The role of estrogen in the treatment of Alzheimer's disease.

Multiple factors appear to contribute to the expression of Alzheimer's disease (AD). About 30 percent of cases of dementia of the Alzheimer's type can be attributed to genetic factors. These observations raise the possibility of identifying multiple interventions that may modify the disease process and, therefore, the clinical expression of the dementia. Prominent among factors that may contribute to dementia and, specifically, to dementia of the Alzheimer's type is cerebral vascular disease. Estrogen is a potent factor that not only prevents vascular disease but also improves blood flow in diseased vessels, including blood flow in regions on the brain affected by AD. Estrogen also has direct effects on neuronal function that may play an important role not only in the preservation of neurons but in repair of neurons damaged by disease process. These effects of estrogen on the CNS suggest that the hormone may be effective not only in the prevention of dementia but also in its treatment. The results of clinical trials, reviewed in this presentation, are very promising but are limited by the paucity of subjects and often the lack of adequate controls. Larger, randomized, placebo-controlled trials are needed to definitively establish the efficacy of estrogen in the treatment of dementia of the Alzheimer's type.