A randomized trial of aerobic exercise on cognitive control in major depression

Objective: The aim of this study was to examine the effects of an 8-week moderate-intensity aerobic exercise training intervention on cognitive control in individuals with major depressive disorder (MDD). Methods: Participants with a current diagnosis of MDD (n = 30; 21.1 +/- 2.0 years) were stratified by depressive symptoms and randomized to an 8-week intervention of aerobic exercise (AE) or placebo exercise (PE). AE consisted of three sessions/week of moderate-intensity exercise training while PE consisted of three sessions/week of light-intensity stretching. Cognitive control was assessed pre- and post-treatment using behavioral performance (i.e., reaction time and accuracy) and event-related potentials (i.e., N2 amplitude). Depressive symptoms and rumination were also assessed before and after the intervention. Results: Compared with PE, the AE treatment arm was associated with an increase in N2 amplitude to incongruent flanker task trials, reflecting an increase in cognitive control processes. Symptoms of depression also decreased after AE although the treatments did not differ in their effects on rumination. Exploratory mediation analysis indicated that changes in N2 amplitude did not mediate pre-to-post treatment reductions in depressive symptoms. Conclusions: An 8-week moderate-intensity AE program is associated with improved neural indices of conflict monitoring and reduced depressive symptoms among individuals with MDD. Significance: Future research examining the influence of exercise in combination with behavioral and pharmacological treatments for neurocognitive function in MDD is warranted. (C) 2017 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.