Aerobic Exercise, Cognitive Performance, and Brain Activity in Adolescents with Attention-Deficit/Hyperactivity Disorder.

Abstract

Attention-Deficit/Hyperactivity Disorder (ADHD) is a neurodevelopmental disorder for which behavioural treatments such as exercise are recommended as part of a multi-disciplinary treatment program. Exercise improves executive function in individuals with ADHD, but limited information exists regarding the mechanisms involved in the response. We examined task-evoked brain responses during exercise and seated rest in 38 adolescents (n = 15 ADHD; age = 13.6+/-1.9, male = 73.3%, n = 23 typically developing (TD; age = 13.3+/-2.1, male = 56.5%)). Participants completed a working memory and inhibitory task while cycling at a moderate intensity for 25 minutes (i.e., exercise condition) and while seated on the bike without pedalling (i.e., control condition). Conditions were randomized and counter-balanced. Functional near-infrared spectroscopy measured relative changes in oxygenated hemoglobin concentration in 16 brain regions-of-interest. Brain activity for each cognitive task and condition was examined using linear mixed effects models with a false discovery rate correction (FDR). The ADHD group had slower response speeds for all tasks and lower response accuracy in the working memory task during exercise compared to the TD group (p < 0.05). For the inhibitory task, the ADHD group had lower brain activity in the inferior/superior parietal gyrus during exercise compared to the control condition, while the opposite was true for TD (FDRcorrected, p < 0.05). For the working memory task, higher brain activity during exercise was observed, regardless of group, in the middle and inferior frontal gyrus and the temporoparietal junction (FDRcorrected, p < 0.05). Dual-task performance is challenging for adolescents with ADHD and exercise may modulate neuronal resources in regions such as the temporoparietal junction and frontal areas known to be hypoactive in this population. Future research should examine how these relationships change over time.