Eye Exam May Reveal Early Alzheimer's Plaque

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Someday clinicians may gaze into the eyes of patients to determine if they have evidence of a classic sign of Alzheimer’s disease: plaque. Scientists have found the plaque that accumulates in the brain of people with Alzheimer’s disease also builds up in the retina, and it can be seen earlier than in the brain.

Although there is no cure for Alzheimer’s disease, researchers are always looking for ways to detect it early so individuals can take immediate steps to slow progression of the disease. A variety of early diagnostic efforts are underway, including the identification of certain biomarkers in the cerebrospinal fluid, and an x-ray technique that can “see” the amyloid plaques in the brain, which current imaging techniques are unable to do.

In fact, because there are no noninvasive brain-imaging techniques that can adequately identify amyloid plaques, the only way to definitively diagnose Alzheimer’s disease is at autopsy.

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This newest approach was initiated after scientists at Cedars-Sinai Medical Center, along with colleagues from the Weizmann Institute of Science in Israel and the University of Southern California, found amyloid plaques in the retinas from deceased Alzheimer’s patients. They then used a noninvasive eye exam to examine the retinas of live mice that had been genetically modified to have Alzheimer’s disease.

The researchers found they could detect plaques in the retinas of the genetically modified mice before the plaque appeared in the brain. The high-resolution optical imaging technique they developed to monitor the plaque in the mice is an adaptation of an existing system used to examine the eyes of rodents.

Curcumin, a natural component of the spice turmeric, was used to label and detect plaque in the retinas. The curcumin attaches itself to amyloid plaques and makes them visible when viewed microscopically. The scientists chose the retina as a target for noninvasive imaging because it is easy to observe, and, unlike other parts of the eye, it is part of the central nervous system and has direct connection with the brain.

The authors believe these and other observations made during their studies establish the potential of an eye imaging technique as a tool for diagnosis of early Alzheimer’s disease via plaque on the retina.

SOURCE:
Cedars-Sinai Medical Center news release, June 24, 2010

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