CHAT and Alzheimer disease: In post mortem brains of AD patients, accumulation of Aβ plaques has been found to have a strong inverse correlation with the expression of pre- and post-synaptic markers of cholinergic activity [8] and with the activity of acetylcholine (ACh) synthesizing enzyme choline acetyltransferase (ChAT) [9], thereby indicating that Aβ aggregates may have a causative role in cholinergic degeneration.