Even when wearing glasses or contacts, those who scored worse on vision tests were also more likely to have concerning scores on cognitive tests.
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 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 United States population.