Different Types of ADHD Are Rooted In Different Areas of the Brain, Study Says
A study suggests that instead of being one disorder with small variations, ADHD may actually be a collection of discrete disorders, each originating in a separate area of the brain.
January 9, 2018
A recent brain imaging study1 suggests that different ADHD subtypes each originate in a distinct part of the brain, and may in fact be separate disorders. The results, if replicated, would challenge long-standing beliefs that ADHD is one disorder with several common variations, and may open the door to more personalized treatment strategies, the study’s authors said.
The study, published last year in Biological Psychiatry: Cognitive Neuroscience and Neuroimaging, examined 117 adolescents between the ages of 12 and 17 who had been diagnosed with ADHD. Initially, researchers tested each child’s executive functions and tendency towards immediate rewards, and used the results to divide them into 3 groups: one that struggled solely with executive functions, one that struggled with both executive functions and reward management, and a third that performed similarly to children without ADHD on both tests. Each child then underwent an fMRI scan.
The scans revealed that each of the three groups demonstrated a separate brain abnormality, closely linked to their specific type of impairment. Executive function deficits, for instance, originated in one area of the brain, while impulsive responses to rewards were reflected in another area. No single brain abnormality was shared by all three groups — indicating to the researchers that different treatments aimed at these unique brain patterns may be the next step.
“It certainly is possible to design studies that are tailored for different types of neurobiological impairments,’’ said lead author Michael Stevens, Ph.D., from Yale University “Behavioral therapies designed for a particular type of motivational style might be more effective for some patients, while medications more effective for others.’’
But treatment personalization may still be far in the future. “The most important thing at this point is to increase the awareness that not every patient who meets diagnostic criteria for ADHD has symptoms that arise from the same neurobiological abnormality,” he said.
“Once the field gets comfortable with the idea that this assumption is a roadblock to progress,” he concluded, “we can get down to the business of conceptualizing new treatments based on different suspected etiologies.”
1 Stevens, Michael C., et al. “Functional Neuroimaging Evidence for Distinct Neurobiological Pathways in Attention-Deficit/Hyperactivity Disorder.” Biological Psychiatry: Cognitive Neuroscience and Neuroimaging, 2017, doi:10.1016/j.bpsc.2017.09.005.