15 Apr 2023
Signs of Alzheimer's disease in the eyes - Signs of Alzheimer's disease in the eyes - Study. Signs of Alzheimer's disease first appear in the eyes The eyes are a reflection of a person's cognitive health. Photo: Profimedia The eyes are more than a window to the soul. They are also a reflection of a person's cognitive health. This is where the first signs of Alzheimer's disease can be detected, according to a study cited by CNN.

“The eye is the window to the brain,” said ophthalmologist Dr. Christine Greer, director of medical education at the Institute for Neurodegenerative Diseases in Boca Raton, Florida.
“You can see right into the nervous system by looking at the back of the eye at the optic nerve and retina,” she explains. Research has explored how the eye can help diagnose Alzheimer’s disease before symptoms appear. The disease is well advanced by the time memory and behavior are affected.

“Alzheimer’s disease starts in the brain decades before the first symptoms of memory loss,” said neurologist Richard Isaacson. If doctors can identify the disease in its early stages, people may be able to make healthy lifestyle choices and control their “modifiable risk factors, such as high blood pressure, high cholesterol and diabetes,” Isaacson said. To see how early signs of cognitive decline appear, the Alzheimerstudy authors examined tissue donated from the retinas and brains of 86 people with varying degrees of mental decline. “Our study is the first to provide in-depth analyzes of the protein profiles and molecular, cellular and structural effects of Alzheimer’s disease in the human retina and how these correspond to changes in brain and cognitive function,” said study lead author Maya Koronyo -Hamaoui, professor of neurosurgery and biomedical sciences at Cedars-Sinai in Los Angeles. “These retinal changes correlated with changes in parts of the brain called the entorhinal and temporal cortices, a center for memory, navigation and time perception,” Koronyo-Hamaoui said.
The researchers collected retinal and brain tissue samples over 14 years from 86 human donors with Alzheimer’s disease and mild cognitive impairment — the largest pool of retinal samples ever studied, according to the authors. The researchers then compared samples from donors with normal cognitive function to those with mild cognitive impairment and those with advanced Alzheimer’s disease. The study, published in February in the journal Acta Neuropathologica, found significant increases in beta-amyloid, a key marker of Alzheimer’s disease, in both people with Alzheimer’s and early cognitive decline. Microglial cells decreased by 80% in those with cognitive problems, study shows. These cells are responsible for repairing and maintaining other cells, including clearing beta-amyloid from the brain and retina. “Markers of inflammation were also found, which may be an equally important marker for disease progression,” said Isaacson, who was not involved in the study. “The findings were also evident in people with no or minimal cognitive symptoms, suggesting that these new eye tests could help with early diagnosis,” he added.