Making Sense of Brain Aging: Hearing and Visual Impairments, Ophthalmic Conditions, and Risk of Dementia in Older Adults

Phillip Hwang | 2020

Advisor: Annette L. Fitzpatrick

Research Area(s): Aging & Neurodegenerative Diseases, Clinical Epidemiology

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Background: Hearing and vision play an important role in physical, mental, and functional health. Less is known about the impact of deficits in hearing and vision, including dual sensory impairment (DSI), and causes of these sensory impairments on cognitive function. Objectives of this study were to examine risk of dementia associated with: (1) hearing and visual impairments in late-life; and (2) common ophthalmic conditions in older adults, such as cataracts, age-related macular degeneration (AMD), diabetic retinopathy (DR), and glaucoma.

Methods: Participants from the Ginkgo Evaluation of Memory (GEM) Study and the Cardiovascular Health Study (CHS) who were dementia-free at baseline were included in the analyses. Information on hearing and visual impairments were based on self-report at baseline in the GEM Study and CHS. Additionally, in CHS, data on hearing and vision were collected at multiple follow-up visits. Medical histories collected by CHS and ICD-9 diagnostic codes from Medicare Part B claims data were used to ascertain diagnoses of specific ophthalmic conditions. Incident dementia, including major subtypes of Alzheimer’s disease (AD) and vascular dementia (VaD), was adjudicated by a consensus committee using standardized criteria. Multivariable Cox models were used to estimate risk of dementia, presented as hazard ratios (HRs) and 95% confidence intervals (CIs).

Results: Greater number of sensory impairments was associated with increased risk of dementia in a graded fashion in both the GEM Study (P = 0.002) and CHS (P <0.001). DSI at baseline was associated with increased risk for all-cause dementia (HR = 1.86; 95% CI = 1.25 – 2.76) and AD (HR = 2.12; 95% CI = 1.34 – 3.36) in the GEM Study. Time-varying DSI was also associated with increased risk for all-cause dementia (HR = 2.60; 95% CI = 1.66 – 4.06) and AD (HR = 3.67; 95% CI = 2.04 – 6.60) in CHS. DSI severity at baseline in the GEM Study was associated with risk for all-cause dementia in a dose-dependent fashion (P = 0.02). Longer duration of DSI was associated with increased risk for all-cause dementia in CHS (P = 0.02). In CHS, increased risk for AD was associated with AMD (HR = 1.87; 95% CI = 1.13 – 3.09) and cataracts (HR = 1.34; 95% CI = 1.01 – 1.80). Increased risk for VaD was associated with DR (HR = 2.63; 95% CI = 1.10 – 6.27) and cataracts (HR = 1.41; 95% CI = 1.02 – 1.95).

Conclusions: Older adults with hearing and visual impairments are at elevated risk of developing dementia. Differential associations between cataracts, AMD, DR, and incident dementia may reflect heterogeneous underlying neurodegenerative and vascular pathways shared between the eye and brain. Evaluation of hearing and vision, including common ophthalmic conditions associated with vision loss, may represent important areas for interventions in older adults to promote healthy cognitive aging.