Effect of Exercise on Brain-Derived Neurotrophic Factor in Stroke Survivors: A Systematic Review and Meta-Analysis

Background: BDNF (brain-derived neurotrophic factor) is a biomarker of neuroplasticity linked with better functional outcomes after stroke. Early evidence suggests that increased concentrations after exercise may be possible for people with stroke, however it is unclear how exercise parameters influence BDNF concentration. Methods: This systematic review and meta-analysis searched 7 electronic databases. Experimental or observational studies measuring changes in BDNF concentration after exercise in people poststroke were included. Data were extracted including characteristics of the study, participants, interventions, and outcomes. Several fixed and random effects meta-analyses were completed. Results: Seventeen studies including a total of 687 participants met the eligibility criteria (6 randomized trials). Significant improvements were observed in BDNF concentration following a single session (mean difference, 2.49 ng/mL; [95% CI, 1.10-3.88]) and program of high intensity aerobic exercise (mean difference, 3.42 ng/mL; [95% CI, 1.92-4.92]). Conclusions: High intensity aerobic exercise can increase circulating BDNF concentrations, which may contribute to increased neuroplasticity. Registration: URL: https://www.crd.york.ac.uk/PROSPERO/; Unique identifier: CRD42021251083.