Emerging drugs for Alzheimer's disease. Mechanisms of action and prospects for cognitive enhancing medications.

This article has discussed various possible pharmacologic approaches to Alzheimer's disease. Despite generally encouraging results, no agent to date has proved to be dramatically effective. At present, treatment options are limited for the clinicians. Tacrine is available on the market. In the doses recommended, efficacy is modest, and side effects require vigilance in monitoring. Other cholinesterase inhibitors may be approved for clinical use in the near future but are likely to have similar modest clinical effects. L-deprenyl is marketed for Parkinson's disease but has not been adequately tested for efficacy in Alzheimer's disease. Newer drugs in earlier stages of development are generally intended to affect cholinergic systems in various other ways. The effects of these drugs on behavioral symptoms, in severe dementia, and in non-Alzheimer's dementia have not been adequately assessed. In the absence of known cause, and in the face of uncertainty regarding pathophysiology, efforts in the near future will focus on encouraging theoretical leads, sensible empiric trials, and symptomatic treatment research. Although public anticipation will be raised over each announced "breakthrough," only results from carefully conducted trials should be accepted.