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Science File

New Imaging Technique Detects Signs of Alzheimer's

Researchers use a dye and scan to find buildup on the brain without removing tissue.

January 24, 2004|Thomas H. Maugh II | Times Staff Writer

Pennsylvania researchers have found a way to identify brain abnormalities characteristic of Alzheimer's disease in living people, a discovery that will aid diagnosis of the disease and provide a way to monitor the efficacy of new Alzheimer's drugs.

"Until now, [the abnormalities] could only be shown at autopsy or by brain biopsy," said William Thies, vice president of medical and scientific affairs for the Alzheimer's Assn. "This is a significant advance for Alzheimer's research."

The abnormalities are called amyloid plaque, a buildup of protein that disrupts brain cells and may be one of the primary causes of Alzheimer's symptoms.

Previously, the only way to see amyloid has been by direct visual observation.

Dr. William E. Klunk of the University of Pittsburgh Medical Center has spent years looking for something that would bind to the amyloid. Ultimately, he settled on a slightly altered version of a dye called thioflavin-T, which crosses the blood-brain barrier and stains amyloid. He and Dr. Chet Mathis attached the dye to a radioactive marker that allows it to show up on a brain scan and sent it to Dr. Bengt Langstrom of Uppsala University in Sweden for testing.

They reported this week in the online version of the journal Annals of Neurology that the images -- obtained with a technique called positron emission tomography, or PET -- clearly showed the presence and amount of amyloid in 16 patients who had been diagnosed with mild cases of Alzheimer's.

The test showed no amyloid in the brains of eight of nine control subjects who did not have the disorder.

Small amounts of amyloid were found in the ninth control, a man in his 70s who was beginning to show vague symptoms of mental decline.

The next step will be to perform additional testing in healthy people and those with confirmed Alzheimer's.

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