Physical activity during adolescence protects against depression in adulthood: a systematic review and meta-analysis (Preprint)

BACKGROUND Growing evidence indicates physical activity (PA) in early life appear to influence depression development in later life. However, questions remain regarding whether PA during adolescence, a critical early-life period, has a long-term impact on depression in adulthood. OBJECTIVE This systematic review and meta-analysis aimed to examine the association between PA during adolescence and depression in adulthood. METHODS We systematically searched Ovid Medline, Ovid Embase, Ovid Cochrane, and PsycINFO, to identify prospective observational studies that examined the association between PA during adolescence and the risk of depression in adulthood. The literature search was conducted from the inception of these databases to November 17, 2022, with an update to December 20, 2024. Two reviewers independently extracted data and assessed the quality of evidence through Newcastle - Ottawa Scale. We employed a random-effects model with inverse variance weighting to calculate odds ratios (ORs) and 95% confidence intervals (95%CIs). Subgroup analyses were conducted to explore potential sources of heterogeneity. RESULTS Eleven original studies including 45,281 adolescents (49% boys) were reviewed. Compared to adolescents with lower levels of PA, adolescents with higher levels of PA had a 29% decreased risk of developing depression in adulthood (OR = 0.71, 95%CI = 0.59-0.86, P < 0.01; τ^2 = 0.07; I^2 = 86.0%). Notably, compared to those with a stable low level of PA, adolescents who increased their PA levels showed a 21% reduced risk of depression in adulthood (OR = 0.79, 95%CI = 0.68-0.92), while those who sustained high levels of PA experienced an even greater reduction (OR = 0.66, 95%CI = 0.54-0.81). Sensitivity analyses confirmed the robustness of findings. Subgroup analyses indicated that heterogeneity was primarily attributed to data source (Pinteraction = 0.04) and follow-up period (Pinteraction < 0.01). CONCLUSIONS Our systematic review and meta-analysis of prospective observational studies indicates that higher levels of PA during adolescence protect against depression in adulthood. These findings reinforce the importance of promoting PA during adolescence as a key focus of public policies to reduce mental health issues in later life.