Specifically, apolipoprotein (apo)A-I, the major HDL-associated protein, positively correlates with cognitive scores [20] and high serum HDL-cholesterol (> 55 mg/dl) in cognitively normal elderly individuals associates with reduced AD risk (hazard ratio (HR) 0.4) after adjusting for APOE genotype and vascular risk factors [21]. Here, APOE is linked to Alzheimer disease.