Wednesday, July 7, 2010

Best tests to predict Alzheimer's identified


Combining a specific imaging test of the brain with a memory recall test appears to be the best predictor so far of Alzheimer's disease, U.S. researchers said.

The findings were culled from a large, ongoing study testing various brain imaging tests and biomarkers that aims to identify which patients with cognitive problems will progress to Alzheimer's disease.

"When you look at them all independently, they are all useful for predicting conversion (to Alzheimer's disease) and decline," said Susan Landau of theUniversity of California , Berkeley, whose study appears in the journal Neurology .

"The novel thing we did was put them all together in the same statistical model and compared them to see which were the most useful," she said in a telephone interview. For the study, researchers did memory and brain scan tests on 85 people with mild cognitive impairment who were part of the larger Alzheimer's Disease Neuroimaging Initiative study.

The tests included an episodic memory test, in which the patient must correctly remember a list of words. People were also tested to see if they had a variant of the APOE gene linked with Alzheimer's disease. Researchers did magnetic resonance imaging or MRI scans to measure brain volume in the hippocampus, the part of the brain responsible for learning and memory. They also measured proteins called tau and beta-amyloid linked with Alzheimer's disease. And they did an imaging test called positron emission tomography or PET to test for brain function by looking to see how well the brain uses glucose or sugar.

When they compared the effectiveness of each test in predicting conversion to Alzheimer's disease, two emerged as the best predictors. "People who had poorer scores on both of those tests were almost 12 times more likely to convert to Alzheimer's disease than people who were normal on those two," Landau said. Patients in the study were between the ages of 55 and 90 and were followed for an average of 1.9 years.

During that time, 28 of the 85 participants developed Alzheimer's disease. Landau, who wants to expand the study to confirm the findings, said she thinks they may be useful in helping doctors pick the best tests to predict which patients are most likely to progress to Alzheimer's disease within two to three years of testing.

Several teams are working on better ways to detect early-stage Alzheimer's disease in hopes of developing drugs that can fight it before it causes too much damage. Current treatments cannot reverse the course of Alzheimer's, a mind-robbing form of dementia that affects more than 26 million people globally.

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