THE ANTIDEPRESSANT EFFECTS OF PHYSICAL ACTIVITY: NEUROBIOLOGICAL MECHANISMS AND PSYCHOSOCIAL MECHANISMS

Background: Depression is a leading cause of disability worldwide, affecting millions and imposing significant personal, social, and economic burdens. While pharmacological and psychotherapeutic interventions are standard treatments, physical activity has emerged as a promising complementary or alternative strategy. Methods: A comprehensive literature review was conducted of peer-reviewed studies published between 2000 and 2025, including randomized controlled trials, meta-analyses, and observational research. Populations examined included adolescents, adults, and older adults. Data extraction focused on depressive symptom outcomes, exercise modalities, intervention duration and intensity, and underlying neurobiological and psychosocial mechanisms. Results: Evidence consistently indicates that regular physical activity, particularly aerobic and combined aerobic–resistance exercise, produces moderate to large reductions in depressive symptoms. Mechanistically, exercise enhances brain-derived neurotrophic factor (BDNF) expression, modulates monoaminergic neurotransmission, regulates the hypothalamic–pituitary-adrenal (HPA) axis, and reduces systemic inflammation. Psychosocial benefits, including behavioral activation, increased self-efficacy, and social engagement, further support sustained mood improvement. Combined interventions often yield the greatest effect, integrating biological, psychological, and social pathways. Conclusion: Physical activity is a safe, accessible, and effective intervention for depression, with benefits extending beyond symptom reduction to improved cognitive function, stress resilience, and overall well-being. Incorporating structured exercise into standard treatment protocols may optimize clinical outcomes and support long-term mental health across diverse populations.