August 10th, 2010
01:59 PM ET
By Dr. Sanjay Gupta
Even back when I was a medical student, we were taught Alzheimer’s disease (AD) began to cause damage in the brain years, perhaps decades before one’s memory started to fade.
The big question, of course, was how could you possibly screen for the disease before problems emerged? As things stood for a long time, the only way to know for sure if someone had AD was at the time of autopsy. In fact, the disease is named after Alois Alzheimer, a neuropathologist, who in 1906, diagnosed the disease by using special stains of the brain after a patient’s death.
Over the years, there have been sophisticated tests such as PET and MRI scanning, which can help diagnose a patient, but are often better at excluding other causes of memory loss rather than confirming early AD. In short, there has been no great screening test for Alzheimer’s disease.
That may all start to change today, based on a new study from the Archives of Neurology. The authors have conducted a study showing a spinal-fluid test can be nearly 100 percent accurate in identifying patients who have mild memory loss now, and will go on to develop AD.
Think about that for a second. I have seen so many patients with mild memory loss who ask the question – is this the beginning of Alzheimer’s disease? The truth is, as a medical community – we were not sure. This test could provide that answer.
The study of patients in their seventies, included 114 patients with normal memory. 200 had mild cognitive impairment and 102 had been diagnosed with Alzheimer’s disease. All of them underwent a spinal tap to collect cerebrospinal fluid (CSF), a procedure that costs anywhere between $300 and $500. It involves putting a needle in the spinal sac in the lower back. Women who have had an epidural during labor have experienced a procedure similar to this.
Almost all the patients with AD were found to have a distinctive collection of protein in their CSF, a sort of AD signature. That is: The spinal tap was very good at confirming someone did in fact have the disease. But it was the group of people with mild cognitive impairment that provided the most striking findings. Nearly 75 percent of those patients in the study had the signature CSF findings, and every single one of those patients went on to develop AD within five years. Every single one of them.
In the third group, the patients with normal memory, around one third of those patients had the abnormal proteins, and the authors believe those people will develop AD memory problems one day as well.
This study, which will need to be duplicated, seems to indicate if you have an abnormal test result with the spinal tap, you will develop Alzheimer’s Disease. It is just a question of when. It is also important to point out that no one can say a normal test result necessarily puts you in the clear and some people may have slightly abnormal test results without developing AD.
Nearly 20 years after I finished medical school, we are on our way to an effective screening test. Still, I would be remiss if I didn’t point out that nowadays, there aren’t great options for prevention or treatment of Alzheimer’s disease. Sure, researchers are optimistic we will get there soon, but not as things stand now. So, the bigger question for a lot of people is: Even if the spinal tap becomes a proven, effective screening test for AD – “would you really want to know, if there isn’t much you can do about it?”
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Get a behind-the-scenes look at the latest stories from CNN Chief Medical Correspondent, Dr. Sanjay Gupta, Senior Medical Correspondent Elizabeth Cohen and the CNN Medical Unit producers. They'll share news and views on health and medical trends - info that will help you take better care of yourself and the people you love.