ACTIVE BODY, IMPROVED BRAIN: EFFECTS OF EXERCISE INTERVENTIONS ON BDNF LEVELS ACROSS THE LIFESPAN - SYSTEMATIC-REVIEW AND META-ANALYSIS OF RANDOMIZED CONTROLLED TRIALS WITH MODERATOR ANALYSES

Objective: To assess the effects of exercise on brain-derived neurotrophic factor (BDNF) levels across the lifespan in apparently healthy children, adolescents, adults, and older adults and explore potential non-exercise-related and exercise-related moderators. Methods: We searched databases until Nov 22, 2023, for RCTs involving apparently healthy children, adolescents, adults, and older adults, evaluating the effect of exercise on BDNF levels. Multilevel meta-analyses used Hedges’s effect size. The primary aim was to determine the overall and age-group effects of exercise on BDNF. The secondary aim examined potential non-exercise-related and exercise-related moderators through meta-regression and subgroup analyses. This study was registered with PROSPERO, CRD42020191475. Results: Sixty-two articles comprising 106 effect sizes and 2,265 participants were included in this meta-analysis. The overall effect was of moderate magnitude (0.55, 95%CI: 0.42-0.68), as well as for children/adolescents (0.55, 95%CI: 0.12-0.97), adults (0.62, 95%CI: 0.47-0.76), and older adults (0.52, 95%CI: 0.22-0.81). Several factors moderated effectiveness of exercise intervention on BDNF, such as participant body mass index, BDNF source (serum vs. plasma), methodological quality of the studies, and exercise features (mode, intensity, and intervention duration). Conclusion: Exercise interventions are effective at increasing BDNF levels throughout the entire lifespan; however, their effectiveness can be moderated by both participant and exercise intervention characteristics. The findings of this study offer valuable insights into refining exercise prescription strategies, with a specific focus on BDNF as an outcome, to promote brain health.