Alzheimer's Brain Scan Works, Says FDA: Would You Want to Know?
(CBS) Knowing Alzheimer's disease may be ravaging your brain five, 10, even 20 years before you start forgetting names, getting lost on familiar roads, or forgetting how to balance your checkbook... would you want doctors to look inside your brain, and see its tell-tale sign?
Every 70 seconds someone in America develops Alzheimer's disease, and if you're one of them, it's a good bet you'd want to know.
In what is being hailed as a research home run this week, scientists reported success with a high tech brain scan that lights up one of Alzheimer's calling cards, clumps of sticky proteins called amyloid plaque.
Right now, the only way to definitively diagnose Alzheimer's disease is at autopsy; if a patient died and had memory loss, and doctors see those characteristic amyloid plaques in their brain. But this new scanning technique allows doctors to see the proteins in a living person, with convincing accuracy.
The process is fairly simple: a patient is injected in the arm with the radioactive dye Florbetapir (its proposed brand name is Amyvid). The tracer travels to the brain and sticks to brain plaques, so they can be picked up on the PET scan.
In a study published in the Journal of the American Medical Association (link) , the scan accurately predicted the level of amyloid in the brain. Very low amyloid equals a very low likelihood of Alzheimer's; heavy amyloid signals a high likelihood a person will get the disease.
"Amyloid imaging techniques are already helping us in terms of the scientific understanding of Alzheimer's disease and the evaluation of some of our most promising treatments, " says Dr Eric Reiman, an author on the paper, and Executive Director of the Banner Alzheimer's Institute in Phoenix. "We're really excited about the role it could play in the clinical setting."
But there's a problem with just looking inside the brain and seeing amyloid - having amyloid does NOT equal, having Alzheimer's. Some 30 percent of people with amyloid never develop memory problems, and yet you must have an accumulation of amyloid plaques for a definitive Alzheimer's diagnosis. Its value may be in helping rule out the presence of Alzheimer's disease
It's humbling to meet Preston Keusch, who holds a doctorate in chemical engineering, and holds more than twenty patents. He was used to being able to do complex calculations in his head. But then the numbers began to confuse him and slow him down, and he began to lose names and facts. When his powers of thinking first started to slip about four years ago, he feared what most do: Alzheimer's. His is a common presentation - a patient who clearly is experiencing dementia, but for no clear reason. Keusch says he'd welcome a test that would allow doctors to see whether amyloid plaques are forming in his brain. "If it came out negative I'd be relieved, and if it were positive maybe they could start some kind of treatment that would slow it down, " says Keusch.
"It's more ammunition," says neurologist Dr. Gayatri Devi, clinical associate professor of neurology and psychiatry at New York School of Medicine.
While Alzheimer's is the most common form of dementia, many things can cause memory loss - depression, psychiatric disturbances, vascular problems, an underactive thyroid and of course, aging. A test that could rule out Alzheimer's would help doctors better manage patients' expectations about their illness, and of course allow them to tailor treatments to the real cause of the memory loss.
But the test is not quite ready for the doctor's office. An FDA Advisory Committee wants some key questions answered first. Are doctors who would employ the technique properly trained? Would they be able to interpret what they see? Experts also want to see a re-analysis of data, and proof it truly has clinical value before it can be approved. .
On the flip side, The FDA did say the test worked and no significant safety concerns were raised.
"We appreciate the careful and thoughtful review of our data today by the committee," said Dr. Daniel M. Skovronsky, CEO of Avid Radiopharmaceuticals, in a release to CBS News. "We are encouraged that they recommended a clear path toward approval."
Total costs for Alzheimer's add up up to a $172 billion dollars each year. While the amyloid PET scan would be expensive, and cumbersome, the hope is being better able to identify Alzheimer's pathology through brain scans may lead to simpler and easier methods, like blood and fluid tests, and perhaps, earlier and more effective treatments.
One thing is certain: the pharmaceutical companies that successfully tap into the "silver tsunami' market" - an American population that is aging, with more 10,000 more people turning 65 each day - will see a multi-billion dollar payoff.
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