Treatment of Alzheimer's disease: an evaluation of the cholinergic approach.

The cholinergic hypothesis claims that a decrease of acetylcholine (ACh) in the brain of patients with Alzheimer's Disease (AD) plays an important role in the deterioration of cognitive functioning. This hypothesis has led to extensive research in possible therapeutic approaches towards improving cholinergic transmission in AD patients. The different approaches have focused on the following six strategies: ACh precursors, ACh release, M1, M3, or M4 receptor agonists, M2 receptor antagonists, nicotinic agonists, and acetylcholinesterase inhibitors (AChEI). The aim of this review is to assess the effectiveness of the cholinergic approach for the treatment of AD.