Not every early sign of Alzheimer’s disease is related to memory loss or other changes in cognitive function. Sometimes, it’s your eyes that show early warning signs of dementia or Alzheimer’s.

Here’s what you need to know about your eyes and Alzheimer’s disease.

Retinal Changes and Alzheimer’s

Certain changes in the retina (the area at the back of the eye that detects light) may be early signs of Alzheimer’s disease. In a study from 2023, researchers looked at brain and retinal tissue from 86 different people. The samples came from people with normal cognitive function, mild cognitive impairment, and later stages of Alzheimer’s disease.

They found significant differences between the three groups. People with any sort of cognitive impairment had more beta-amyloid proteins in their retinas than those with normal cognitive functioning. These are the same proteins that build up in the brains of people with Alzheimer’s and form plaques.

Researchers also found other differences in people with Alzheimer’s. There was 80 percent less activity in the cells that are supposed to clear beta-amyloid proteins from both the retina and the brain. There was also more activity in the systems that cause inflammation and in the immune system around the beta-amyloid plaques. While researchers don’t yet know what all of this means, these findings help improve our understanding of the disease.

This study supports and adds details to earlier research. In 2018, researchers found that a particular area of the retina often becomes enlarged in people who later develop Alzheimer’s. A study in mice showed that retinas affected by Alzheimer’s reflect light differently in scans compared to unaffected retinas.

Why the Retina?

These last two studies highlight changes in the retina, while the first study starts to explain why doctors and researchers might notice those changes. While we don’t have the whole story yet, we do have some understanding of what might be happening in the brain.

Both the retina and the optic nerve (the part of the eye that sends information from the retina to the brain) are actually extensions of brain tissue. This connection may help explain how the brain gathers and organizes the visual information received by the eyes. While we don’t yet know exactly how it all works, it makes sense that conditions that affect the brain might also affect the eyes. Researchers are now sure that there is a connection between brain and eye tissue, and they plan to continue studying it further.

Posterior Cortical Atrophy and Alzheimer’s

Posterior cortical atrophy (PCA) is a rare condition that affects the brain and usually starts at a younger age. It involves the death of brain cells in specific areas of the brain cortex (the occipital and parietal lobes) over time. Eventually, this can lead to different kinds of vision problems and difficulties with spatial judgment.

Research shows that posterior cortical atrophy is linked to underlying Alzheimer’s disease. However, it’s unclear how many people who live with PCA also have Alzheimer’s. According to a 2024 study, PCA symptoms occur in up to 10 percent of people with Alzheimer’s. Additionally, 94 percent of people with PCA had Alzheimer’s pathology, meaning they showed the same brain changes, like plaques and tangles, that are typical of Alzheimer’s disease. The remaining 6 percent had other types of dementia.

Other causes of posterior cortical atrophy include other types of dementia or brain damage, like Lewy body disease, frontotemporal lobar degeneration, or corticobasal degeneration.

Using Eye Scans To Diagnose Alzheimer’s

These findings could lead to better ways to diagnose Alzheimer’s, including earlier diagnoses.

Currently, Alzheimer’s is diagnosed only after doctors rule out other possible causes of the symptoms. This usually involves many different assessments. Doctors might test a person’s thinking and memory. They may also speak with a person’s family and friends, perform physical exams, and use brain imaging scans.

There are other ways to diagnose Alzheimer’s, but they can be expensive and complicated. Some methods are even risky for the person being diagnosed. These include a positron emission tomography (PET) scan or testing a person’s cerebrospinal fluid, which requires getting a spinal tap to collect the fluid.

Because of these downsides, most people rely on assessment methods. However, this process can be lengthy and requires significant symptoms to be present.

Right now, there’s not enough information to perform eye scans for diagnosing Alzheimer’s. However, there are a number of other possibilities. Some types of retina scans can detect changes without having to dissect retinal tissue. These scans have successfully identified the condition in mice, so there’s hope they could do the same in people.

There is another test that also looks promising. Called fluorescence lifetime imaging ophthalmoscopy (FLIO), it examines how certain particles in the retina behave. One study from 2019 found that certain results from this test are linked to the buildup of beta-amyloid proteins. If these results are confirmed in other studies, this could provide an easier way to diagnose Alzheimer’s early.

It will also be important for doctors to know how to test for posterior cortical atrophy and what positive results might mean. If ophthalmologists can detect it early, people may be eligible for Alzheimer’s treatments that work best when the condition is in its early stages. If they’re not diagnosed until later, people might miss the chance to get the most benefit from these treatments.

Talk to Your Doctor

Right now, the best thing you can do for yourself or a loved one is make sure they receive good, ongoing eye care. Anyone experiencing vision changes should talk to their eye doctor right away. There might be another cause for these changes, or they may need additional testing.

Similarly, if you notice symptoms like memory loss or confusion in yourself or a loved one, it’s important to see a health care provider as soon as possible. This can be a family doctor or a neurologist. They can help figure out what is causing the symptoms, whether it's Alzheimer’s disease or something else.

Talk With Others Who Understand

At myALZteam, you’ll find the social network for people with Alzheimer’s and their loved ones. On myALZteam, more than 86,000 members come together to ask questions, give advice, and share their stories with others who understand life with Alzheimer’s.

Have you noticed any links between Alzheimer’s and eye-related diagnoses? Share your experience in the comments below, or start a conversation by posting on your Activities page.