Aug. 4, 2010 -- The race is on to finalize proposed new ways to help diagnose Alzheimer's disease early, even before any symptoms occur. The newly proposed diagnostic criteria were developed by experts from the National Institute on Aging and the Alzheimer's Association and cover three stages of the disease: pre-clinical Alzheimer's, mild cognitive impairment, and Alzheimer's dementia.
Promising new drugs to treat Alzheimer's are in the pipeline, which is why the researchers who are developing the new diagnostic criteria must hit the ground running, experts said during a media briefing sponsored by the Alzheimer's Association. About 5.3 million Americans have Alzheimer's disease, most of them aged 65 and older, according to statistics from the Alzheimer's Association.
"We want to be ready because labs are churning out all these new possible products and clinical trials are under way, and if the results should be positive, the idea is that they will work better in someone whose brain is relatively intact so the earlier we can diagnose someone as being on track for Alzheimer's disease, the better these agents may work," says Creighton Phelps, PhD, director of the Alzheimer's Disease Centers Program in the division of neuroscience at the National Institute on Aging in Bethesda, Md.
"If we had a drug that stops or delays the onset of Alzheimer’s disease, the demand for this diagnostic criteria would be immediate," says Steven DeKosky, MD, vice president and dean of the University of Virginia School of Medicine in Charlottesville. "When the drugs are ready, we will be ready to identify Alzheimer's disease in all three stages."
Likening Alzheimer's disease diagnosis to that of heart disease, he says "we want to identify people who are at-risk and have no symptoms and when appropriate, treat them so they never have these symptoms emerge or we can significantly delay their onset."
People with known heart disease risk factors such as high cholesterol and high blood pressure are identified and treated early on the basis of these risk factors so that they do not go on to have a heart attack or stroke. "This is exactly where we are going in Alzheimer's disease," DeKosky says.
Early Alzheimer's Screening Tests on the Horizon
In the past, Alzheimer's disease was only accurately diagnosed after death, when doctors performed an autopsy to examine changes in brain tissue.
But that was then. Now, there are new imaging biomarkers being developed that can help doctors identify risk of Alzheimer's disease earlier.
Changes in the brain triggered by Alzheimer's disease develop slowly over many years, which is why it's important to catch the disease earlier, says Guy McKhann, MD, professor at the Mind/Brain Institute at Johns Hopkins University in Baltimore.
"The disease itself starts many years before the dementia appears," he says. That said, "these tests are not ready for prime time except under very controlled circumstances."
Marilyn Albert, PhD, a professor of neurology at Johns Hopkins University in Baltimore, agrees. "We don’t think they are ready to be used by clinicians in the community yet," she says. "These biomarkers and their cut-offs need to be standardized across the board before they can be used outside of research settings."
Biomarker Tests Not Ready for Prime Time, Yet
"We need to standardize biomarkers and diagnostic criteria so ... it means the same thing across all centers," says Reisa A. Sperling, MD, an associate professor of neurology at Brigham and Women's Hospital in Boston.
Phelps adds that using these tests before they are validated could do more harm than good.
"In some studies conducted by the best labs in the world, there was a 30% discrepancy among results, and until they validate a better way to do some of the measurements, there may be too many false-positives and we would be telling people they were in trouble when they weren't," he says.
That's not to say you must sit idly by while researchers scurry to complete their task, Sperling says.
"Do everything possible to keep socially, physically and mentally active and lead a healthy lifestyle," she says.
"If you are seeing any kind of symptoms in yourself or your family like getting confused or forgetting things or short-term memory loss that is happening more regularly and getting worse, seek out advice form a specialist or memory disorders clinic," Phelps says. These subtle cognitive changes may appear a decade before the onset of dementia.
Volunteering to participate in clinical trials evaluating Alzheimer's risk factors and new drugs is another way to help move this field forward, McKhann says.
"If you have family history of Alzheimer's disease or other concerns about your risk, keep an eye on trials and be open to volunteering," he says.
The Alzheimer's Association and the National Institute on Aging launched www.alz.org/research/diagnostic_criteria/overview.asp to solicit input from additional experts. The criteria are open for comment until September 2010, and then the approved criteria will be published in a peer-reviewed medical journal.