Short‐Term Effects of Aerobic Exercise on Brain Connectivity in Individuals With Subthreshold Depression

BACKGROUND: Subthreshold depression (StD) is a significant risk factor for major depressive disorder (MDD). Aerobic exercise can alleviate depressive symptoms in StD over a certain period and prevent progression from StD to MDD. However, the underlying mechanisms of aerobic exercise on StD remain unclear. METHODS: The current study included 44 individuals with StD and 34 healthy controls (HCs) to perform 8-week aerobic exercise. Then we used Granger causality analysis (GCA) and frequency-dependent functional connectivity (FC) with the bilateral hippocampus to examine the between-group and within-group differences. Support vector machine (SVM) was used to test whether differences in brain regions before aerobic exercise could effectively distinguish between StD and HCs. Finally, we evaluated the relationship between GCA or FC and clinical characteristics in individuals with StD. RESULTS: Before aerobic exercise, StD showed altered GCA and frequency-dependent FC in brain regions related to cognitive control and visual processing. SVM results demonstrated that the current classifier has an accuracy of 80.77% for distinguishing StD and HCs. The results suggested that aerobic exercise could reduce depression and anxiety levels and restore the abnormal GCA and frequency-dependent FC. CONCLUSION: Our study demonstrated further evidence for the short-term effects of aerobic exercise on depression and anxiety in StD and indicated that aerobic exercise can restore aberrant brain connectivity patterns in StD, specifically within a short-term timeframe.