PEOPLE who undergo surgery to treat cataracts may have a lower likelihood of developing Alzheimer’s disease, a new study suggests.

Of more than 3,000 older adults with the eye disease, those who had surgery were about 30 percent less likely to be diagnosed with Alzheimer’s in the coming years, researchers found.

The findings cannot prove cataract surgery helps protect against Alzheimer’s, said lead researcher Dr. Cecilia Lee. However, it provides strong evidence that it could be the case.

Lee and her colleagues were able to account for numerous other factors that might explain the finding. And even after doing so, cataract surgery was still linked to a reduction in Alzheimer’s risk.

“This evidence might be as good as we can get,” said Lee, chair of ophthalmology at the University of Washington School of Medicine.

A cataract is a clouding of the eye’s lens that can cause symptoms such as blurred vision, difficulty seeing at night, and seeing “halos” around lights.

Surgery to remove the cataract, and replace it with an artificial lens, can improve vision problems.

Past studies have linked cataracts, as well as other visual impairments, to an increased risk of dementia, including Alzheimer’s.

Lee’s team addressed those issues by using data on a large group of patients in the Kaiser Permanente health system. All had access to health care, and the researchers had detailed information on their health history.

They focused on 3,038 adults aged 65 and older who had cataracts and were free of dementia at the outset. Just under half underwent cataract surgery.

Over an average eight years, 853 patients were diagnosed with dementia, most often Alzheimer’s. But the risk was 29 percent lower among those who’d undergone cataract surgery, compared to those who hadn’t.

That reduction was seen after Lee and her team accounted for all the other variables they could — including whether people had physical disabilities or medical conditions like heart disease, stroke or diabetes. They also factored in body weight, exercise habits, education levels and smoking history — all of which have been tied to dementia risk.

Beyond that, researchers found no reduction in dementia risk among patients who underwent surgery for the eye condition glaucoma — a procedure that does not improve vision.

Lee said it’s plausible, in part, because vision problems limit older adults’ engagement with the world.

“If you can’t see well, you may not want to go out and socialize,” she said. “Or you may not want to exercise because you’re worried about safety.”

Like physical exercise, social and mental stimulation are thought to support healthy brain aging.

Another theory, Lee said, relates to blue light. Over time, cataracts can yellow, and that specifically blocks blue light. Certain specialized cells in the eye’s retina are very sensitive to blue light, Lee noted, and they have been linked to both sleep cycles and cognition (memory and thinking skills).(SD-Agencies)