Recent 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, helping patients receive prompt medical attention and treatment.

According to the Nov. 7 edition of the Journal of the American Medical Association, the UCLA team also found that PET is sensitive enough to predict whether persons experiencing age-related memory problems will or will not develop dementia in the future. This non-invasive medical procedure can help people decide if memory lapses might indicate something more serious.

In the largest PET scan study of Alzheimer's diagnosis to date, the 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-ups, 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," explained 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 monitored 146 of the patients for a period of 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, and accurately foretold the disease in 93 percent of the patients later diagnosed with progressive dementia. In addition, PET correctly identified the presence of Alzheimer's disease in 94 percent of the diagnoses later confirmed by autopsy, and accurately predicted whether patients would or would not develop Alzheimer's disease in nearly 90 percent of all cases.

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.

"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."

"We believe that physicians can use PET to detect Alzheimer's disease with high sensitivity and accuracy -- even in its earliest stages," said Silverman. "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."

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.