This Routine Scan Could One Day Detect Alzheimer’s Before Cognitive Symptoms Pop Up

Alzheimer's patient working on puzzle

Vision changes are something you probably expect as you get older. You may need a stronger contact lens prescription, struggle to drive in the dark or carry reading glasses everywhere you go. Research suggests that some these vision shifts could signal brain changes that might be early signs of Alzheimer’s disease.

A 2023 study published in the journal Acta Neuropathologica examined tissue from the brain and retina of 86 individuals and compared samples from donors with normal cognitive function to samples from people with mild cognitive impairment in the early stages of Alzheimer’s and people with late-stage Alzheimer’s. Researchers found increases in the protein beta-amyloid, which is a marker for Alzheimer’s, in individuals with Alzheimer’s and cognitive decline.

The study also found that people with cognitive issues saw an 80% decline in microglial cells, which help clear beta-amyloid from the brain and retina. Inflammation and atrophied tissue were also discovered in cells of the retina of people with cognitive decline.

Many of the changes in the retina are associated with changes to parts of the brain that are connected to memory, navigation and perception of time, according to researchers. They said the findings could possibly lead to the development of imaging tests in the future that may be able to diagnose Alzheimer’s earlier and monitor its progression by examining the eye.

The study follows other research suggesting that an optical coherence tomography angiography (OCTA) scan could potentially help doctors detect signs of Alzheimer’s disease in the small veins located in the back of the eye.

While eye scans can’t yet diagnose Alzheimer’s disease, Dr. Simon Law, MD, an ophthalmologist at UCLA Health, says these studies are helping doctors better understand the connection between the eye and Alzheimer’s disease. “It’s an exciting development,” he adds.

What Is an OCTA Scan?

OCTA scans use light waves to obtain detailed images of the retina and its blood vessels, explains Dr. Raj Maturi, MD, clinical spokesperson for the American Academy of Ophthalmology. The scan is used for early detection of eye conditions, including age-related macular degeneration, diabetic retinopathy, macular edema and glaucoma.

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“Your ophthalmologist may recommend an OCTA scan if they suspect any issues in the back of the eye,” he says. But it can’t yet detect the signs of cognitive decline.

Still, the research “adds to the growing body of studies aiming to understand the potential connection between the retina and dementia,” Dr. Maturi says. But, more studies are needed to fully understand the link between retinal changes and Alzheimer’s disease.

“It's a very big question that they have to research in the future,” Dr. Law says. “It's still an exciting area. And, OCTA imaging is getting better and better, but there's still a long way to go.”

What’s the Link Between Alzheimer’s and Eye Health?

Evidence suggests that diseases of the brain also affect the eyes, as the optic nerve and retina are brain tissue that extends beyond the braincase, according to the American Academy of Ophthalmology. While Alzheimer’s and dementia damage brain cells, the conditions also affect the retina. But, there aren’t yet eye tests that can diagnose dementia.

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“There are still a lot of unknowns when it comes to the connection between eye and brain health, but the theory is that because the retina is made up of brain tissue and the retina is connected to the brain through the optic nerve, changes in the brain from a disease like Alzheimer’s may show up in the eye as well,” Dr. Maturi says. “Retinal cells are, after all, just specialized brain cells.”

Research also suggests that people who have glaucoma are at a higher risk for Alzheimer’s disease, Dr. Law says.

“It’s a degenerative process,” he adds. “Our body is constantly in a regenerative and degenerative process. When we get older, we degenerate more than we regenerate.”

While there’s a likely connection between Alzheimer’s disease and eye problems, there are no specific eye symptoms that suggest cognitive decline, Dr. Maturi says. Still, having an ophthalmologist examine your eyes can tell you how your body is doing.

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“Your eyes reflect the overall health of your blood vessels, nerves and tissues,” he explains. “That’s how ophthalmologists sometimes detect systemic diseases like diabetes, heart disease and sexually transmitted diseases.”

If you notice any of the early signs of Alzheimer’s disease, it’s important to see your doctor, Dr. Law says. These include memory loss, difficulty completing familiar tasks, confusion with place or time, misplacing things, withdrawal from social circles and changes in mood, according to the Alzheimer’s Association.

How to Protect Your Eyes As You Age

The American Academy of Ophthalmology recommends all healthy adults get an eye exam by age 40 and then every year or two after age 65, Dr. Maturi says.

“Some eye diseases can begin without any noticeable symptoms—that’s because your brain is good at filling in the blanks during the early stages of vision loss so you may not even notice any changes to your vision at all,” he explains.

Catching eye diseases early gives you the best chance of getting the treatment you need as soon as you can, Dr. Maturi says.

Other ways to protect your eyes as you age include wearing 100% ultraviolet ray-blocking sunglasses, which Dr. Maturi says you should wear every time you’re outside, even when it’s cloudy. Also, embrace a plant-forward diet with minimal ultra-processed foods, stop smoking and wear eye protection when working on projects around your home or playing sports.

Next, read about some important habits for memory retention.