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Specific Brain Pathways Predict ADHD Impulsivity
Impulsivity differences in young people with attention-deficit/hyperactivity disorder (ADHD) can be predicted by the limbic and executive meso- and nigrostriatal tracts in the brain, suggest study findings published online ahead of print in Biological Psychiatry: Cognitive Neuroscience and Neuroimaging.
“The meso- and nigrostriatal pathways of the dopamine system are hypothesized to be functionally heterogeneous, supporting diverse cognitive functions and impairments, including those associated with ADHD,” wrote lead and corresponding author Blake L. Elliott, PhD, of Arizona State University in Tempe, and coauthors. “We tested whether human midbrain pathways (where dopaminergic cell bodies originate) between the substantia nigra (SN) and ventral tegmental area (VTA) and the striatum differed between participants with ADHD and typically developing adolescent and young adult participants.”
The study included 155 participants who underwent diffusion tensor imaging. Parent- and self-reported ratings, as well as task-based behavioral measures, were used to gauge impulsivity. Researchers used correlation and machine learning to assess for links between tract probabilities and impulsivity.
Related: Generalized Anxiety Disorder Affects 1 in 4 Adults with ADHD
Compared with participants without ADHD, those with ADHD had stronger connectivity between SN/VTA regions and the limbic striatum and weaker connectivity with the executive striatum, the study showed. Sensorimotor tracts did not differ between the groups.
Greater impulsivity could be predicted by increased tract integrity between the limbic striatal and SN/VTA regions, researchers reported. On the other hand, reduced impulsivity could be predicted by increased integrity between executive striatal and SN/VTA regions.
“These findings support the theory that functional diversity in the dopamine system is an important consideration for understanding dysfunction in ADHD,” researchers wrote.
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