Could a test to provide early warning for Alzheimer's be on the horizon? As this ScienCentral News video explains, researchers say just such a test is working in animals.
Alarm for Alzheimer's
Researchers at Boston's Brigham and Women's Hospital announced this week that a laser scan for the eyes has so far been 100 percent accurate as an early detector for Alzheimer's disease in mice.
"This is proof-of-concept evidence for early detection. It says that we're on the right track," lead researcher Lee Goldstein says. Goldstein's team used the laser scan eye test to compare mice that were genetically engineered to develop Alzheimer's with normal mice.
The laser scan found beta-amyloid protein in the eyes of the Alzheimer's mice well before any evidence was shown in the brain. In Alzheimer's patients the beta-amyloid protein ultimately builds up into plaques between nerve cells in the brain.
The laser directs a low-intensity beam of light into the lens of the eye, which bounces off of specific particles, similar to how the sun's light bounces off particles of water in clouds. This produces a "scatter pattern," which scientists use to look for beta-amyloid protein in the eye.
According to the National Institute on Aging, Alzheimer's disease affects up to 4.5 million Americans. Alzheimer's patients start to forget loved ones, dates, or how to do simple math. As the disease progresses, Alzheimer's patients can lose the ability to care for themselves and even to speak.
In 2003, Goldstein and others published in The Lancet that the beta-amyloid protein can be found in the eyes of Alzheimer's patients. "This was the first evidence outside of the brain that Alzheimer's was a systemic disorder," he says. "That's important because it allows us to monitor the progression of the disease in parts of the body other than the brain."
Goldstein has also developed another test, which uses eye drops to bind to the beta-amyloid protein. The eye drops contain a chemical which, when combined with the beta-amyloid protein, emits a specific molecular signal when exposed to a laser. Scientists read this molecular fingerprint to figure out precisely where the amyloid protein is located.
Goldstein says that these tests could mean better therapy options for those diagnosed early, potentially decades before lesions form in the brain. "Alzheimer's disease is very difficult to diagnose at any age," he says. "But in order for us to treat this disease we must be able to diagnose it early and intervene early."
Goldstein says the procedure is simple enough that it's similar to other types of eye tests. "The exam itself actually takes less than a second. We do multiple measurements so the whole course of the examination could take a minute or two," he says. "My thinking is that if this pans out for screening, you would want people to be tested by middle age ... part of your annual screening, like a glucose test."
Goldstein's eye test is now in the first stage of experimental trials in people.
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