COPENHAGEN – When it comes to beta-amyloid plaques, the eyes may be more than a poetic window to the soul – they also may be mirrors of pathology developing in the brain.
It turns out that the eye, as a virtual extension of the brain itself, accumulates the same amyloid pathology that damages the brain when Alzheimer’s disease strikes. Visualizing these plaques in the retina and in the lens may eventually become a low-cost, noninvasive screening tool for early disease, according to research presented at the Alzheimer’s Association International Conference 2014.
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"Our first 45 subjects showed a strong correlation between retinal amyloid and brain plaques," said Shaun Frost of the Commonwealth Scientific and Industrial Research Organisation (CSIRO) in Australia. "In fact, we had 100% sensitivity and no false positives, something that’s critical for an Alzheimer’s test, because we don’t want to leave anyone behind when it comes to early signs."
Curcumin, an extract of the spice turmeric, is the fluorescent agent in the test. Mr. Frost said investigators were first drawn to it because some studies suggest a lower rate of Alzheimer’s in India, where turmeric is a common seasoning.
Paul Hartung, president of Cognoptix in Acton, Mass., said his company focuses on lens amyloid, which shows a correlation to brain plaques. Cognoptix is accumulating data on a device that identifies plaques using dynamic light scattering and a fluorescent molecule delivered in an ophthalmic ointment.
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In the phase II study he presented, the test differentiated 20 people with Alzheimer’s from 20 healthy controls with an 85% sensitivity and 95% specificity. It also correlated significantly with brain plaques seen on PET amyloid imaging.
A phase III trial is in the works, after which Cognoptix intends to seek approval from the Food and Drug Administration. Mr. Hartung hopes the device could be marketed by 2016.
The lens amyloid trial is a collaboration between CSIRO; Edith Cowan University in Mt. Lawley, Australia; the McCusker Alzheimer’s Research Foundation; California-based NeuroVision Imaging; and the Australian Imaging, Biomarker & Lifestyle Flagship Study of Ageing. Mr. Frost had no financial disclosures. Mr. Hartung is a full-time employee of Cognotpix, which is developing the test for commercial use.
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