Hearing Loss as a Risk Factor for Dementia: A Nationwide 15-Year Follow-Up Cohort Study in Taiwan

Introduction: Although hearing loss is associated with dementia, the exact causal relationship between hearing loss and dementia remains unclear. Early detection and prevention of hearing loss are essential. In this study, data from the National Health Insurance Research Database (NHIRD) of Taiwan were used to monitor patients with hearing loss for 15 years to determine whether hearing loss leads to dementia. Methods: This retrospective matched-cohort study involved 208,570 individuals, divided into 41,714 patients with hearing loss and 166,856 controls matched by sex, age, and chronic diseases. Cox regression analysis was conducted on data obtained from the NHIRD for the period 2000-2015 to determine the hazard ratio (HR) associated with dementia. Results: The percentage of patients with hearing loss who developed dementia was higher than that of the control group (18.67% vs. 14.10%). The onset age of dementia was younger in the hearing loss group (69.95 vs. 70.31 years, p = 0.001). Middle-aged individuals (45-65 years) with hearing loss were more likely to develop dementia compared with those without hearing loss (48.53% vs. 47.94%, p = 0.03). Compared with the controls, the patients with hearing loss were more likely to develop hyperlipidemia and stroke. In the patients with hearing loss, the adjusted HRs for Alzheimer's disease (AD), vascular dementia, and other types of dementia were significant. The patients were followed up for an average of 7.82 years. Compared with the controls, the patients with hearing loss exhibited a shorter mean time to dementia onset (5.21 vs. 5.49 years, p < 0.001). Conclusion: Hearing loss may increase the risks of AD, dementia, hyperlipidemia, and stroke. Therefore, health-care providers should closely monitor cardiovascular complications in patients with hearing loss.