June 24, 2008

Brain Scans Detect Alzheimer's Disease Quickly

TUESDAY, June 24 (HealthDay News) -- French radiologists report they've simplified a method of scanning the brain for signs of Alzheimer's disease, potentially making it easier to diagnose the mind-robbing condition.

It's too early for doctors to start routinely using the approach, but early tests are encouraging, said study author Olivier Colliot, a researcher from the Cognitive Neuroscience and Brain Imaging Laboratory at the Universite Pierre et Marie Curie in Paris.

Currently, the procedure required to diagnose the disease is "time-consuming and requires specific expertise," explained Colliot. "As a result, it hasn't become part of clinical routine. Our method allows performing this procedure automatically and within a few minutes."

According to the National Institutes of Health (NIH), an estimated 4.5 million Americans have Alzheimer's disease, and it's thought to affect one in 20 people between the ages of 65 and 74. The estimated rate goes up to nearly half among those 85 and older.

But diagnosing Alzheimer's disease isn't easy. The only way to be certain is to examine brain tissue after death. During life, doctors try to confirm an Alzheimer's diagnosis with a variety of tests and are right up to 90 percent of the time, according to the NIH.

One approach is to use MRI scans of the brain to determine whether brain tissue is shrinking.

This is a very recent development, Colliot said. Previously, doctors relied on MRI scans in the brain to detect tumors.

Alzheimer's shrinks the part of the brain known as the hippocampus, and MRI scans can pick up a problem. But the existing technique requires a radiologist to manually trace the contours of the brain, a process that can take an hour, Colliot said.

The approach is tedious, not highly reliable and not practical for wide use, said Dr. R. Nick Bryan, chairman of radiology at the University of Pennsylvania Health System.

The French researchers developed a technique that allows a computer to calculate the size of the hippocampus within minutes.

Colliot and colleagues tried their technique on 25 Alzheimer's patients, 24 patients with mild cases of cognitive impairment and memory loss, and 25 seniors who were healthy. They reported their findings in the July issue of Radiology.

The researchers found that the hippocampus was about a third smaller in the Alzheimer's patients than in the healthy ones and 19 percent smaller in those with cognitive impairment.

Doctors were able to correctly distinguish those with Alzheimer's' disease from healthy people 84 percent of the time.

Alzheimer's disease is not curable, but doctors can prescribe drugs to treat symptoms once they have a diagnosis, Colliot said.

At the moment, the new technique isn't ready for prime time, said Bryan. "A number of papers using different, but similar computer analytical approaches have been published, and there is no question that this will eventually be the preferred technique," he noted. "However, the different methods have not been sufficiently validated for routine use."

But once a technique is proven, it should help doctors diagnose Alzheimer's early and track whether medications are working properly, Bryan said.

More information

Learn more about diagnosing Alzheimer's disease from the U.S. National Institutes of Health.

SOURCES: Olivier Colliot, Ph.D., researcher, Cognitive Neuroscience and Brain Imaging Laboratory, Universite Pierre et Marie Curie, Paris; R. Nick Bryan, M.D., Ph.D., professor and chairman, Department of Radiology, University of Pennsylvania Health System, Philadelphia; July 2008, Radiology
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