A population-based cohort study found that increased levels of LDL-cholesterol were associated with increased risk of AD in ApoE4 non-carriers but not in ApoE4 carriers [34], and another cohort study showed that higher LDL-cholesterol was associated with decreased verbal memory in ApoE4 non-carriers but not in ApoE4 carriers [35]. This evidence concerns the gene APOE and Alzheimer disease.