The Risk of Dementia Following Hearing Disorder Onset: A National Cohort Study

Objectives: This study aimed to examine the association between all-cause hearing disorder onset and dementia risk, owing to prior reports of inconsistencies and untested potential biases. Design: National cohort study. Setting and Participants: All members of an Israeli nonprofit health maintenance organization aged 51–71 years without hearing disorder or dementia diagnoses at cohort entry were followed up to 17.2 years for incident dementia. At cohort entry, there were 102,067 participants (mean age 57.8, SD = 5.7 years; female: 53,242, 52.2%). Methods: Hearing disorder was a time-varying covariate classified as present from the age of the first diagnosis onward, otherwise absent. Cox regression models were fit to quantify all-cause dementia risk with hazard ratios (HR) and their 95% confidence intervals (CIs) in the primary analysis, applying inverse probability weights, adjusted for 20 potential sources of confounding. Results: During follow-up, incident all-cause hearing disorder onset was 50,769 (49.7%) and dementia 6612 (6.5%). Dementia was observed among 4506 (8.9%) individuals with a hearing disorder and 2106 (4.11%) without. In the primary analysis, hearing disorder onset was statistically significantly (P < .05) associated with an increase of all-cause dementia risk (adjusted HR, 1.91; 95% CI, 1.79–2.03). Of 15 complementary analyses, 10 were consistent with the primary analysis, 2 showed that hearing aid and/or assistive listening device use was associated with reduced dementia risk, and 3, although significant, showed moderate reverse causation. Conclusions and Implications: In this study, hearing disorder onset was associated with increased dementia risk. Policymakers, patients, and clinicians may wish to monitor hearing disorders to consider possible preventive dementia measures with hearing aids and/or assistive listening devices.