It’s been said that the eyes are the window to the soul…but they may also be a window to the brain!

What’s new: Researchers have discovered that a noninvasive, experimental eye scan that examines the back of the eyes (the retinas) may detect signs of Alzheimer’s disease that usually appear long before any symptoms occur—and possibly pave the way for earlier treatment approaches that could change the course of the disease.

Background: Traditionally, the only way to officially diagnose Alzheimer’s disease was to analyze a person’s brain after he/she had died. Even though the use of positron emission tomography (PET) scans for living patients provides evidence of the disease and has recently become more widely used, this test is expensive, involves the use of potentially harmful radiation and requires the patient to be injected with radioactive tracers, which in rare cases cause an allergic reaction.

So what prompted scientists to investigate whether the eyes could provide important clues about Alzheimer’s disease?

When brain tissue from deceased Alzheimer’s patients is examined under a microscope, two types of protein abnormalities (known as plaques and tangles) appear that are characteristic of the disease. The plaques are made of clumps of a protein called beta-amyloid (believed to be an early sign of the Alzheimer’s disease process) that induce inflammation and cause damage to brain cells, while tangles form inside brain cells, where they prevent the transport of nutrients, causing the cells to die.

Based on earlier research suggesting that the eyes may provide important clues about brain health, scientists at Cedars-Sinai Medical Center in Los Angeles decided to further investigate this theory with a carefully designed study.

Study details: Ten patients with symptoms of mild-to-moderate Alzheimer’s disease and six younger, cognitively healthy individuals (controls) consumed a solution containing curcumin (a natural component of the spice turmeric) that caused the amyloid plaques in their retinas to “light up” during a high-definition eye scan. When the results were compared, there was a 2.6-fold increase in plaques in the retinas of the Alzheimer’s patients compared with the controls.

Implication: Analyzing the retina is a particularly appealing way to detect Alzheimer’s early on because an eye scan is relatively easy to repeat, which allows doctors to monitor patients and the progression of their disease to tell whether any treatments are helping. Note: The scan used in this study captures peripheral retinal regions that are not normally examined in a standard retinal exam.

Bottom line: While more study is needed to determine whether eye scans will ever become widely used to predict Alzheimer’s disease, stay tuned! If additional research confirms these findings in larger studies, eye scans could become a simple, inexpensive way to identify signs of Alzheimer’s years before symptoms appear.

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