ADHD Genes Also Influence Social, Cognitive Behaviors
Abstract
Genetic variants associated with a clinical diagnosis of ADHD correlate with lower attention, memory, and social language skills in children without the disorder.
While clinicians have to make categorical decisions when diagnosing attention-deficit/hyperactivity disorder (ADHD), the traits that are characteristic of this disorder—inattentiveness, restlessness, impulsivity—occur at varying levels in every person.
The question has been whether ADHD represents just an extreme of this natural spectrum or an abnormal state of inattention or impulsivity.
Ruane Prize recipient Anita Thapar, M.B.B.Ch., Ph.D., presents her research at the Brain and Behavior Research Foundation symposium on how genetic variants for ADHD risk influence other behavioral traits.
Some new genetic studies suggest the former scenario may be the case. A team led by Anita Thapar, M.B.B.Ch., Ph.D., a professor at the Cardiff University School of Medicine in Wales, found that a cluster of risk genes often found in children with ADHD was also associated with behavioral and cognitive traits among the general population.
The group used the Avon Longitudinal Study of Parents and Children (ALSPAC), a large study that has been monitoring children and their parents since 1991. They obtained genetic data for more than 8,200 ALSPAC children and gave each one a polygenic risk score based on the number of ADHD-associated gene variants they possessed
Thapar had previously found that higher risk scores—composed from a library of thousands of individual variations that individually have a negligible effect on risk—were higher in children with a clinical ADHD diagnosis than in healthy controls.
The new analysis in the ALSPAC group showed that a higher risk score also correlated with more inattention and hyperactivity in children without ADHD, as well as with traits such as pragmatic language, working memory, and IQ.
“What’s interesting is that these traits are not typical diagnostic features of ADHD,” Thapar told Psychiatric News. “So these ADHD risk genes make contributions to other neurocognitive behaviors.”
So in addition to providing molecular evidence to support the idea of ADHD as just one end of a broad behavioral spectrum, the findings also highlight the overlap between ADHD and related childhood disorders like autism spectrum disorder (ASD) and the new DSM-5 category of social communication disorder.
Other behaviors found in patients with ASD, such as social cognition and facial emotion recognition, were not associated with these risk genes, however.
Thapar, who was the recipient of this year’s Brain and Behavior Research Foundation’s Ruane Prize for Outstanding Achievement in Child and Adolescent Research for her contributions to ADHD genetics, hopes that continued analysis and refinement of these risk scores may help identify children with potential learning or attention difficulties, even if they do not manifest as clinical ADHD.
However, as a child clinician herself, she stressed the importance of not extrapolating the results too far in regard to how ADHD is diagnosed and treated.
“These findings are exciting, but as clinicians, we cannot prescribe treatments based on what may happen in the future; our decision making can be based only on what we see and what we know,” she said.
These genetic studies were published as two related papers in Biological Psychiatry and the Journal of Child Psychology and Psychiatry. The work was funded by the United Kingdom Medical Research Council and the Wellcome Trust. ■
An abstract of “Genetic Risk for Attention-Deficit/Hyperactivity Disorder Contributes to Neurodevelopmental Traits in the General Population” can be accessed here. An abstract of “Neurocognitive Abilities in the General Population and Composite Genetic Risk Scores for Attention-Deficit/Hyperactivity Disorder” is available here.
