August 12, 2008

PET Scans May Help Detect Alzheimer's Brain Plaques

TUESDAY, Aug. 12 (HealthDay News) -- PET scans may provide doctors with a non-invasive method of detecting Alzheimer's disease-related brain plaques, Finnish researchers say.

Currently, the only reliable way to assess the presence of such plaques is through analysis of brain tissue samples obtained when a patient is alive or after death. In their study, University of Kuopio researchers examined 10 patients without severe dementia who'd undergone a biopsy of their brain's frontal cortex to check for normal-pressure hydrocephalus, an abnormal increase of cerebrospinal fluid in the brain.

Cognitive impairment is a symptom of both normal-pressure hydrocephalus and Alzheimer's, and 22 percent to 42 percent of patients with symptoms of normal-pressure hydrocephalus have brain lesions characteristic of Alzheimer's disease, according to background information in a news release about the study. The biopsies showed that six of the study participants had Alzheimer's-related beta-amyloid brain plaques.

For this study, all 10 patients were injected with a marker called carbon 11-labeled Pittsburgh Compound B ([11c]PiB) before having a 90-minute PET scan. The patients with beta-amyloid plaques had a higher uptake of the marker in certain brain areas than patients without the plaques.

"The study supports the use of [11C] PiB PET in the evaluation of beta-amyloid deposition in, for example, mild cognitive impairment, Alzheimer's disease or normal-pressure hydrocephalus," the researchers wrote.

"Large and prospective studies are required to verify whether [11C]PiB PET will become a tool in diagnosing Alzheimer's disease. Another potential use of [11c]PiB would be the quantitative monitoring of beta-amyloid deposits in the brain in subjects under treatment in pharmaceutical trials of early Alzheimer's disease targeting amyloid accumulation," they added.

The study was published online this week in the journal Archives of Neurology and was expected to be in the October print issue of the journal.

More information

The Fisher Center for Alzheimer's Research Foundation has more about Alzheimer's disease diagnosis.

-- Robert Preidt
SOURCE: JAMA/Archives journals, news release, Aug. 11, 2008
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