Brain acetylcholinesterase activity in Alzheimer disease measured by positron emission tomography

Brain acetylcholinesterase activity was measured in 14 patients with Alzhei mer disease and 14 age-matched control subjects by positron emission tomogr aphy with a radioactive acetylcholine analogue. Kinetic analysis was perfor med to calculate k(3), an index of acetylcholinesterase activity. The k(3) values were significantly reduced in the neocortex, hippocampus, and amygda la of all patients with Alzheimer disease, suggesting a loss of cholinergic innervation from the basal forebrain. Most profound reductions of k(3) val ues were observed in the temporal (-30%) and parietal cortices (-31%), alth ough reductions of k(3) values were relatively uniform in the cerebral neoc ortex. This technique may be a powerful tool for early diagnosis of Alzheim er disease and also for therapeutic monitoring of acetylcholinesterase inhi bitors in Alzheimer disease.