Hearing Loss and Dementia: A Population-Based Cohort Study.

Introduction: Hearing loss (HL) is considered a potentially modifiable risk factor for dementia. We aimed to examine the relationship between HL and incident dementia diagnosis in a province-wide population-based cohort study with matched controls.

Methods: Administrative healthcare databases were linked to generate a cohort of patients who were aged ≥40 years at their first claimed hearing amplification devices (HAD) between April 2007 and March 2016 through the Assistive Devices Program (ADP) (257,285 with claims and 1,005,010 controls). The main outcome was incident dementia diagnosis, ascertained using validated algorithms. Dementia incidence was compared between cases and controls using Cox regression. Patient, disease, and other risk factors were examined.

Results: Dementia incidence rates (per 1,000 person-years) were 19.51 (95% confidence interval [CI]: 19.26-19.77) and 14.15 (95% CI: 14.04-14.26) for the ADP claimants and matched controls, respectively. In adjusted analyses, risk of dementia was higher in ADP claimants compared with controls (hazard ratio [HR]: 1.10 [95% CI: 1.09-1.12, p < 0.001]). Subgroup analyses showed a dose-response gradient, with risk of dementia higher among patients with bilateral HADs (HR: 1.12 [95% CI: 1.10-1.14, p < 0.001]), and an exposure-response gradient, with increasing risk over time from April 2007-March 2010 (HR: 1.03 [95% CI: 1.01-1.06, p = 0.014]), April 2010-March 2013 (HR: 1.12 [95% CI: 1.09-1.15, p < 0.001]), and April 2013-March 2016 (HR: 1.19 [95% CI: 1.16-1.23, p < 0.001]).

Conclusion: In this population-based study, adults with HL had an increased risk of being diagnosed with dementia. Given the implications of HL on dementia risk, understanding the effect of hearing interventions merits further investigation.