Do self-reported hearing and visual impairments predict longitudinal dementia in older adults?

Background: Sensory impairments have been associated with dementia in older adults. However, the contribution of different impairments and how they interact in the development of dementia is not clear. We examined the independent and interaction effects of hearing impairment (HI) and visual impairment (VI) on incident dementia.

Design: Multi-centric population-based prospective cohort study.

Setting: Data were taken from the AgeDifferent.de platform, pooling participants aged 75 and older from the German LEILA75+ and AgeCoDe/AgeQualiDe cohorts.

Participants: Older adults (N = 3497) with mean age 79.8 years, 67.2% female.

Measurements: Standardized interviews and questionnaires were used to assess self-reported HI and VI at baseline and all-cause dementia in 9 follow-ups, spanning over 20 years.

Methods: Competing risk regression models were conducted to test the main and interaction effects of HI and VI on dementia incidence, adjusting for established risk factors of dementia and accumulated mortality.

Results: HI and VI at baseline were reported by 30.3% and 16.6% of individuals, respectively. Adjusting for baseline information on sociodemographics, substance use, cognitive functioning and morbidity, and controlling for accumulated mortality risk, HI (sHR 1.16, 95% CI 1.04-1.30, p = 0.011) but not VI (sHR 1.07, 95% CI 0.90-1.28, p = 0.462) was significantly associated with incident dementia. There was no interaction between HI and VI (sHR 1.09, 95% CI 0.81-1.46, p = 0.567).

Conclusions: Hearing impairment is associated with an increased incidence of all-cause dementia in older adults. There is no excess risk or risk compensation through the additional presence or absence of visual impairment. Early prevention measures for hearing impairment might help to reduce the long-term risk of dementia.