Doctor reveals the tell-tale sign to detect dementia two decades before symptoms, and the secret lies in the eyes

Your eyes may be more than just the “windows to your soul” — they could also provide doctors with a 20-year head start in spotting dementia. A new study published in Alzheimer’s and Dementia by researchers at the Jackson Laboratory (JAX) in Maine suggests that routine eye exams might one day detect Alzheimer’s disease and other dementias long before memory loss sets in.

According to a report from Mirror, the research links subtle changes in the tiny blood vessels of the retina to a genetic mutation called MTHFR677C>T, which is present in up to 40% of people. These vascular changes — twisted vessels, narrowing arteries, and reduced branching — mirror abnormalities in the brain linked to poor blood flow and cognitive decline.

Why the retina matters
Lead researcher Dr. Alaina Reagan explained that the retina is essentially an extension of the brain. “Your retina is essentially your brain, but it’s much more accessible because your pupil is just a hole, and we can see tons of stuff,” she said in the report. That makes it a powerful biomarker for neurodegenerative diseases, allowing doctors to spot early trouble before symptoms surface.

The findings are especially significant because they suggest opticians could identify dementia risk during routine checkups, potentially two decades before families notice any memory problems.

Eye tests meet lifestyle choices
While genetics play a role, researchers emphasize that lifestyle can still shift outcomes. Earlier this year, a separate Nature study from Harvard Medical School revealed that following a Mediterranean diet reduced dementia risk by 35% even in people carrying two copies of the high-risk APOE4 gene. Diets rich in fruits, vegetables, legumes, olive oil, and fish may help repair brain tissue and improve energy metabolism, offsetting genetic disadvantages.

Neurologist Dr. Richard Isaacson, who was not involved in the eye study, told CNN that these findings highlight a broader truth: “Genes are not destiny. Imagine the power of combining diet with early detection tools like retinal scans.”

A new hope for prevention
The Jackson Laboratory team is now collaborating with clinicians at Northern Light Acadia Hospital in Maine to explore how these retinal findings translate to humans. If confirmed, eye exams could become a frontline tool in dementia prevention, offering millions of people an early warning system.

For patients and families, the message is twofold: your eyes could reveal risks decades in advance, and your daily choices — from diet to exercise — may still change the outcome.