2.1. Sample Size Analysis
The sample size calculation was carried out by G*Power 3. The goal of this study was to find a relationship between BDNF and cognitive functions with a medium effect size (f = 0.2526456) based on partial eta-squared 0.06. Using the analysis of variance (ANOVA) for repeated measures within factors, setting the α-error to 0.05, the power to 80%, and 2 groups, the minimal sample size was estimated at 34. For this trial, a total of 20 participants were enlisted, accounting for a dropout rate of 10% [