RESUMEN
INTRODUCTION: The long-term impact of physical activity during early life on the risk of depression in later stages of adulthood remains unclear. This study examines the association between physical activity during childhood and adolescence and the incidence of depressive symptoms in early, middle, and late adulthood. METHODS: Data from a birth cohort (the 1958 National Child Development Survey), including births (N=17,415) in England, Wales, and Scotland, were used. After birth, 11 more follow-ups were carried out between ages 7 and 62 years (2020). Leisure-time physical activity was assessed through a self-reported questionnaire. Psychological measures were assessed with the teacher-rated Bristol Social Adjustment Guide, the teacher-rated Rutter scale, and the self-rated Malaise Inventory. Leisure-time physical activity and psychological symptoms were examined in all the 11 follow-up assessments included in this study. Best-fit model was used to obtain hazard ratios and 95% CIs of depression symptoms by physical activity status in different ages, including demographic, behavioral, and health-related variables as potential confounders. RESULTS: After multivariate analysis, being physically active at age 16 years reduced the risk of incident elevated depressive symptoms (hazard ratio=0.73, 95% CI=0.62, 0.85) throughout adulthood. The long-term impacts of physical activity practiced at age 16 years persisted throughout adulthood up to age 62 years. CONCLUSIONS: Adolescence is a critical early-life period to promote physical activity for reducing the incidence of elevated depressive symptoms throughout adulthood. Public health policies should promote healthy lifestyles during the lifespan to reduce both the burden of physical inactivity and depressive symptoms at the population level.