Nov. 23, 2001 Ever wonder whether your memory lapses might indicate something more serious? Now a non-invasive medical procedure can help you know for sure.
UCLA research shows that positron emission tomography (PET) scans of the brain can accurately detect early Alzheimer’s disease up to 95 percent of the time — leading to prompt medical treatment for the debilitating disease.
Reported in the Nov. 7 edition of the Journal of the American Medical Association, the UCLA team’s findings also show that PET is sensitive enough to predict whether persons experiencing age-related memory problems will or will not develop dementia in the future.
In the largest PET scan study of Alzheimer’s diagnosis to date, researchers evaluated 284 patients at eight academic centers in the United States and Europe between 1984 and 2000. The UCLA team pooled data from brain PET scans, clinical follow-up and autopsy findings to judge PET as a tool for detecting — and predicting — Alzheimer’s disease.
“We wanted to test the sensitivity of PET in evaluating the brain for the presence of Alzheimer’s disease and other dementias,” said Dr. Dan Silverman, principal investigator and UCLA assistant professor of pharmacology. “We found that PET opens a window into the living brain with a degree of accuracy matched only by autopsy.”
“Physicians can perform this procedure non-invasively on living patients and detect dementia early enough for clinical intervention,” he said.
Silverman and his colleagues used PET scans to map brain activity in 284 middle-aged and elderly adults being evaluated for dementia. After the scans revealed changes in brain activity, the UCLA team used the test results to predict the patients’ future cognitive abilities.
Physicians monitored 146 of the patients over two to nine years to determine whether or not they developed dementia. In the 138 other patients, physicians examined their brain tissue after death for signs of Alzheimer’s disease and related dementias. In each case, the UCLA team compared the patient’s final clinical outcome to its PET-based predictions.
Silverman and his colleagues found that PET accurately detected brain changes linked to Alzheimer’s and other dementia the vast majority of the time. For example: · PET correctly identified Alzheimer’s in 95 percent of the patients in the earliest stages of dementia. · PET accurately foretold the disease in 93 percent of the patients later diagnosed with progressive dementia. · PET correctly identified the presence of Alzheimer’s disease in 94 percent of the diagnoses later confirmed by autopsy. · PET accurately predicted whether patients would or would not develop Alzheimer’s disease in nearly 90 percent of all cases.
“PET’s ability to diagnose dementia in its earliest stage holds great significance,” Silverman said, “because medical management offers the most benefit during the initial period of decline.”
“This is the first study to evaluate a large group of patients for dementia through both PET and autopsy — the gold standard for Alzheimer’s detection,” said Dr. Gary Small, director of UCLA’s Center for Aging and co-author. “We are now in a more informed position to consider what role PET should play in the clinical evaluation of patients with symptoms of dementia.”
Pioneered by Dr. Michael Phelps, UCLA pharmacology chair, PET scans measure brain activity by revealing the amount of glucose metabolized in each region of the brain. A drop in metabolism indicates decreased activity in that region. Unlike other brain imaging techniques, PET scans can differentiate Alzheimer’s disease from the normal effects of aging.
“We believe that physicians can use PET to detect Alzheimer’s disease with high sensitivity and accuracy — even in its earliest stages,” Silverman said. “Physicians can also use the scans to reassure people that their symptoms are not due to Alzheimer’s or other neurodegenerative diseases that cause mental decline.”
Alzheimer’s disease afflicts nearly 10 percent of people older than 65. The condition often begins with mild memory lapses, then gradually advances to dementia — a progressive deterioration of memory, language and most mental functions. Alzheimer’s patients eventually become bedridden and require constant care. The United States spends roughly $100 billion on the disease per year.
The UCLA team collaborated with researchers at UC Davis, UC Berkeley, the National Institute of Aging, Duke University, University of Pennsylvania, New York University, Universite de Liege in Belgium and the Max-Planck-Institut fur Neurologische Forschung in Koln, Germany.
The study was supported by grants from the National Institute on Aging, the Alzheimer’s Disease Research Center of California, the U.S. Department of Energy, the Department of Radiology at Duke University and the Sidell-Kagen Foundation.
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