Association between cognitive function and plasma lipids of the elderly after controlling for apolipoprotein E genotype.

OBJECTIVE Although the relationship between cognitive function and plasma lipids has attracted attention, previous studies have shown conflicting results. One possible confounding factor is due to the influence of gene-related modulator. We investigated the relationship between cognitive function and lipid plasma levels of old age after controlling for apolipoprotein E (APOE) genotype. METHODS One thousand three hundred ninety-five subjects without dementia age 65 and older participated in this study. They were divided into two groups, with and without APOE4 [E4 (+) and E4 (-)]. Plasma concentrations of high-density lipoprotein (HDL), low-density lipoprotein (LDL), triglyceride (TG), total cholesterol (TC) and apolipoprotein E (apoE) were measured. Associations between plasma concentrations of lipids and cognitive function were investigated for each group. RESULTS We found a positive association between cognitive scores and plasma apoE level in both E4 (-) and E4 (+) groups. A positive relationship was also observed between cognitive score and HDL level in the E4 (-) group, but not in the E4 (+) group. No substantial association between cognitive score and LDL, TG, and TC levels was found in either of the groups. CONCLUSIONS Our findings suggest that plasma apoE have a positive influence on cognitive function in both E4 (-) and E4 (+) groups, whereas the positive influence of plasma HDL was shown only in E4 (-) group. The identification of the influences of (APOE) genotype and the intracellular linkage among apoE and HDL metabolism is hoped for new preventive and therapeutic strategies for cognitive change of elderly.