Eyesight loss could be linked to dementia. If confirmed, it could be officially recognized as a risk factor for the disease, according to a new pivotal study.

Widely accepted risk factors for dementia include hearing loss, smoking, diabetes and high blood pressure. These can influence about 40% of people with dementia. Eyesight loss is not listed as a factor. 

A research team at University of Michigan evaluated data from about 3,000 adults who were 71 and over as part of the National Health and Aging Trends Study. They tested how well the people could see, and recorded scores on short- and long-distance vision, as well as how well they could see objects put up against different backgrounds. They cross-checked the data to see who had dementia, which is how they picked up on the correlation. People who had eyesight loss were more likely to have dementia compared to those with no vision problems. 

“This is a crucial time for dementia research, as evidence builds about how factors such as sight loss are linked to dementia,” Susan Mitchell, PhD, head of policy at Alzheimer’s Research UK, said in a statement. “Studies like this are crucial for identifying possible new dementia risk factors and ultimately working out how to potentially prevent some cases of dementia from happening in the first place.”

She added that the study gives new evidence that ties in with past research. 

“But this isn’t definitive, and it will be important for future studies to find out precisely what is causing this apparent link, as this will determine what, if any, potential there is for prevention,” Mitchell said. 

“There are several possibilities — for example, diabetes is a key risk factor for dementia, and this condition can also cause vision problems. Or it might be that there are shared pathways in the brain that cause both vision loss and a decline in memory and thinking abilities,” Mitchell added.

If researchers do confirm the link, it could mean that people can take steps to minimize sight problems as they age, which could lower their risk for dementia, Mithcell said. The results were published in the Journal of the American Medical Association (JAMA) Ophthalmology.