Deficits of the cholinergic system in early AD.

Impairment of cholinergic neurotransmission is a well-established fact in Alzheimer's disease (AD) but there is controversy about its relevance at the early stages of the disease. In the recent years new techniques for in vivo imaging of key components of the cholinergic system in humans have developed. They are beginning to be applied to the very early stages of AD. Preliminary results suggest that there is early impairment of presynaptic receptors and acetylcholine esterase, the main degrading enzyme for acetylcholine, in cerebral cortex. The relation of these findings to neuronal function and post-mortem findings is being discussed.