Aberrant plasticity in Alzheimer's disease.

Alzheimer's disease (AD) is a region-specific degenerative disease that mainly impairs the temporal and parietal lobes, with preservation of the frontal lobes until advanced stages of disease. Since [11C]diacylglycerol PET facilitates examination of loci exhibiting plasticity, it was performed in eight patients with AD and six age-matched normal control subjects to evaluate frontal lobe function. [11C]Diacylglycerol tomograms obtained from patients with AD demonstrated strong spotty incorporation of [11C]diacylglycerol mainly in the frontal association areas. However, [18F]fluorodeoxyglucose tomograms exhibited region-specific findings such as decreased CMRGIc in the parietotemporal association areas, which are involved in impairment of cognitive function. The strong spotty incorporation of [11C]diacylglycerol suggested a compensatory plastic process in the frontal lobes in response to involvement by Alzheimer's disease of the posterior association areas.