Effects of exercise on the levels of BDNF and executive function in adolescents: A protocol for systematic review and meta-analysis

BACKOGROUND: Evidence available in the literature suggests that physical exercise increases the release of brain-derived neurotrophic factor (BDNF) in humans and may possibly be related to improvements in executive function. However, studies of this phenomenon in adolescents are still scarce. The objective of this work is to describe the protocol for a systematic review (SR) and meta-analysis of interventional studies aiming to determine the effect of physical exercise on BDNF levels and executive function in adolescents. METHODS: This protocol is guided by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Protocols (PRISMA-P) and by the Cochrane Handbook of Systematic Reviews of Interventions. The databases to be searched are PubMed, EMBASE, Scopus, ScienceDirect, Web of Science, SPORTDiscus, the Cochrane Central Register of Controlled Trials (CENTRAL), and CINAHL. Interventional studies conducted on adolescents with different exercise protocols and evaluations of BDNF levels and executive function in pre- and post-intervention periods will be included in the systematic review. The characteristics of the studies, participants, and main results will be described, then the evaluation of the risk of biases and the level of evidence obtained by the protocol will be assessed. The selection of studies, data extraction, and evaluation of the methodological quality will be performed by 2 experienced reviewers independently. CONCLUSION: The systematic review will present the effects of the practice of physical exercises on the BDNF and executive function levels. The results will strengthen the interventions with the focus on the brain health of adolescents through general orientations and the evidences described shall direct future research. PROSPERO REGISTRATION NUMBER: CRD42018110683