Age-related hearing loss and dementia risk causality: two-way Mendelian randomization analysis

Abstract In response to the ongoing debate in clinical studies about the relationship between age-related hearing impairment and dementia, a two-sample Mendelian randomization (MR) study using a genome-wide association study (GWAS) database was conducted to elucidate the genetic effects of age-related hearing loss on four types of dementia (dementia, vascular dementia, and Parkinson's dementia，Alzheimer's disease).MR analyzed data from two independent sources on age-related hearing loss (exposure) and four dementias (outcome). We used the inverse variance weighting (IVW) method, the MR Egger method, and the weighted median (WM) method to investigate the impact of age-related hearing loss on dementia.In addition, we analyzed heterogeneity, horizontal diversity, and stability through Cochran's Q-test, MR-Egger intercept, and leave-one-out sensitivity analysis, respectively.Age-related hearing loss was associated with dementia (OR=1.054, 95% CI:0.633-1.754, P=0.840), vascular dementia (OR=1.985, 95% CI:0.550-7.169), P=0.295), Parkinson's dementia (OR=2.263, 95% CI:0.235-21.774, P=0.480), andAlzheimer's disease (OR=1.001, 95% CI:0.999-1.004, P=0.392), but no causal effect was found.The results of our study indicate that there is no statistically significant responsible association between age-related hearing loss and any of the four dementias, in accordance to our two-sample MR analysis.