Association of exercise, brain-derived neurotrophic factor, and cognition among older women: A systematic review and meta-analysis

This systematic review and meta-analysis explored the effects of structured exercise regimens on brain-derived neurotrophic factor (BDNF) levels, a proxy for cognitive function, in older women. In this study, we collated evidence from the available clinical trials that reported BDNF levels and other outcomes following structured exercise regimens. Adhering to PRISMA Statement 2020 guidelines. PubMed/MEDLINE, Scopus, CINAHL Plus, and Cochrane were systematically searched using a combination of the following keywords: brain-derived neurotrophic factor, women, exercise, older, cognition, and/or cognitive. A random-effects model was applied; the statistical analysis was conducted in RevMan 5.4 (Cochrane). The risk of bias in the included trials was assessed using the Risk of Bias in Non-Randomized Studies of Interventions (ROBINS-I) tool. Across 12 trials, 994 older women were included that were enrolled in different exercise regimens globally. Exercise regimens were categorized as aerobic, resistance/power training, aquatic, taekwondo, and multimodal and ranging from 30 to 60 min, 1-5 times per week across 5-24 weeks. Moderate improvement (Cohen\u27s d: 0.44, 95% CI: 0.04-0.84, p = 0.03) was found in BDNF levels across all trials. There was a small yet insignificant improvement in mini-mental state examination (MMSE) scores (Cohen\u27s d: 0.17, 95% CI: -0.79-1.13, p = 0.73). Aerobic exercise, aquatic exercise, and multimodal regimens showed significant association with improved BDNF levels but the sample size for individual exercise regimens was small A main limitation was the inclusion of 114 (10.3%) males in the data, introducing gender bias. This study provides novel insight into the association between various exercise regimens and BDNF levels among older women