Abstract
Traits of autistic spectrum disorders (ASD) occur frequently in attention deficit hyperactivity disorder (ADHD), but the significance of their presence in terms of phenotype and underlying neurobiology is not properly understood. This analysis aimed to determine whether higher levels of autistic traits, as measured by the Social Communication Questionnaire (SCQ), index a more severe presentation in a large, rigorously phenotyped sample of children with ADHD (N = 711). Regression analyses were used to examine association of SCQ scores with core ADHD features, clinical comorbidities and cognitive and developmental features, with adjustment for putative confounders. For outcomes showing association with total SCQ score, secondary analyses determined levels of differential association of the three ASD sub-domains. Results suggest that increasing ASD symptomatology within ADHD is associated with a more severe phenotype in terms of oppositional, conduct and anxiety symptoms, lower full-scale IQ, working memory deficits and general motor problems. These associations persisted after accounting for ADHD severity, suggesting that autistic symptomatology independently indexes the severity of comorbid impairments in the context of ADHD. Sub-domain scores did not show unique contributions to most outcomes, except that social deficits were independently associated with oppositional symptoms and repetitive behaviours independently predicted hyperactive-impulsive symptoms and motor problems. It would be worthwhile for clinicians to consider levels of socio-communicative and repetitive traits in those with ADHD who do not meet diagnostic criteria for ASD, as they index higher levels of phenotypic complexity, which may have implications for efficacy of interventions.Electronic supplementary materialThe online version of this article (doi:10.1007/s00787-013-0398-6) contains supplementary material, which is available to authorized users.
Highlights
The Social Communication Questionnaire (SCQ) scores in our sample are lower than reported in children ascertained primarily in terms of a diagnosis of autistic spectrum disorders (ASD), as would be expected given that this sample consists of children with attention deficit hyperactivity disorder (ADHD) and those with a clinician’s diagnosis of ASD were not included
The results on the whole suggest that autistic symptomatology, as indexed by total SCQ scores, within ADHD is associated with a more severe phenotype in terms of several clinical, cognitive and developmental features
The results show that higher SCQ scores predict greater severity of ADHD symptoms and greater likelihood of combined subtype, more comorbid oppositional defiant disorder (ODD), conduct disorder (CD), anxiety and depression symptoms, lower cognitive ability and a greater rate of general developmental problems
Summary
There are some important differences (e.g., core symptom definition and recommended treatment), ASD and ADHD share many similar impairments in developmental and cognitive domains. Both are substantially more common in boys than girls, with a gender ratio of around 6:1 [1, 2]. There is strong comorbidity of both disorders with intellectual disability (ID) [3,4,5,6] Both are associated with other specific learning and developmental problems, notably reading difficulties [7,8,9] and motor problems, including developmental co-ordination disorder [10, 11]. Specific speech and language problems similar to those in ASD are
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
