Siblings of children with autism or ADHD are at elevated risk for both disorders

Later-born siblings of children with autism spectrum disorder (ASD) or attention-deficit/hyperactivity disorder (ADHD) are at elevated risk for both disorders, a new study led by Meghan Miller, assistant professor in the Department of Psychiatry and Behavioral Sciences and at the UC Davis MIND Institute, has concluded. The findings appear today in JAMA Pediatrics. The study suggests that families who already have a child diagnosed with ASD or ADHD may wish to monitor younger siblings for symptoms of both conditions.
Symptoms of ADHD include difficulty focusing, nonstop talking or blurting things out, increased activity, and trouble sitting still. ASD, on the other hand, involves significant challenges with social interaction and communication, as well as the presence of unusual interests or repetitive behaviors like hand flapping or lining up objects. "We've known for a long time that younger siblings of children with autism are at higher-than-average risk for autism, but the field didn't have adequate data to tell whether they were at increased risk for ADHD," said Miller. "Despite the fact that autism and ADHD appear very different in their descriptions, this work highlights the overlapping risk; younger siblings of children with ASD are at elevated risk of both ADHD and autism, and younger siblings of children with ADHD are at elevated risk not only for ADHD but also for autism."