Hearing loss and the risk of dementia: A longitudinal analysis of the Korean National Health Insurance Service Senior Cohort.

Abstract

Background: Hearing loss is a potentially modifiable risk factor implicated in dementia, with recent research suggesting an association between age-related hearing degradation and dementia.

Objective: This study aims to elucidate the relationship between hearing decline and dementia risk.

Methods: We analyzed data from 511,953 subjects from the Korean National Health Insurance Service-Senior Cohort (2002-2008). After excluding those diagnosed with dementia in 2002, 511,935 subjects were included. Subjects with hearing loss between 2002 and 2008 were selected and matched with a control group without hearing impairment based on age and gender. Statistical analyses, including Pearson's chi-squared test and the Cox proportional hazards model, were conducted, controlling for confounding variables such as household income and residential area. Subgroup analysis was also performed for Alzheimer's disease and vascular dementia.

Results: Subjects with hearing loss had a 1.245 times higher risk of all-cause dementia compared to those without hearing loss (adjusted hazard ratio over 3 years, 95% CI = 1.201-1.290), adjusting for gender, age, residence, and income. The adjusted hazard ratios for Alzheimer's disease over 3, 5, 7, and 10 years from the index date were 1.259 (95% CI = 1.211-1.308), 1.258 (95% CI = 1.208-1.310), 1.269 (95% CI = 1.215-1.325), and 1.235 (95% CI = 1.170-1.304), respectively. No significant association was found for vascular dementia, except for 3 years.

Conclusions: Hearing loss consistently increased the risk of all-cause dementia and Alzheimer's disease across timespans, suggesting a complex link between hearing loss and neurodegenerative diseases. These findings highlight the importance of early intervention and cognitive monitoring for individuals with hearing loss.