Hearing loss and the risk of dementia in later life.

Dementia is a major source of disability worldwide and there are currently no available disease-modifying treatments. Hearing loss may be associated with increased risk of dementia in later life and therefore could be a modifiable risk factor, given the availability of efficacious interventions. We investigated the association of hearing loss and dementia through two complementary approaches: a prospective, cohort study of 37,898 older men (mean age 72.5 ± 4.6 years) with a mean follow-up of 11.1 years, and a systematic review and meta-analysis of prospective studies. In our cohort, men with hearing loss were more likely to develop dementia (n = 6948, 18.3%) than men free of significant hearing impairment - adjusted hazard ratio 1.69, 95% CI = 1.54-1.85. In our review, the aggregated hazard of dementia was 1.49 (95% CI 1.30-1.67) in those with hearing impairment (14 included studies). Study quality, duration and dementia type did not alter the results considerably. We found an increased risk of incident dementia with hearing impairment in both our novel data and the meta-analysis. This is an important finding, particularly in light of recent suggestions that mid-life hearing loss may account for up to 9.1% of dementia cases worldwide, and efforts to reduce its impact should continue to be explored.