A small company with a new brain scan for detecting plaque, the hallmark physical sign of Alzheimer’s disease, presented its results on Sunday at an international conference in Hawaii, and experts who attended said the data persuaded them that the method works.
Until now, the only definitive way to diagnose Alzheimer’s has been to search for plaque with a brain autopsy after the patient dies. Scientists hope the new scanning technique, described June 24 in The New York Times’s series “The Vanishing Mind,” will allow doctors to see plaque while the patient is still alive, improving diagnosis and aiding research on drugs to slow or stop plaque accumulation.
Neurologists have known about plaques ever since Alzheimer’s disease was first described in 1906. They are microscopic bumps made up of a protein, amyloid beta, appearing on the surface of the brain in areas involved with learning and memory. They are so characteristic of Alzheimer’s that they are required for a definitive diagnosis of the disease.
Of course, doctors do not wait for a brain autopsy to diagnose Alzheimer’s. They use memory tests and evaluations of patients’ reasoning and ability to care for themselves. Yet with autopsy, even doctors at leading medical centers have been wrong as often as 20 percent of the time: people they said had Alzheimer’s did not have plaque.
The scans were developed by a Philadelphia company, Avid Radiopharmaceuticals, and, independently, by Bayer and General Electric. They use a radioactive dye that attaches to plaque in the brain, allowing it to be seen with a PET scan.
Although the scans looked promising, the companies needed to show that what they revealed was the same as what a pathologist would see on autopsy.
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