Effect of physical exercise training on neural activity during working memory in major depressive disorder

Abstract

Background

Deficits in working memory (WM) are common in patients with Major Depression Disorder (MDD). Previous research mainly in healthy adults indicated that physical exercise training may improve cognitive functions by stimulating neuronal plasticity particularly in hippocampal structures. Thus, the goal of this functional Magnetic Resonance Imaging (fMRI) study was to examine alterations in neuronal activity during a WM task and to investigate changes in brain volume and functioning following a physical exercise training in patients with MDD with a specific focus on hippocampal structures.

Methods

86 (39 female) MDD outpatients (average age 37.3), diagnosed by clinical psychologists, were randomly assigned to one of three groups for a 12-week intervention: High intensity exercise training (HEX), low intensity exercise training (LEX) or waiting list control group (WL). An n-back task (with WM loads of 0, 1, 2, and 3) during fMRI was conducted before and after interventions/waiting period.

Results

Both exercise groups showed better performance and shorter reaction times at higher WM loads after 12-weeks of physical exercise training. Specifically in the HEX, we found an improvement in physical fitness and an increase in neural activation in the left hippocampus as compared to the WL following the exercise training. Training-related structural volume changes in gray matter or hippocampus were not detected.

Conclusions

Our results partly support the hypothesis that physical exercise training positively affects WM functions by improving neuronal plasticity in hippocampal regions. Exercise training seems to be a promising intervention to improve deficient WM performance in patients with MDD.

Clinical trials registration name

Neurobiological correlates and mechanisms of the augmentation of psychotherapy with endurance exercise in mild to moderate depression - SPeED, http://apps.who.int/trialsearch/Trial2.aspx?TrialID=DRKS00008869, DRKS00008869.