Unveiling the link between APOE ε4, environmental factors, and Alzheimer's disease in North Lebanon: A case-control study

Background Alzheimer's disease (AD) is a multifactorial and progressive neurodegenerative disorder influenced by a variety of genetic and environmental factors. The apolipoprotein E (APOE) gene is known to have a pivotal impact on disease onset, yet clinical studies on its impact on AD remain scarce in Lebanon. Objective This study investigates the interplay between environmental risk factors, the APOE gene, and AD in North Lebanon. Methods A case-control study was conducted with 136 individuals, including 57 AD patients and 79 normal individuals, among which 55 individuals were verified to be cognitively normal via the Mini-Mental State Examination (MMSE). A comprehensive survey was used to collect data on lifestyle factors, medical history, and other possible diseases and deficiencies. Blood samples were collected from all participants, then their DNA was isolated and stored. Real-time PCR was adopted for genotyping. Results The total APOE epsilon 4 allele prevalence was reduced from 19.1% to 16.1% after MMSE adjustment. Based on the univariate analysis, factors like age, illiteracy, vitamin and iron deficiencies, blood pressure, and chronic diseases were identified as prominent risk factors, while the allele showed no significant correlation with AD. However, in the multivariable analysis, this allele emerged as a key risk factor (p = 0.04). Factors like age >= 65, vitamin deficiency, iron deficiency, blood pressure, and other chronic diseases were consistently significant. Conclusions Our results provide significant evidence that the influence of APOE epsilon 4 on AD is governed by several environmental factors such as age, vitamin and iron deficiencies, high blood pressure, and chronic diseases.