Effects of a 12-week high-intensity interval training intervention on serum neurotransmitters and autonomic function in mild-to-moderate depression.

BACKGROUND: Exercise is increasingly recognized as an effective adjunctive treatment for depression; however, the neurobiological mechanisms underlying its antidepressant effects remain incompletely understood. This study investigated whether a 12-week high-intensity interval training (HIIT) program could alleviate depressive symptoms by modulating peripheral neurotransmitter profiles and autonomic nervous system function in university students with mild-to-moderate depression. METHODS: A total of 34 university students (18-25 years) with mild-to-moderate depression were enrolled and allocated to either an exercise group (EXD, n = 17) or a control group (CON, n = 17). Participants in the EXD group underwent a supervised 12-week HIIT intervention consisting of three 60-min sessions per week, while participants in the CON group continued to receive their usual clinical care without additional structured exercise training. Depressive symptoms were evaluated using the Beck Depression Inventory (BDI) and the Hamilton Depression Rating Scale (HAMD-17). Autonomic nervous system function was assessed by heart rate variability (HRV), and peripheral serum concentrations of serotonin (5-HT), brain-derived neurotrophic factor (BDNF), cortisol, and glutamate were measured before and after the intervention. RESULTS: Compared with the CON group, participants in the EXD group exhibited significantly greater reductions in BDI and HAMD-17 scores, accompanied by marked increases in serum 5-HT and BDNF levels and significant decreases in cortisol and glutamate concentrations (p < 0.05). Both groups exhibited significant within-group improvements in time-domain HRV parameters, including SDNN, RMSSD and HF power. Low-frequency (LF) power increased significantly only within the EXD group; however, no significant between-group differences were observed for any HRV parameters, including LF power and the LF/HF ratio. CONCLUSION: A 12-week HIIT program effectively alleviated depressive symptoms and improved autonomic nervous system function in young adults with mild-to-moderate depression.