(PSYCHIATRIC TIMES) - Results from a preliminary PET imaging study suggest that 80% of elderly people with mild cognitive impairment and evidence of beta-amyloid plaque in their brains will develop Alzheimer's disease.
Dr. Victor Villemagne, a dementia researcher from the Center for PET at Austin Hospital in Melbourne, Australia, drew this conclusion from a two-year study of 85 MCI subjects, Alzheimer's patients, and normal volunteers. His results were presented in June at the 2008 Society of Nuclear Medicine meeting.
Using carbon-11 Pittsburgh Compound B (PIB) PET imaging, Villemagne and colleagues affiliated with the University of Melbourne discovered that the disposition of intercortical beta-amyloid protein—a key indicator for the presence of Alzheimer's disease—changed only slightly after 21 months, but the changes were large enough to accurately show that 80% (12 of 15) of MCI subjects classified as PIB-positive would progress to Alzheimer's disease within two years. C-11 PIB PET was deemed 86% accurate for predicting the conversion to Alzheimer's disease, and it had a negative predictive value of 92% for ruling out its development among MCI subjects, Villemagne said. Apo-E genetic status, another possible indicator, was 78% accurate and had an NPV of 90%.
These results were among several important imaging findings pertinent to Alzheimer's disease diagnosis and characterization reported at the SNM meeting. Also related to MCI-to-Alzheimer's conversion was a study by Dr. Kai Kendziorra of the University of Zurich in Switzerland suggesting that a reduced prevalence of cerebral nicotinic acetylcholine receptors (nAChRs) in the brain can also single out which individuals with MCI will go on to develop Alzheimer's disease.
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