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

•Investigated the impact of exercise on cognitive function and the role of brain-derived neurotrophic factor (BDNF) as a promising biomarker in older women (aged 60 and over) across 12 clinical trials.•Noted varied study settings, with half conducted in communities and three in healthcare environments.•Focused on primarily female participants over 60, with normal/mildly impaired cognitive function and sedentary lifestyles.•Indicated that exercise regimens, irrespective of type, positively affected cognitive function in older women, as evidenced by enhanced BDNF levels and improved cognitive test performance.•Highlighted the importance of promoting healthy aging and identifying potential strategies for maintaining cognitive function in older adults. 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's 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's 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 exerci