Scanning for Alzheimer’s Disease

Norm Foster Photo: Gregory Fox

Alzheimer’s is a disease that takes a terrible toll on the memories and lives of millions of adults and their families each year. Unfortunately, there is no definitive test for Alzheimer’s disease, and other disorders can mimic its symptoms. New drugs and therapies can slow the spiral of memory loss and behavior changes in Alzheimer’s patients, but they work best if the disease is diagnosed and treated early.

U-M neurologists, working with researchers at three other universities, are evaluating positron emission tomography, or PET scanning, as a diagnostic aid in Alzheimer’s disease. Norman Foster, M.D., who leads the research team, says initial results from the study show PET scanning can help physicians differentiate Alzheimer’s disease from other neurodegenerative disorders.

PET scans show activity in different parts of the brain and how each part is reacting to disease. Brain activity — or the lack of it — is what matters in Alzheimer’s disease, says Foster, a professor in the Department of Neurology in the U-M Medical School. Foster directs the Cognitive Disorders Clinic in the U-M Geriatrics Center and is the associate director of the Michigan Alzheimer’s Disease Research Center. He is also a senior research scientist at the U-M Institute of Gerontology.

Researchers have tried other medical imaging techniques to detect the disease, with disappointing results. Magnetic resonance imaging (MRI) and computed tomography (CT) scans can rule out other disorders, but they can’t positively detect Alzheimer’s. Based on the U-M study and other evidence, Foster feels that early diagnostic testing with PET could become common practice within a few years, and will help physicians choose the best treatment for their patients.

“In some cases, memory loss isn’t the first symptom,” says Foster. “It could be behavioral or language changes, or difficulty with everyday activities. All symptoms can be caused by different conditions requiring different kinds of treatments and may or may not respond to the same medications.

“PET imaging has a great advantage because it shows specific patterns of brain activity, which differ in normal aging, Alzheimer’s disease and other kinds of dementia. And we understand from PET scans which parts of the brain are most damaged in different disorders and how these changes relate to patients’ symptoms.”

Other universities participating in the study are the University of California-Davis, the University of Pennsylvania and the University of Washington. Funding was provided by the National Alzheimer’s Coordinating Center, part of the National Institute on Aging.

—KG

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NIH Alzheimer’s Disease Referral and Education Center