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. 2014 Apr 30;17(3):83. doi: 10.1136/eb-2014-101804

Autism traits may be more prevalent in ADHD than previously reported

Kevin Antshel 1
PMCID: PMC13404252  PMID: 24785735

What is already known on this topic?

Previous research has indicated that there are qualitative and quantitative differences in the behavioural phenotypes of autism spectrum disorder (ASD) and attention-deficit/hyperactivity disorder (ADHD).1 The presence of ASD traits in children with ADHD, however, generally portends a more severe profile of symptoms and impairments. Cooper and colleagues’ study is novel due to the very large sample size of children with ADHD, and because it assesses ASD traits on a continuous scale.

What does this paper add?

  • ASD traits in children with ADHD were associated with lower familial socioeconomic status, higher levels of oppositional and/or defiant behaviours (especially aggression), and more working memory impairments, independent of ADHD severity.

  • ASD traits may be more prevalent in ADHD than previously reported. The mean Social Communication Questionnaire (SCQ) score reported by parents (13) is close to the SCQ screening threshold (15) for further consideration of ASD.

Limitations

  • Several of the SCQ items (eg, ‘complicated movements of the body’) may be interpreted by parents as hyperactivity, thus artificially inflating ASD trait levels in ADHD.

  • There is an under-representation of children with mood disorders, anxiety disorders and the ADHD-inattentive subtype. This may affect the external validity of these data.

  • The ADHD sample was ascertained clinically. Thus, there may be a referral bias towards those children who have a more severe phenotype. This may also affect the external validity of these data.

What next in research?

A longitudinal study would permit a better understanding of the direction of the relationship between ASD traits and ADHD symptoms. In addition, studies should focus on how the presence of ASD traits affects standard, evidence-based interventions for children with ADHD. For example, some data suggest that ADHD negatively affects a standard ASD intervention.2

Could these results change your practices and why?

Clinicians should assess for ASD traits in children with ADHD. Diagnostic overshadowing occurs when behaviours are ascribed to one condition without consideration of an alternative explanation. Thus, rather than assuming that ASD traits are subsumed by an ADHD diagnosis, clinicians would be wise to consider the possibility of a comorbid condition. Higher levels of ASD traits may portend a more severe phenotype that might affect the intensity and duration of any proposed intervention. Interventions designed to reduce oppositional behaviours (eg, parent management training and school-based behavioural interventions) may be worth considering for parents of children with ADHD and higher levels of ASD traits.

Footnotes

Competing interests: None.

References

  • 1.Antshel KM, Zhang-James Y, Faraone SV. The comorbidity of ADHD and autism spectrum disorder. Expert Rev Neurother 2013;13:1117–28. [DOI] [PubMed] [Google Scholar]
  • 2.Antshel KM, Polacek C, McMahon M, et al. Comorbid ADHD and anxiety affect social skills group intervention treatment efficacy in children with autism spectrum disorders. J Dev Behav Pediatr 2011;32:439–46. [DOI] [PubMed] [Google Scholar]
Evid Based Ment Health. 2014 Apr 30;17(3):83.

Commentary

ABSTRACT FROM Cooper M, Martin J, Langley K, et al. Autistic traits in children with ADHD index clinical and cognitive problems. Eur Child Adolesc Psychiatry 2014;23:23–34.

Population Seven hundred and eleven children aged between 5 and 18 years (mean age 10.3 years; 84% male) with a Diagnostic and Statistical Manual of Mental Disorders (DSM)-III-R or DSM-IV diagnosis of attention-deficit/hyperactivity disorder (ADHD; including subtype as measured using the parent version of the Child and Adolescent Psychiatric Assessment), and with identifiable autistic spectrum disorder (ASD) traits (measured using Social Communication Questionnaire (SCQ) scores, where higher scores reflect a stronger ASD trait). Exclusion criteria included a diagnosis of ASD, schizophrenia, epilepsy or other neurological disorder, bipolar disorder or Tourette's syndrome.

Setting Child psychiatry and paediatric outpatient units in the UK.

OUTCOMES

Association between ASD traits and ADHD subtypes Higher SCQ scores were significantly associated with a DSM-IV diagnosis of ADHD combined subtype (OR=1.06, 95% CI 1.03 to 1.09). SCQ scores also had a significant positive association with number of inattentive, hyperactive-impulsive symptoms and total number of ADHD symptoms. This pattern of results remained consistent after adjusting for covariates (IQ, age, gender and family socioeconomic status) and accounting for multiple testing.

Association between ASD traits in ADHD and oppositional defiant disorder (ODD), conduct disorder (CD) and anxiety

Higher SCQ scores were significantly associated with a diagnosis of DSM-IV oppositional defiant disorder (ODD) (OR=1.03, 95% CI 1.01 to 1.06), conduct disorder (CD) (OR=1.06, 95% CI 1.03 to 1.09) and any diagnosis of anxiety (generalised anxiety disorder, social anxiety or separation anxiety; OR=1.06, 95% CI 1.02 to 1.11). Higher SCQ scores were also significantly associated with increased ODD and CD symptoms. This pattern of results remained consistent after adjusting for covariates (IQ, age, gender, family socioeconomic status and ADHD severity) and accounting for multiple testing.

Association between ASD traits in ADHD and cognitive and developmental outcomes Higher SCQ scores were significantly negatively associated with IQ (Wechsler Intelligence Scale for Children, WISC-III and WISC-IV) and with verbal working memory (Digit Span subtest). Higher SCQ scores were also associated with a higher prevalence of motor problems (OR=1.09, 95% CI 1.06 to 1.12) and language problems (OR=1.07, 95% CI 1.04 to 1.10), as assessed by responses from general questions put to the parents. No significant association was found between higher SCQ scores and executive function (Cambridge Neuropsychological Battery (CANTAB)), or basic reading, spelling or reading comprehension (Wechsler Objective Reading Dimensions (WORD)). This pattern of results remained consistent after adjusting for covariates (IQ, age, gender, family socioeconomic status and ADHD severity) and accounting for multiple testing.

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