Summary: A recent study suggests a significant link between vision problems and dementia in older adults. The study examined nearly 3,000 elderly individuals, showing a higher risk of dementia among those with eyesight issues.
This data bolsters an increasing volume of research highlighting the correlation between vision and cognitive disorders. The team’s findings suggest that prioritizing vision health could be a key strategy in mitigating cognitive decline and reducing dementia risk.
Key Facts:
- The study showed that 22% of participants with impaired vision for seeing up close had dementia, and 33% of those with moderate or severe distance vision impairment had signs of dementia.
- After adjusting for other health differences, people with moderate to severe distance vision issues were 72% more likely than those with no vision issues to have dementia.
- The researchers’ previous work suggested that 1.8 percent of all dementia cases, more than 100,000 of the 6 million Americans with dementia, are likely related to vision loss.
Source: University of Michigan
Losing the ability to see clearly, and losing the ability to think or remember clearly, are two of the most dreaded, and preventable, health issues associated with getting older.
Now, a new study lends further weight to the idea that vision problems and dementia are linked.
In a sample of nearly 3,000 older adults who took vision tests and cognitive tests during home visits, the risk of dementia was much higher among those with eyesight problems – including those who weren’t able to see well even when they were wearing their usual eyeglasses or contact lenses.
The research was published recently in JAMA Ophthalmology by a team from the Kellogg Eye Center at Michigan Medicine, the University of Michigan’s academic medical center.
Based on data from a nationally representative study of older adults conducted in 2021 through the U-M Institute for Social Research, it adds to a growing pile of studies that have suggested a link between vision and dementia.
All of the older adults in the study were over the age of 71, with an average age of 77. They had their up-close and distance vision, and their ability to see letters that didn’t contrast strongly with their background, tested by a visiting team member using a digital tablet.
They also took tests of memory and thinking ability, and provided health information including any existing diagnosis of Alzheimer’s disease or another form of dementia.
Just over 12% of the whole group had dementia. But that percentage was higher – nearly 22% — among those who had impaired vision for seeing up close.
In addition, one-third (33%) of those with moderate or severe distance vision impairment, including those who were blind, had signs of dementia. So did 26% of those who had trouble seeing letters that didn’t contrast strongly against a background.
Even among those with a mild distance vision issue, 19% had dementia.
After the researchers adjusted for other differences in health status and personal characteristics, people with moderate to severe distance vision issues were 72% more likely than those with no vision issues to have dementia.
The gaps were smaller, but still large, for other types of vision impairment — except mild problems with distance vision, where there was no statistical difference.
Those who had more than one kind of vision impairment were also 35% more likely to have dementia than those with normal vision.
The new study builds on previous studies that had similar findings but relied on self-reported vision abilities rather than objective testing, or that were not representative of the U.S. population.
It also builds on previous work about cataract surgery that showed lower rates of dementia over time in adults who had had their distance vision restored by having surgery.
The authors, led by ophthalmologists Olivia Killeen, M.D., M.S. and Joshua Ehrlich, M.D., M.P.H., write, “Prioritizing vision health may be key to optimizing both sight and overall health and well-being. Randomized trials are warranted to determine whether optimizing vision is a viable strategy to slow cognitive decline and reduce dementia risk.”
But in the meantime, in an accompanying editorial, Sheila West, Ph.D., of the Wilmer Eye Institute at Johns Hopkins Medicine, wrote that the new study adds to accumulating evidence about the link between vision and cognitive issues.
“Equitable access to vision care services that prevent, reverse, or at least stave off progression of loss of sight is a worthy goal regardless of the potential impact on dementia and may be especially critical for those experiencing cognitive decline,” she wrote.
The study is based on data from the National Health and Aging Trends Study, which is based at the U-M Institute for Social Research and the Johns Hopkins University Bloomberg School of Public Health.
Last year, Ehrlich and colleagues published a paper in JAMA Neurology that used another ISR-based survey of older adults – the Health and Retirement Study – to estimate the percentage of Americans with dementia whose condition is likely related to their vision loss.
They calculated that 1.8 percent of all cases are vision-related, equating to more than 100,000 of the 6 million Americans with dementia. This study suggested that vision impairment should be considered alongside other more commonly recognized modifiable dementia risk factors.
That study was funded by the U-M Center to Accelerate Population Research in Alzheimer’s (CAPRA) through funding from the National Institute on Aging.
Killeen recently completed the National Clinician Scholars Program at the U-M Institute for Healthcare Policy and Innovation and is now at Johns Hopkins. Ehrlich is an assistant professor of Ophthalmology and Visual Sciences at Michigan Medicine and a research assistant professor at ISR, where he is a co-investigator of NHATS, as well as a member of IHPI.
In addition to Killeen and Ehrlich, the study’s authors also include Yunshu Zhou, M.S.
Funding: In addition to the National Institute on Aging grant that supports NHATS, and the U-M funding that supports the National Clinician Scholars Program, the study was funded by an unrestricted grant to the U-M Department of Ophthalmology and Visual Sciences by Research to Prevent Blindness.
About this vision and Alzheimer’s disease research news
Author: Kara Gavin
Source: University of Michigan
Contact: Kara Gavin – University of Michigan
Image: The image is credited to Neuroscience News
Original Research: Closed access.
“Objectively Measured Visual Impairment and Dementia Prevalence in Older Adults” by Olivia Killeen et al. JAMA Opthalmology
Abstract
Objectively Measured Visual Impairment and Dementia Prevalence in Older Adults
Importance
Estimates of the association between visual impairment (VI) and dementia in the US population are based on self-reported survey data or measures of visual function that are at least 15 years old. Older adults are at high risk of VI and dementia so there is a need for up-to-date national estimates based on objective assessments.
Objective
To estimate the association between VI and dementia in older US adults based on objective visual and cognitive function testing.
Design, Setting, and Participants
This secondary analysis of the 2021 National Health and Aging Trends Study (NHATS), a population-based, nationally representative panel study, included 3817 respondents 71 years and older. Data were analyzed from January to March 2023.
Intervention
In 2021, NHATS incorporated tablet-based tests of distance and near visual acuity and contrast sensitivity (CS) with habitual correction.
Main Outcomes and Measures
VI was defined as distance visual acuity more than 0.30 logMAR, near visual acuity more than 0.30 logMAR, and CS more than 1 SD below the sample mean. Dementia was defined as scoring 1.5 SDs or more below the mean in 1 or more cognitive domains, an AD8 Dementia Screening Interview Score indicating probable dementia, or diagnosed dementia. Poisson regression estimated dementia prevalence ratios adjusted for covariates.
Results
Of 2967 included participants, 1707 (weighted percentage, 55.3%) were female, and the median (IQR) age was 76.9 (77-86) years. The weighted prevalence of dementia was 12.3% (95% CI, 10.9-13.7) and increased with near VI (21.5%; 95% CI, 17.7-25.3), distance VI (mild: 19.1%; 95% CI, 13.0-25.2; moderate, severe, or blind: 32.9%; 95% CI, 24.1- 41.8), and CS impairment (25.9%; 95% CI, 20.5-31.3). Dementia prevalence was higher among participants with near VI and CS impairment than those without (near VI prevalence ratio: 1.40; 95% CI, 1.16-1.69; CS impairment prevalence ratio: 1.31; 95% CI, 1.04-1.66) and among participants with moderate to severe distance VI or blindness (prevalence ratio: 1.72; 95% CI, 1.26-2.35) after adjustment for covariates.
Conclusions and Relevance
In this survey study, all types of objectively measured VI were associated with a higher dementia prevalence. As most VI is preventable, prioritizing vision health may be important for optimizing cognitive function.
