Therapeutic frontiers in Alzheimer's disease.

Alzheimer's disease (AD), the most common type of primary degenerative dementia, is the leading cause of cognitive impairment in the geriatric population. It is a devastating illness, both to the patients and the families involved. Although much research continues to be conducted, the etiology and effective treatment for the disease remain to be found. One of the primary hypotheses of the disease is that the cognitive decline of AD involves the loss of related cholinergic neurons. Although the cholinergic theory is still valid, efforts aimed at increasing levels of acetylcholine have yielded disappointing results. Currently, in the United States, several drugs are in various stages of development for the treatment of AD. The mechanisms of these agents include cerebral protectants, enhancers of neuronal signal amplification, tonic stimulation, and nerve growth factors. Other avenues being investigated include the development of novel drug delivery systems to enhance CNS concentrations of therapeutic agents.