Hearing Loss and Dementia Prevalence Across Countries: Global Ecological Evidence in Females and Males

Background: Hearing loss is a well-established modifiable risk factor for dementia at the individual level, but less is known about whether hearing loss prevalence aligns with dementia prevalence at the country level across diverse socioeconomic and demographic contexts. This study examined sex-stratified country-level associations between hearing loss prevalence and dementia prevalence, while avoiding causal interpretation of ecological associations. Methods: Country-level sex-specific prevalence estimates for hearing loss and dementia prevalence were obtained from the Global Burden of Disease data resources. Analyses were conducted separately for females and males and included descriptive sample summaries, Pearson and Spearman correlations, principal component analysis, partial correlations used as sequential robustness checks, and theory-informed multivariable linear regression. Variables were log10-transformed for the primary analyses. Models adjusted for economic development, urbanisation, the Henneberg Index, and sex-specific life expectancy at age 60. Formal sex comparison was evaluated using coefficient-comparison testing of the hearing-loss effect from comparable adjusted models. Results: The global bivariate association between hearing loss prevalence and dementia prevalence was strong in females (Pearson r = 0.827; Spearman rho = 0.845; p < 0.001) and males (Pearson r = 0.848; Spearman rho = 0.855; p < 0.001). Principal component analyses indicated that hearing loss prevalence clustered with socioeconomic and demographic indicators in both sexes, explaining more than 70% of total variance. In multivariable regression models, adding hearing loss increased explanatory power in females (R² from 0.661 to 0.827) and males (R² from 0.674 to 0.811). A formal coefficient-comparison test did not indicate a statistically meaningful difference between the female and male hearing-loss coefficients in the fully adjusted models (z = 0.82; p = 0.41). Conclusions: Hearing loss prevalence is strongly associated with dementia prevalence at the country level in both females and males after adjustment for macro-level socioeconomic and demographic covariates. The findings support the population-level relevance of hearing health for dementia surveillance and prevention, while indicating broad convergence rather than clear sex-based divergence in the hearing loss-dementia association.