Dementia is a general term for a group of disorders (including Alzheimer’s disease) that impair memory and thinking. There’s no cure for dementia and only a few approved treatments that work to slow progression of the condition, so prevention is key.

One way to help prevent dementia is to “avoid vision impairment,” according to the American Medical Association’s JAMA Neurology. Research suggests a link between certain types of vision issues and dementia.

A 2021 study in the British Journal of Ophthalmology reported that age-related macular degeneration (AMD), cataracts, and diabetes-related eye problems raised the risk of dementia by 26%, 11%, and 61%, respectively. Some studies have seen similar links between dementia and glaucoma.

“I’d never advise anyone to be worried,” says Evan Bayles, O.D. He’s an optometrist working in an America’s Best Contacts & Eyeglasses location in Newport, Kentucky. “Worrying doesn’t solve anything, and it could worsen any health condition. In fact, long-term stress can increase the risk of many eye diseases as well as dementia,” he says.

Being better informed, however, is a strategy Dr. Bayles fully supports. “While there’s likely a direct link between vision problems and dementia, to what degree is uncertain,” he says. “And there are action steps you can take to lower your risks, whatever they may be.”

Here, he offers a closer look at the connection between your brain and eyes and how to keep them both healthy.

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How might vision loss affect brain health?

One theory is that vision problems reduce brain activity in ways that can increase the risk of cognitive decline, says Dr. Bayles. (Similar connections have been found between hearing loss and reduced brain function.)

“When everything’s working well, your eyes send signals along nerve pathways to your brain, which lets you know what you’re seeing,” he explains. “That all happens in the blink of an eye. If those pathways start to see less action — say, because your vision is blurry or blocked by cataracts — the signal to the part of your brain related to vision weakens. If it stays weak for too long, even correcting the problem might not be enough to strengthen it back to full capacity.”

Another theory relates to something called cognitive overload. The brain isn’t great at multitasking. If it needs to work extra hard to help you see, it may not have the bandwidth for other tasks. This might lead to atrophy elsewhere in your gray matter.

Then there’s the lifestyle impact. Vision problems can prevent people from driving and getting together with loved ones. They can also hinder close-up tasks such as reading and doing brain-boosting puzzles. All these little daily moments go a long way to keeping your brain sharp.

Do other health problems increase your risk?

Health problems such as diabetes and heart disease affect your whole body, including your brain and your eyes.

For example, people with diabetes are at greater risk for a stroke, which can damage the brain, says Dr. Bayles. If blood sugar drops too low (as a result of overmedication), it can damage the brain’s memory center. And insulin resistance can lead to the formation of plaques and tangles in the brain, which are the hallmarks of Alzheimer’s disease.

Diabetes can also weaken tiny blood vessels in the eye that feed the retina, where cells absorb and convert light into electrochemical impulses that are then delivered from the eye’s lens to the optic nerve. This condition is called diabetic retinopathy.

Other vision conditions related to diabetes include macular edema. This is swelling in the part of the retina that handles sharp, straight-ahead vision. Cataracts and glaucoma are also more common in people with diabetes.

When you start to look at the big picture, it’s easy to see why it can all add up — and why it can be tough to tell exactly what’s at the root of the problem. Luckily, looking at the big picture is also a good way to lower your risk of health issues, including vision problems and dementia.

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What are some steps I can take to lower these risks?

What’s good for your eyes is generally good for your brain and body too, Dr. Bayles says. Here are a few smart places to start boosting your overall health.

Get all your yearly exams. “Preventive care is always useful,” Dr. Bayles says. “Not just yearly eye exams, but also yearly physicals that include a blood workup. In nearly everything, the earlier you catch a problem, the better the treatment and lifestyle adjustments can work.”

Follow your treatment plan. Whether you have a vision condition, a health condition, or a combination, you and your health care team can create a plan that works for you. If something is holding you back (cost, physical limits, willingness, or something else), let your doctors know ASAP so that they can try a different method.

Kick tobacco. Tobacco use raises your risk of cataracts, glaucoma, and AMD. Even secondhand smoke can harm your eyes. Fortunately, avoiding smoke can limit the damage and improve your eye health. Quitting can also help reduce your risk of heart disease, diabetes, stroke, and other health conditions, some of which have been linked to dementia.

Watch what you eat. Pick antioxidant-rich fruits and vegetables, especially dark green leafy ones and vitamin-C powerhouses such as citrus. They’re good for your eyes, brain, and body. Also keep alcohol intake moderate: More than one or two drinks a day (for women and men, respectively) can raise your risk of cataracts. As for other food groups, choose lean protein (instead of red or processed meats) and healthy fats (instead of saturated fats).

Take care of your mental health. Depression can impact your vision, Dr. Bayles says. If it causes a stress response, the pupils can be over-dilated. That can make you more sensitive to light and affect your ability to see details sharply.

“This may be what it means when people with depression say they ‘see the world in gray,’” he says. Having chronic medical or vision conditions can also impact your mental health. There’s a lot of interplay. Caring for your body can improve your emotions and mood as well.

Update your intake form accurately. When you do go for your eye exam, be honest about all your health conditions and symptoms.

“I’m paying attention to what your ‘yes’ answers are,” Dr. Bayles says. “Your eye doctor is not going to blame you or judge you. We just want to know what your starting point is so we can figure out how we can help.” 

Eager to read more? Check out 8 Easy Ways to Prevent Vision Problems for more can-do tips to add to your daily routine.