Association between apolipoprotein E gene polymorphisms and serum lipid indicators and Alzheimer's disease risk

Background Apolipoprotein E ( APOE ) polymorphisms, particularly the APOE4 genotype, are established genetic risk factors for Alzheimer's disease (AD). However, the clinical utility of combining APOE genotypes with serum lipids and blood-based AD biomarkers remains incompletely defined. Objective To investigate the association between APOE gene polymorphisms, serological indicators, and the occurrence of AD. Methods Blood samples of 109 patients with AD and 85 non-AD participants were used to detect APOE genotypes. Serum levels of total cholesterol (TC), triglyceride (TG), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), amyloid-β 1–42 (Aβ 1–42 ), and p-tau-181 were measured. Receiver operating characteristic analysis was performed in an independent validation set of 82 cases. Results The frequency of the APOE4 genotype was significantly higher in the AD group compared with the non-AD group, whereas APOE2 and APOE3 genotypes showed no significant differences. TC, HDL-C, and LDL-C levels were significantly elevated in the AD group compared with the non-AD group, while TG, Aβ 1–42 , and p-tau-181 levels did not differ significantly. Among patients with AD carrying the APOE4 genotype, TC and LDL-C levels were significantly higher than those in non-AD APOE4 carriers. Further, within the AD group, APOE4 carriers had a significantly higher proportion of elevated TC and LDL-C levels than non- APOE4 carriers. Validation experiments revealed that the combination of APOE4 genotype with elevated TC and LDL-C demonstrated greater diagnostic efficacy for AD. Conclusions APOE4 genotype combined with elevated TC and LDL-C levels strongly correlate with AD onset and may be valuable auxiliary biomarkers for AD diagnosis and treatment.