First Signs of Alzheimer's May Appear in the Eyes

The eyes may be the window to the soul, but they also reveal what’s happening in our brains. A newly published study examined retinal and brain tissue from 86 post-mortem samples of people who had been diagnosed with Alzheimer’s disease or mild cognitive impairment. The investigators found that changes in the retina correlated with changes in the brain. This discovery means that doctors may be able to diagnose Alzheimer's disease and early cognitive decline by a simple and noninvasive eye exam.

“Our study is the first to provide in-depth analysis of the protein profiles and the molecular, cellular, and structural effects of Alzheimer's disease in the human retina and how they correspond with changes in the brain and cognitive function,” said senior author Maya Koronyo-Hamaoui, a professor of neurosurgery at Cedars-Sinai in Los Angeles, according to CNN.

If doctors can identify the disease in its earliest stages, people could make healthy lifestyle choices and “control their modifiable risk factors, like high blood pressure, high cholesterol and diabetes,” said Dr. Richard Isaacson, a world-renowned neurologist and an expert on Alzheimer’s prevention. “Alzheimer’s disease begins in the brain decades before the first symptoms of memory loss.”

The study found significant increases in beta-amyloid plaque, a key marker of Alzheimer’s disease, in people with both Alzheimer’s and cognitive decline. It also discovered that microglial cells responsible for repairing and maintaining other cells, as well as clearing out amyloid plaque, declined by 80% in people with cognitive issues.

According to Ophthalmology Times, the investigators said, “Our findings provide  a novel and deeper understanding of the susceptibility of the retina to Alzheimer’s disease processes, including molecular, cellular, and structural abnormalities that can be detected in the earliest stages of functional impairment.”

Isaacson pointed out that the researchers also found markers of inflammation and tissue atrophy, which is another sign of disease progression. “The findings were also apparent in people with no or minimal cognitive symptoms, which suggests these new eye tests may be well-positioned to aid in early diagnoses,” he said, according to CNN.

“These findings may eventually lead to the development of imaging techniques that allow us to diagnose Alzheimer's disease earlier and more accurately,” Isaacson said, “and monitor its progression by looking through the eye.”