Increased risk of ADHD in families with ASD

Eur Child Adolesc Psychiatry. 2019 Feb;28(2):281-288. doi: 10.1007/s00787-018-1206-0. Epub 2018 Sep 28.


Attention Deficit and Hyperactive Disorder (ADHD) and Autism Spectrum Disorders (ASD) are frequent comorbid neurodevelopmental conditions and the overlap between both disorders remains to be delineated. A more complete understanding of the shared genetic and environmental factors is needed. Using a family-based method, we evaluated the risk of ADHD in a group of relatives with an ASD proband (ASD-) and a group of relatives with an ASD and ADHD proband (ASD+). We enrolled 1245 individuals in the study: 499 probands, their 746 first-degree relatives and 140 controls. We used a multivariate generalized estimating equation (GEE) model, in which the dependent variable was the ADHD diagnosis in the relatives and the independent variable the ASD+ or ASD- in probands. We adjusted for sociodemographic factors (age, sex, IQ) and for the nature of the familial relationship with the affected proband (parent or sibling). Among the probands, there were 287 ASD- and 212 ASD+ individuals. ADHD was more frequent in relatives (19%) than in the control group (7%) (p = 0.001). The risk of ADHD was higher in the ASD+ relatives group than in the ASD- relatives group (GEE model OR 1.58 [95% CI 1.04-2.38], p = 0.032). This result was found in parents (OR 1.96 [95% CI 1.14-3.36], but not in siblings (OR 1.28 [95% CI 0.84-1.94], p = 0.434). Our study provides a representative estimate of the family distribution of ADHD in relatives of ASD probands but supports the modest effect of shared genetic and environmental factors between both disorders.

Keywords: Attention deficit hyperactivity disorder; Autism spectrum disorder; Familial aggregation; Siblings.

MeSH terms

  • Adolescent
  • Adult
  • Attention Deficit Disorder with Hyperactivity / diagnosis
  • Attention Deficit Disorder with Hyperactivity / genetics*
  • Attention Deficit Disorder with Hyperactivity / psychology
  • Autism Spectrum Disorder / diagnosis
  • Autism Spectrum Disorder / genetics*
  • Autism Spectrum Disorder / psychology
  • Case-Control Studies
  • Child
  • Child, Preschool
  • Family
  • Female
  • Genetic Predisposition to Disease / genetics*
  • Humans
  • Male
  • Middle Aged
  • Parents
  • Siblings / psychology
  • Young Adult