New Guidelines Could Help Diagnose Alzheimer's Earlier
By Heather Maloney
Beth Israel Deaconess Medical Center Staff
For the first time in over 20 years, medical experts are proposing changes in the criteria for diagnosing
Alzheimer's disease, part of a new shift to try and identify and, eventually, treat the disease earlier.
The new guidelines, developed by the National Institute on Aging and the Alzheimer's Association, would mean that new technology like brain scans could eventually be used to detect the disease even before symptoms develop.
According to the Alzheimer's Association, there are over 5 million Americans living with this disease today. Most are diagnosed very late, when they begin to exhibit obvious signs of dementia. The goal of the new criteria is to identify people with biomarkers early, before they actually lose their memories.
Currently, Alzheimer's disease is typically diagnosed when a patient exhibits signs of steadily progressing dementia , like memory loss and an inability to carry out day-to-day activities. This is often coupled with a pathologist's report of plaque and another abnormality, known as tangles, in the brain after death.
The new guidelines include criteria for three stages of the disease: preclinical disease, mild cognitive impairment due to
Alzheimer's disease and
Alzheimer's dementia. While the new guidelines should make diagnosing the final stage of the disease more definitive, there is still some debate over a less-certain early diagnosis.
Dr. Daniel Press, a neurologist at Beth Israel Deaconess Medical Center and assistant professor of neurology at Harvard Medical School, discusses the new guidelines:
Q. How significant are these new guidelines?
Dr. Press: The criteria for diagnosing Alzheimer's has remained almost unchanged since the 1980s. Previously, a diagnosis of probable Alzheimer's disease was based solely on clinical presentation, with other potential causes of dementia (such as cerebrovascular or
Parkinson's disease) ruled out.
We now think that there's a long period of time before someone develops full-blown Alzheimer's, when the disease is just beginning. The hope is that the treatments now being developed will work best in these very early stages. So there's lots of research going into how early someone can be diagnosed.
Q. What are some of the challenges these new guidelines present?
Dr. Press: The challenge comes when seemingly healthy people begin to have some issues, and we need to decide if it's worth generating a great deal of concern for that person by giving them all kinds of tests. I think that right now it is still a little too early to screen people who have totally normal memory. But for people with some impairment, there are things we can do now to slow down the progression of memory troubles.
While I think these new guidelines are important, their significance will be magnified tremendously once we have a treatment for Alzheimer's that can actually alter the course of the disease.
Q. Can you explain what some of these new tests (brain scans and testing cerebrospinal fluid) involve?
Dr. Press: The two tests are similar in that both take advantage of the advances we've made in understanding the underlying changes that occur in the brain when a person has Alzheimer's. They allow us to detect whether mild memory troubles are the beginning of Alzheimer's or not. Neither test is 100% accurate, but it's very close for people who are demonstrating some mild cognitive impairment.
Q. Does this mean that people without any obvious symptoms of Alzheimer's can now have brain scans and other tests that would indicate if they will develop Alzheimer's?
Dr. Press: No, it's too early for that. At this point we aren't ready to start screening people who aren't exhibiting any symptoms yet....but it may be closer then we thought even five years ago.
Q. Since there's no really effective treatment for Alzheimer's, what is the benefit of being diagnosed earlier?
Dr. Press: Our message is one of optimism. For people exhibiting some mild cognitive impairment, there's a good chance any testing will be negative, so they can be reassured.
For those with a positive test, the research into lifestyle intervention is making a lot of headway.
There's now a great deal of evidence that staying physically and mentally active can slow down the progression of Alzheimer's. Put another way, if there was a drug that delivered the same benefits to Alzheimer's patients as mental and physical activity, people would buy stock in it!
Q. Some experts are saying that the number of people diagnosed with Alzheimer's will double or even triple if these guidelines go into effect. What do you think about that?
Dr. Press: For people who are experiencing some impairment, it's a difficult decision. Each patient needs to have a conversation with their physician and weigh the pros and cons. Some will chose to pursue advanced testing, and some will wait, and good arguments can be made on both sides.
For patients with mild cognitive impairment, we're still in a bit of a gray area, but for people who want to get tested, we can say with a high degree of certainty if they will develop the disease. And that means they can receive treatment earlier and potentially slow down the development of the disease.
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Posted September 2010