Abstract
Breast cancer is a significant traumatic experience that often leads to chronic stress and mental health challenges. Research has consistently shown that physical activity—especially exercise—can alleviate depressive symptoms; however, the specific biological mechanisms underlying these antidepressant effects remain unclear. In this review, we comprehensively summarize the biological mechanisms of depression and the antidepressant mechanisms of physical activity and explore the biological processes through which exercise exerts its antidepressant effects in breast cancer patients. We focus on the impact of physical activity on inflammation, the endocrine system, glutamate, and other aspects, all of which play crucial roles in the pathophysiology of depression. Moreover, we discuss the heterogeneity of depression in breast cancer patients and the complex interactions between its underlying mechanisms. Additionally, we propose that a deeper understanding of these mechanisms in the breast cancer population can guide the design and implementation of exercise-based interventions that maximize the antidepressant benefits of physical activity. Finally, we summarize the current research and propose future research directions.