TAMPA — Told of a new test that could determine whether they would likely develop Alzheimer's disease, a college classroom full of retired professionals was instantly abuzz.
''Where can I sign up?'' said Jim Weiss, 78.
Like a number of his classmates at his USF lifelong learning class last week, Weiss was willing to set aside a frightening prospect in favor of personal control.
"I'd want to know, so I can do something about it if possible," such as participate in a clinical trial, said the retired computer professional. But his wife, Patricia, 77, probably wouldn't be so keen, he said.
The couple illustrate a dilemma that until now was only theoretical, because there has been no reliable test to predict the memory-robbing disease. Now the recent federal approval of a radioactive dye that can detect beta amyloid, a protein found in the brains of people with Alzheimer's, will make early detection more of a possibility.
The presence of the protein doesn't mean the disease will definitely develop, but it does increase the chances. The hope is that if found early, the disease that afflicts more than 5 million Americans could be stopped.
But at the same time, experts — including the national Alzheimer's Association — worry about how such a test might be used. Though researchers and doctors expect the dye will mostly be used in clinical trials, they'll also need to figure out how to deal with people who simply want to know if they're at increased risk of the disease.
Dr. David Morgan, head of the University of South Florida's Byrd Alzheimer's Institute, was the guest speaker at Weiss' class. He said the center might offer the scan when the dye becomes available in a few months.
But Morgan recognizes there are great risks in telling someone they're likely to develop Alzheimer's, when there is no cure.
"This must be approached very deliberately, with highest concern for the emotional impact on the individual," he said.
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The Food and Drug Administration approved the radioactive dye, called florbetapir (name brand Amyvid), for use in adults being evaluated for Alzheimer's disease or other causes of dementia. The test can confirm or rule out Alzheimer's as a cause of cognitive decline.
The dye allows researchers to see what was once apparent only in an autopsy. It is injected into the patient and binds to beta amyloid in the brain, which is visible through a positron emission tomography, or PET, scan. It's widely believed that amyloid buildup triggers a series of events that kill brain cells, leading to memory loss.
Research, however, has shown that amyloid begins to build up many years before Alzheimer's symptoms appear. Morgan said the dye could be used "off-label" as a way to identify people before symptoms appear to see if any treatments might slow or stop its progression.
Approved drugs, such as the popular Aricept, treat the symptoms of Alzheimer's. But more than 80 others are being tested, including some aimed at reducing amyloid buildup.
"I really believe that this is the first major step on a pathway to a cure," Morgan said.
But a positive amyloid scan only means you're more likely to get Alzheimer's, not that you definitely will get it.
In a statement, the national Alzheimer's Association called the FDA's approval of the Amyvid "a double-edged sword." It will expand clinical and research opportunities. But "the fact that all of the potential uses of this product are not crystal clear tempers our enthusiasm."
The group also expressed concern about "less than scrupulous operators offering imaging services and making unrealistic promises" about its value.
Morgan said that later this month in New Orleans, during the annual meeting of the American Academy of Neurology, the dye and its proper uses will be a major topic of discussion.
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Morgan said the dye likely won't be available until late June or early July. Medicare and private insurance won't pay for testing a person who has no symptoms but wants to know if they have amyloid buildup, since that's an off-label use, he explained.
What would the scan cost? Hard to know, since the dye's manufacturer, Avid Radiopharmaceuticals, Inc., hasn't yet set its price.
A key consideration is how results would be shared with the patient.
Celisa Bonner, who organizes Alzheimer's support groups at Madonna Ptak Center for Alzheimer's and Memory Loss at Morton Plant Mease in Clearwater, said counseling would need to be offered.
She said the center offers a test to see if someone has a genetic marker for Alzheimer's, a less reliable indicator of future disease than the new amyloid scan.
If they test positive? "We just try to educate people," she said, noting that changes in diet, exercise and stress level might help.
Weiss said several people in his lifelong learner's class expressed interest in having the test. But younger people might sign up too.
Matt Humphreville, 46, of Largo has a father with Alzheimer's disease, and he knows that puts him at slightly greater risk.
"I'd want to find out," he said. "I don't want to take the ostrich approach and just hope I don't get it.
"We may not have a drug to cure this yet, but maybe I can start making lifestyle changes, such as diet and exercise, with the hope of delaying anything."
Richard Martin can be reached at firstname.lastname@example.org or (813) 226-3322