Study: Is There a Connection Between Hearing Loss and Dementia?

Hearing loss (HL) is linked to a higher risk of dementia among people aged 45 to 64, according to the researchers of a study published in JAMA Network Open.

In a population-based cohort study, researchers aggregated data on 16,270 participants from the National Health Insurance Research Database of Taiwan. The exposed HL group comprised patients newly diagnosed with HL from 2000 through 2011 (n = 8,135). Subsequently, the HL subjects were matched based on sex, age, residence, and insurance premium to individuals in a non-HL cohort (n = 8,135).  The researchers used multivariate Cox proportional hazards regression models adjusted for covariates to discern the association between HL and dementia. The first dementia diagnosis of each person within the study period was used to calculate the risk of dementia during specific time intervals. The risk of dementia during the follow-up period was calculated using survival analysis. Data were analyzed from January 2000 to December 2013.

The Need to Implement Early Hearing Protection

According to the results of the study, 16,270 participants (57% men; mean age, 65), developed dementia, and the dementia incidence rate in the HL group was higher compared to the non-HL group (19.38 [95% CI, 18.25 to 20.57] per 1,000 person-years juxtaposed to 13.98 [95% CI, 13.01 to 15.00] per 1,000 person-years) during the follow-up period. Moreover, in fully adjusted multivariate Cox proportional hazards regression models which adjusted for risk analysis, patients with HL showed a notable risk of dementia (HR=1.17; 95% CI, 1.07 to 1.29; false discovery rate [FDR] P = .003). Furthermore, subgroup analysis revealed that across three age groups (45-64, 65-74, and ≥75 years), the group aged 45 to 64 years was associated with the highest risk of dementia (HR=2.21; 95% CI, 1.57 to 3.12]; FDR P < .001).

In noting limitations of the study, the researchers wrote that the “principal (limitation) with any study of this nature is that causality is difficult to infer, and we can only state that findings support a given hypothesis. In addition, the main limitation of studies based on the insurance database is the lack of precision in dementia diagnosis.” They added that “the database contains limited or no information on other potential confounders such as educational level, body mass index, physical activities, diet pattern, blood pressure, blood glucose levels, smoking, and use of hearing aids. Information on dementia subtype and HL severity is also lacking in the study database. Disease onset and diagnosis may differ according to the economic status and residence of patients because these variables affect access to neurologists.”

In conclusion, the study authors wrote that the results of this study “suggests that the implementation of early hearing protection, HL screening, and the use of hearing aids may help to mitigate this potential risk factor for dementia.”