In-vivo measurements of regional acetylcholine esterase activity in degenerative dementia: comparison with blood flow and glucose metabolism

Memory and attention are cognitive functions that depend heavily on the cho linergic system. Local activity of acetylcholine esterase (AChE) is an indi cator of its integrity. Using a recently developed tracer for positron emis sion tomography (PET), C-11-labeled N-methyl-4-piperidyl-acetate (C-11-MP4A ), we measured regional AChE activity in 4 non-demented subjects, 4 patient s with dementia of Alzheimer type (DAT) and 1 patient with senile dementia of Lewy body type (SDLT), and compared the findings with measurements of bl ood flow (CBF) and glucose metabolism (CMRGlc). Initial tracer extraction w as closely related to CBF. AChE activity was reduced significantly in all b rain regions in demented subjects, whereas reduction of CMRGlc and CBF was more limited to temporo-parietal association areas. AChE activity in SDLT w as in the lower range of values in DAT. Our results indicate that, compared to non-demented controls, there is a global reduction of cortical AChE act ivity in dementia.