Exercise-related changes in depressive symptoms and their association with anterior cingulate cortical thickness.

Aerobic exercise is associated with reduced depressive symptoms, but the neurobiological processes supporting this effect remain incompletely understood. We investigated whether short-term aerobic exercise reduces depressive symptoms in healthy young adults and whether such reduction is related to cortical structural change and neurotransmitter-receptor organization. Forty-eight participants completed a two-week aerobic running intervention and a two-week control period, with depressive symptoms and structural MRI assessed at baseline, week 2 and week 4. Aerobic exercise significantly reduced depressive symptoms relative to the control period. Across individuals, greater symptom reduction was associated with larger increases in anterior cingulate cortical thickness, an association observed only during the active intervention. The cortical map of this symptom-thickness association showed selective spatial correspondence with normative distributions of serotonergic 5-HT1A, 5-HT1B, 5-HT2A and 5-HT4 receptors, and the glutamatergic mGluR5 receptor, and this correspondence was observed only during the exercise period. These results indicate that short-term aerobic exercise is associated with changes in depressive symptoms and anterior cingulate structure. They also provide a neurobiologically informed context for understanding these exercise-related changes.