The eyes are more than a window to the soul—they're also a reflection of a person's cognitive(认知的) health. Research has been exploring how the eyes may help in diagnosing(诊断) Alzheimer's disease before symptoms(症状) begin.
"Alzheimer's disease begins in the brain decades before the first symptoms of memory loss," said Dr. Richard Isaacson, an Alzheimer's preventive neurologist at the Institute for Neurodegenerative Diseases. If doctors are able to identify the disease in its earliest stages, people could then make healthy lifestyle choices and control their "risk factors, like high blood pressure, high cholesterol and diabetes," Isaacson said.
Then how early can we see signs of cognitive decline? To find it out, a recent study examined donated tissue from the retina(视网膜) and brains of 86 people with different degrees of mental decline. "Our study is the first to provide in-depth analyses 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 and biomedical sciences at Cedars-Sinai in Los Angeles.
Researchers in the study collected retinal and brain tissue samples over 14 years from 86 human donors with Alzheimer's disease and mild cognitive damage—the largest group of retinal samples ever studied, according to the authors. Researchers then compared samples from donors with normal cognitive function to those with mild cognitive damage and those with later-stage Alzheimer's disease.
The study, published in February in the journal ActaNeuropathologica, found significant increases in beta-amyloid, a key marker of Alzheimer's disease, in people with both Alzheimer's and early cognitive decline.
"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 eyes."