ROANOKE TIMES
Copyright (c) 1996, Roanoke Times
DATE: Thursday, March 21, 1996 TAG: 9603210046
SECTION: NATIONAL/INTERNATIONAL PAGE: A8 EDITION: METRO
SOURCE: THE BOSTON GLOBE
Brain scans of people at high risk of Alzheimer's disease have yielded the first direct evidence that brain damage begins long before the disease causes obvious mental impairment, according to a new study.
Researchers say the scans provide a valuable new tool for testing drugs to fight Alzheimer's, showing quickly whether a treatment can slow or stop brain deterioration.
The scans, known as positron emission tomography, or PET scans, were carried out on men and women aged 50 to 65 who were genetically predisposed to Alzheimer's. The scans detected abnormally low brain activity in several areas of the brain where nerve cells had died. But the subjects showed no sign of memory loss or thinking problems - the hallmarks of Alzheimer's - during psychological and neurological testing.
The scientists, led by Dr. Eric Reiman of Good Samaritan Hospital in Phoenix and the University of Arizona in Tucson, said they are monitoring the volunteers to see if they develop Alzheimer's.
They cautioned that PET scans are a research tool, not a screening test. The expensive scans cannot predict with certainty whether or when someone will develop Alzheimer's, the researchers said, and in any case no treatment is available.
Alzheimer's disease, the most common form of dementia, affects some 4 million Americans and is the fourth-leading cause of death. People with Alzheimer's progressively lose short-term memory and other cognitive skills, eventually becoming totally disoriented and bedridden. The disease is ultimately fatal.
The study subjects were chosen because they have an unusual genetic trait - the ApoE 4 genotype - that is associated with a 90 percent chance of developing Alzheimer's. Scientists think people with this form of the ApoE gene have a defective repair mechanism in their nerve cells.
Dr. Zaven Khachaturian, a leading Alzheimer's specialist and director of the Ronald and Nancy Reagan Research Institute of the Alzheimer's Association, called the findings exciting.
``The work has many implications, and one of them is confirmation of a growing body of evidence that the disease starts many years before we actually see the clinical picture,'' he said. Because of the long delay in onset of symptoms - perhaps 20 or even 40 years, scientists say - Alzheimer's specialists hope to develop drugs that could halt or delay the nerve-destroying process before it interferes with memory or thinking.
LENGTH: Medium: 53 lines ILLUSTRATION: GRAPHIC: graphic - Alzheimer's detection APby CNB