Association of Autism Spectrum Disorder with Obsessive-Compulsive and Attention-Deficit/Hyperactivity Traits and Response Inhibition in a Community Sample.

van der Plas et al. (2016) asked a large community sample about autism, ADHD, and OCD traits. They also gave everyone a quick stop-signal task to measure response inhibition.

The team counted how many traits each person had. They also checked if having an autistic sibling raised trait levels in the brother or sister.

People with ASD showed more ADHD and OCD traits and slower inhibition. Siblings of autistic people also carried extra ADHD traits even when they did not have ASD themselves.

The link held for both boys and girls and across age groups.

The finding backs up Green et al. (2015) who saw the same ADHD-ASD overlap in younger children. It also extends Reus et al. (2013) by showing the inflation happens outside clinics, not just in referred families.

Tonizzi et al. (2022) meta-analysis seems to disagree at first glance. That review says inhibition deficits are small when you pool many lab tasks. The difference is method: Ellen used one quick real-life style task while Irene averaged many strict lab tests. Both can be true—day-to-day inhibition slips even if lab scores look near normal.

Finally, the sibling result echoes Mulligan et al. (2009) who first flagged that autism traits run in ADHD families. Ellen confirms the pattern in a broader community sweep.

Screen for ADHD and OCD features whenever you assess a client with ASD—the odds are high. Also screen brothers and sisters; they may show ADHD traits that disrupt home and school even without an ASD diagnosis. Plan interventions that build inhibition skills for the whole family, not just the identified client.