Shared genetic influences between dimensional ASD and ADHD symptoms during child and adolescent development.

The study did not test therapy or treatment, so it cannot tell clinicians whether intervening on ADHD symptoms or social-communication difficulties changes the other. The measures were mother-reported questionnaire scores in a general population, not therapist-assessed communication disorders or clinical diagnoses. The study mainly examined common inherited variants in White European samples, so it does not address rare variants or other ancestry groups. The cross-dimensional trait-disorder analyses had low power, with estimates around 0.23 and 0.21, and the authors say much larger clinical samples are needed. The polygenic risk scores explained a very small proportion of trait variance, less than 1%, even when symptoms mapped to the same disorder dimension. The results describe the whole cohort and do not allow inferences about children with extreme behavioural scores, who were a small proportion of the sample, 10% or less. Participants with higher behavioural scores may be more likely to drop out over time, although the authors report little evidence of bias after bootstrapping.

The supplied text names the Wellcome Trust and Autism Speaks as funders.

Do not conclude that ADHD and autism are genetically the same clinical disorder. The study found shared genetic influences between general population social-communication difficulties and ADHD symptoms, but it found little support for links between autism genetic risk and ADHD symptoms or between ADHD genetic risk and social-communication scores, and it tested no interventions.