Moreover, joint and meta-analyses including individuals from six studies across four different populations Mexicans, Mexican Americans, Peruvians, Bolivians, and Caribbean Hispanics found a nominally significant protective effect of the APOE-ε2 allele against the risk of Alzheimer’s disease and related disorders [43], which may help explain the low prevalence of NCD observed in our study. This evidence concerns the gene APOE and early-onset autosomal dominant Alzheimer disease.