When the data from Salehi et al were included in the analysis, it led to a pooled weighted mean difference with a random effects model of 20.58 ng/mL (95%CI: [-5.17, 46.32]; I2 = 98%; Cochran’s Q = 1433.16; P<0.00001) in favor of greater IGF-1 in AD, however there was no overall effect of Z = 1.57; p = 0.12. This evidence concerns the gene IGF1 and Alzheimer disease.