Peripheral Retina May Help Detect Early Signs Of Alzheimer's Disease Before Brain Damage: Study

The outer area of the retina, or the peripheral retina, could offer a window into an early detection of Alzheimer's disease long before irreversible brain damage occurs, and a routine eye exam may thus potentially help with an early diagnosis of the neurodegenerative condition, according to a new study. "The eyes are indeed a window into the brain, but our study reveals that we have been looking at the wrong part of the window. While most clinical eye exams focus on the central retina, the most critical early indicators of Alzheimer's disease (AD) appear to be hidden at the periphery of the eye," author Stephen Wong, from Houston Methodist Hospital in the US, said.

"By identifying these retinal changes that occur before the brain's 'plumbing' system fails, doctors may eventually be able to use routine eye exams to catch and treat the disease years before memory loss begins," he said.

Previous research has found that an accumulation of amyloid protein -- a waxy complex protein resembling starch resulting from degeneration of a tissue -- in the retina correlates with amyloid protein deposition in the brain (a hallmark of AD), suggesting that the retina may reflect central disease processes, the researchers said.

The study, published in the Journal of Alzheimer's Disease, was conducted in mouse models and revealed how 'Muller glia', or retinal support cells, respond to the earliest stages of the disease and undergo significant cellular and structural changes before other symptoms of the neurodegenerative condition appear.

"Since the peripheral retina contains more glial cells than the central retina, we wanted to understand how these types of cells and blood vessels interact in different parts of the retina in early-stage AD," first author Glori Das, a graduate research assistant at the Wong Laboratory at Houston Methodist, said.

The researchers found that 'Aquaporin-4', a protein in the central nervous system that helps flush out metabolic waste, including Alzheimer 's-linked proteins, increases in the earliest stages of the disease. This shows up as stress in the peripheral retina, evidenced by the increased size and number of glial cells, they said.

Wong said the study result is visual evidence that the body is working harder to maintain balance before the system eventually fails in later stages of the disease.

He said the study could change how AD is diagnosed and monitored and could provide a new target for early-intervention drug development.

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