The Effects of Exercise on BDNF Levels in Adolescents: A Systematic Review with Meta-Analysis.

The aim of this study was to analyze the evidence available in the literature about the effects of exercise on brain-derived neurotrophic factor levels in adolescents. The literature searches were conducted in PubMed, Embase, Scopus, ScienceDirect, Web of Science, SportDiscus, the Cochrane Central Register of Controlled Trials (CENTRAL) and CINAHL. Randomized controlled trials and non-randomized controlled trials performed with adolescents (10-19 years) who underwent different exercise programs and who evaluated BDNF levels before and after the intervention were included. We included six studies, four RCTs and two non-RCTs in the systematic review with a total of 407 adolescents. In two randomized trials and one non-RCT, the intervention groups showed significant improvements in BDNF levels compared with the control group. The results presented in the meta-analysis indicate that despite the positive effect in favor of the intervention, there were no significant differences (standardized mean difference 0.28 ng/mL, 95% confidence interval -0.28 to 0.85; p = 0.32, I² = 0%). The results presented in our review indicate that aerobic exercise programs practiced in moderate- or high-intensity are promising strategies to increase BDNF levels in adolescents. However, further studies are required to support this finding.

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.

Protocol for systematic reviews of school-based food and nutrition education intervention for adolescent health promotion: Evidence mapping and syntheses.

BACKGROUND: Nutrition is an important modifiable factor in combating overweight and obesity among adolescents. School has been indicated as an effective environment for influencing eating behavior; however, recent reviews assessing school-based interventions specifically for adolescents are scarce. Therefore, we propose the present systematic review with the aim to comprehensively review the quantitative and qualitative literature on the effects of school-based food and nutrition education interventions on adolescent health promotion through healthy eating habits. METHODS: We will search MEDLINE/PubMed, Embase, Scopus, ERIC, ScienceDirect, Web of Science, Cochrane, LILACS, and ADOLEC. We will include randomized controlled trials (RCT), non-RCT, and controlled before-after studies. Risk of bias will be assessed using the EPOC Risk of Bias Tool for RCT, Risk of Bias in Non-randomized Studies of Interventions (ROBINS-I) tool for non-RCT or controlled before-after, as well as the Critical Appraisal Skills Program (CASP) checklist for qualitative studies. We will analyze the overall strength of the evidence for each outcome using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) tool. Two independent researchers will conduct all evaluations and any disagreements will be consulted with a third reviewer. Data analysis and synthesis will be analyzed by the RevMan 5.3 software. We will conduct the study in accordance with the guideline of the Preferred Reporting Items for Systematic Review and Meta-analyses Protocols. RESULT: This review will evaluate the effects of school-based food and nutrition education interventions on adolescent health promotion through healthy eating habits. The primary outcome will be changes in adolescent food consumption. Secondary outcomes will be biological parameters (e.g., body mass index (BMI), waist circumference (WC), body composition, etc); biochemical parameters (e.g., glycemia, triglycerides, total cholesterol, etc); qualitative evidences that support or explain the effect of school-based food and nutrition education interventions on adolescent food consumption. CONCLUSION: The findings of this systematic review will summarize the latest evidence of the effects of school-based food and nutrition education interventions on adolescent health promotion. The findings will be an available reference for school-based interventions and other further research. REGISTRATION: PROSPERO CRD42019116520.