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.
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."