Examining the Combined Estimated Effects of Hearing Loss and Depressive Symptoms on Risk of Cognitive Decline and Incident Dementia

Objectives: Late-life depression is a comorbidity that may co-occur in older adults with hearing loss - each has prevalent and independent modifiable risk factors for dementia. Methods: Using data from 1,820 Health, Aging and Body Composition study participants (74 ± 2.8 years, 38% Black race), we compared the hearing loss-dementia/cognitive decline relationship between those with normal hearing/mild hearing loss and those with moderate or greater hearing loss. Using linear mixed-effects and Cox proportional hazard models, we investigated if the associations between hearing loss and cognitive decline or dementia (Modified Mini-Mental State [3MS] Examination and Digit Symbol Substitution Test [DSST]) differed by the presence or absence of depressive symptoms. Depressive symptoms were defined as Center for Epidemiologic Study - Depression scale 10 ≥10 at one or more visits from Years 1-5. Algorithmic incident dementia was defined using medication use, hospitalizations, and cognitive test scores. Audiometric hearing loss was measured at Year 5 and categorized as normal/mild versus moderate or greater hearing loss. Results: Having both hearing loss and depressive symptoms (vs. having neither) was associated with faster rates of decline in 3MS Examination (β = -0.30; 95% confidence interval [CI]: -0.78, -0.19) and DSST (β = -0.35; 95% CI: -0.67, -0.03) over 10 years of follow-up. Having both hearing loss and depressive symptoms (vs. neither) was associated with increased risk (hazard ratio [HR]: 2.91; 95% CI: 1.59, 5.33 vs. HR: 1.54; 95% CI: 1.10, 2.15 hearing loss only and HR: 2.35; 95% CI: 1.56, 3.53 depressive symptoms only) of incident dementia in multivariable-adjusted Cox proportional hazards models. Discussion: Comorbid conditions among hearing-impaired older adults should be considered and may aid in dementia prevention and management strategies.