We also estimated a causal effect of Alzheimer’s risk on weight change (bxy = −0.034, s.e. 0.005, P = 2.3 × 10−10, based on 64 AD-associated SNPs), but this result was dependent on the many SNP located on chromosome 19 (i.e., near the APOE locus). This evidence concerns the gene APOE and Alzheimer disease.