TAC) inventory is used in epidemiological research to assess neurodevelopmental problems and coexisting conditions. Although the A-TAC has been applied in various populations, data on retest reliability are limited. The objective of the present study was to present additional reliability data. The A-TAC was administered by lay assessors and was completed on two occasions by parents of 400 individual twins, with an average interval of 70 days between test sessions. Intra- and inter-rater reliability were analysed with intraclass correlations and Cohen's κ A-TAC showed excellent test-retest intraclass correlations for both autism spectrum disorder and attention deficit hyperactivity disorder (each at .84). Most modules in the A-TAC had intra-and inter-rater reliability intraclass correlation coefficients of ≥ .60. Cohen's κ indicated acceptable reliability. The current study provides statistical evidence that the A-TAC yields good test-retest reliability in a population-based cohort of children. [ABSTRACT FROM AUTHOR]

Background: Hoarding Disorder (HD) is often assumed to be an ‘old age’ problem, but many individuals diagnosed with HD retrospectively report first experiencing symptoms in childhood or adolescence. We examined the prevalence, comorbidity and etiology of hoarding symptoms in adolescence. Methods: To determine the presence of clinically significant hoarding symptoms, a population-based sample of 15-year old twins (N = 3,974) completed the Hoarding Rating Scale-Self Report. Co-occurring Obsessive Compulsive Disorder (OCD), Autism Spectrum Disorders (ASD) and Attention Deficit Hyperactivity Disorder (ADHD) were estimated from parental report. Model-fitting analyses divided hoarding symptom scores into additive genetic, shared, and non-shared environmental effects. Results: The prevalence of clinically significant hoarding symptoms was 2% (95% CI 1.6–2.5%), with a significantly higher prevalence in girls than boys. Exclusion of the clutter criterion (as adolescents do not have control over their environment) increased the prevalence rate to 3.7% (95% CI 3.1–4.3%). Excessive acquisition was reported by 30–40% among those with clinically significant hoarding symptoms. The prevalence of co-occurring OCD (2.9%), ASD (2.9%) and ADHD (10.0%) was comparable in hoarding and non-hoarding teenagers. Model-fitting analyses suggested that, in boys, additive genetic (32%; 95% CI 13–44%) and non-shared environmental effects accounted for most of the variance. In contrast, among girls, shared and non-shared environmental effects explained most of the variance, while additive genetic factors played a negligible role. Conclusions: Hoarding symptoms are relatively prevalent in adolescents, particularly in girls, and cause distress and/or impairment. Hoarding was rarely associated with other common neurodevelopmental disorders, supporting its DSM-5 status as an independent diagnosis. The relative importance of genetic and shared environmental factors for hoarding differed across sexes. The findings are suggestive of dynamic developmental genetic and environmental effects operating from adolescence onto adulthood. [ABSTRACT FROM AUTHOR]

The objective of this study was to explore how sexual child abusers who meet the DSM-IV criteria for paedophilia differ from those who do not. We studied DSM-IV disorders and paedophilic interests in all cases of sexual child abuse referred to forensic psychiatric investigation in Sweden between 1993 and 1997 ( n =185). Frequency and severity of other mental disorders did not differ between subjects with and without DSM-IV paedophilia. However, men with paedophilia had more previous paedophilia convictions, same-sex and younger victims and less often intoxicated status when committing the act. The concept of paedophilia as a mental disorder is not supported by the DSM-IV diagnosis, which primarily describes the acting out of attraction. [ABSTRACT FROM AUTHOR]