Dual sensory impairment is linked with an increased risk for dementia, specifically Alzheimer disease (AD), according study findings published in JAMA Network Open.

Current estimates predict that more than 13 million Americans may have dementia by 2050, and researchers are seeking to identify modifiable risk factors to address that upcoming challenge. The researchers of the current study previously found that all-cause dementia and Alzheimer disease (AD) are linked with dual sensory impairment (hearing and visual impairments) among older adults. Studies have indicated the deficits could have similar pathophysiology and lead to dementia through increasing isolation and depression and decreasing physical activity and compensatory mechanisms. Yet, the studies only measure hearing and vision 1 time at baseline.

The objective of the current study was to analyze dual sensory impairment association with incident dementia in the Cardiovascular Health Study (CHS).


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In the CHS Cognition Study, researchers from 1992 to 1999 analyzed data from 2927 patients aged mean 74.6±4.8 years (58.2% women; 85.5% White, 15.5% Black) with Medicare in 4 US communities with academic medical centers who did not have dementia at baseline. Participants reported any hearing or vision impairments at all study visits. The researchers analyzed the associations of sensory impairments and dementia with time-dependent Cox regression models.

During follow-up, 10.5% of individuals developed dementia. Four percent of individuals developed dual sensory impairment, while 12.4% developed visual impairment only, and 10.6% of individuals developed hearing impairment only.

Adjusted for baseline covariates, dual sensory impairment was 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). The associations of 1 sensory impairment with all-cause dementia (HR, 1.72; 95% CI, 1.34-2.21) and with AD (HR, 2.32; 95% CI, 1.63-3.29) were not as strong as the dual sensory impairment associations. Vascular dementia (VaD) was not associated with dual sensory impairment compared with no sensory impairment.

The researchers found similar results when they solely analyzed cognitive healthy individuals, incorporated a 1-year lag period for dementia onset, and evaluated data of multiple imputation using chained equations (MICE).

Hearing and vision loss were each independently associated with increased risk of all-cause dementia. Hearing impairment was associated with VaD (HR, 1.66; 95% CI, 1.16-2.38).

Individuals with more than 2 years of dual sensory impairment had a greater risk for all-cause dementia (HR, 1.61; 95% CI, 1.04-2.53) and nearly double the risk (HR, 1.96; 95% CI, 1.11-3.50) for AD compared with individuals without dual sensory impairment. Risk increased 31% for all-cause dementia and 46% for AD per year with dual sensory impairment.

Study limitations included unknown accuracy of questions assessing hearing and visual function in CHS, possible misclassification of dementia, and generalization outside individuals aged at least 65 years without dementia.

“With the public health burden of dementia expected to increase in the coming decades, our findings suggest that evaluation of vision and hearing should play an important role in preventive strategies for dementia,” the researchers concluded.

Reference

Hwang PH, Longstreth WT Jr, Thielke SM, et al. Longitudinal changes in hearing and visual impairments in older adults in the United States. JAMA Network Open. Published online May 5, 2022. doi: 10.1001/jamanetworkopen.2022.10734