The role of estrogen replacement therapy in Alzheimer's disease

Multiple factors appear to contribute to the expression of Alzheimer's dise ase (AD). About 30% of cases of dementia of the Alzheimer's type (DAT) can be attributed to genetic factors. These observations raise the possibility of identifying multiple interventions that may modify the disease process a nd, therefore, the clinical expression of the dementia. Prominent among fac tors 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 dis eased vessels, including blood flow in regions of the brain affected by AD. Estrogen also has direct effects on neuronal function that may play an imp ortant role not only in the preservation of neurons but in the repair of ne urons damaged by the disease process. These effects of estrogen on the CNS suggest that the hormone may be effective not only in the prevention of dem entia but also in its treatment. Given the distressingly high prevalence of AD among older women and the exorbitant social and economic costs associat ed with this disorder, a true risk reduction on the order of one-third to o ne-half, as suggested by several recent analytical studies, would be of tre mendous public health importance. (C) 2001 Elsevier Science Ireland Ltd. Al l rights reserved.