March 22, 2018
Executive functions — cognitive abilities related to planning, organizing, and remembering information — are often deficient in children with attention deficit disorder (ADHD or ADD). Now, a new study1 finds that children with autism spectrum disorder (ASD) share many of the same executive functioning challenges — potentially solidifying the working scientific theory that ADHD and autism share genetic factors, researchers said.
The study, published last month in the Journal of Abnormal Child Psychology, looked at nearly 1,000 children — making it among the largest to directly compare symptoms of ADHD and autism, its authors said. Of those children studied, 509 had ADHD, 97 were on the autism spectrum, and 301 served as controls. All children were between the ages of 5 and 17, and all underwent the same six tests measuring executive functions and cognitive abilities.
Both the children with ADHD and those with autism scored significantly worse than did the control group in memory, impulse control, and processing speed. The groups showed virtually the same results in most areas, the researchers said — even when they controlled for symptom severity, hyperactivity, or communication challenges across the ADHD and autism groups.
The clear similarities in executive functioning abilities may be linked to genetic roots shared by ADHD and autism, said lead author Sarah Karalunas, Ph.D., of Oregon Health and Science University.
“Because they occur in both disorders independently, [these executive function deficits] may be associated with some kind of shared liability or shared genetic risk,” she concluded. A follow-up study, which is awaiting funding, will focus on communication challenges associated with both disorders, she said.
There was one significant difference in executive functioning between the two active groups, the researchers found. Whereas children with ADHD responded to reaction tests with a mix of accuracy and speed, children with autism tended to heavily favor accuracy and more methodical decision-making — often sacrificing speed in the process.
“I think [the researchers] have found something that is very, very interesting,” said autism expert Uta Frith, Ph.D., in an interview with Spectrum. “The subjects with autism need more evidence before they actually make their decision, so they are more cautious.” Understanding the reason for this discrepancy may help researchers of both conditions further tease out symptoms and develop more specialized treatment plans, experts said.
“The field has been looking for studies like this,” said Benjamin Yerys, Ph.D., of the Center for Autism Research at the Children’s Hospital of Philadelphia. Neither he nor Dr. Frith, who studies autism at University College London, were involved in the study.
1 Karalunas, Sarah L., et al. “Overlapping and Distinct Cognitive Impairments in Attention-Deficit/Hyperactivity and Autism Spectrum Disorder without Intellectual Disability.” Journal of Abnormal Child Psychology, 15 Feb. 2018, doi:10.1007/s10802-017-0394-2.