Younger siblings of children with attention deficit hyperactivity disorder (ADHD) or autism spectrum disorder are more likely to develop either disorder, according to a new study.
According to the findings, younger brothers and sisters of children with ADHD are 13 times more likely to develop ADHD and 4 times more likely to be on the autism spectrum. For children with autism, the likelihood that younger siblings could receive an ADHD diagnosis is 3.5 times higher.
This is the first time the recurrence of ADHD has been examined in younger brothers and sisters of children who have been diagnosed with either ADHD or autism, according to Erica Musser, FIU psychologist and study co-author.
“The findings suggest that ADHD and autism may have some shared causes or risk factors that are clustered within families,” said Musser, a licensed clinical psychologist in the FIU Center for Children and Families. “Identifying these risk factors allows us to improve prevention efforts and screenings targeted at younger siblings of those affected by either disorder.”
The study looked at medical records from 15,175 younger siblings, ages 5 to 18, from two large health care systems in the United States to determine recurrence risk — a common way to measure shared traits in families. The participants were classified by risk for ADHD, risk for autism and those with no known risk, based on the older child’s diagnosis.
With this data, researchers were able to determine younger siblings of children with ADHD are at greater risk of developing either ADHD or autism. The same is true for siblings of children with autism.
“We are still learning about the earliest indicators of autism and ADHD, but we do know that early intervention is key to successful outcomes,” Musser said. “The best option for parents who may be concerned is to mention anything that seems out of the ordinary to their child’s pediatrician and ask for an Ages and Stages Questionnaire or similar developmental screening.”
The study was funded by the National Institute of Mental Health and was conducted in collaboration with the MIND Institute at the University of California Davis and the Marshfield Clinic Research Institute in Wisconsin. It was recently published in the Journal of the American Medical Association Pediatrics.