BDNF and Alzheimer disease: The analysis of 12 studies (n = 1066) [28,35,36,37,38,39,40,41,42,46,48,55] showed that HM combined with AD significantly increased concentrations of BDNF compared to ADs alone (SMD = 1.38, 95% CI: 0.92–1.83, p < 0.00001, I2 = 91%) (Figure 6).