Estrogens and Alzheimer's disease

Prevalence rates of dementia range from about 5% in patients older than 75 years up to more than 10% in those older than 85 years, making dementia the most common disorder in old age. According to follow-up studies, most cases (50%-60%) could be characterised as Alzheimer's disease (AD). Clinically, mnestic and other cognitive dysfunctions represent the core symptoms of AD. It is well known that estrogens exhibit several psychotropic effects in humans and that a relative lack of endogenous estrogens may be involved in the pathogenesis of AD. Recent studies have provided evidence of systematic activation effects of estrogens on cerebral activity and cognitive function. Epidemiological studies have investigated the potential of estrogens to modify AD onset and progression. There was evidence for a beneficial effect of estrogen replacement therapy on AD with a reduction in incidence of approximately 50%. In addition, it has been speculated that estrogens may also exhibit beneficial effects on the clinical course of AD. The present article reviews current evidence in favour of the beneficial neurotropic and psychotropic effects of estrogens in AD.