The biphasic impact of apolipoprotein E ε4 allele on age-related hearing loss

Both the ε4 variant of the apolipoprotein E (APOE) gene and hearing loss are well-known risk factors for Alzheimer's disease. However, previous studies have produced inconsistent findings regarding the association between APOE genotypes and hearing levels, necessitating further investigation. The aim of this study was to investigate the relationship between APOE genotypes and hearing levels. This retrospective study analyzed clinical data from a clinical data warehouse of seven affiliated Catholic Medical Center hospitals. The study included 1,162 participants with records of APOE genotypes, audiometric tests, and cognitive function tests. In Generalized linear mixed model analysis, ε4 carriers exhibited lower pure tone audiometry thresholds with an estimate of -0.353 (SE = 0.126, p = 0.005). However, the interaction term for age and APOE ε4 had a coefficient of 0.577 (SE = 0.214 p = 0.006), suggesting that the APOE ε4 gene may accelerate hearing deterioration with age. Subgroup analysis based on an age cut-off of 75 revealed that ε4 carriers had better hearing at younger ages, but showed no significant difference at older ages. These results indicate that the ε4 allele may have a biphasic effect on hearing levels depending on age.