Alzheimer’s disease (AD) is the leading cause of dementia in
the elderly and is characterized by the presence of extensive
plaque deposition and neurofibrillary pathology. A number
of clinical studies have suggested that estrogen therapy may
delay the onset or contribute to the prevention and/or attenuation
of Alzheimer’s disease (AD) [155–163, and 164 for review].
As reviewed by Henderson [165], 12 case-control and cohort
studies were conducted in the 1990s on estrogen use and
AD. All but two studies found a significantly reduced risk of
the incidence of AD in women who were estrogen users versus
nonusers. In fact, meta-analysis studies suggest overall
Alzheimer risk reductions of about 29–44% [161,162]. However,
several studies showed that estrogen treatment after
the disease process has started was generally unsuccessful
in ameliorating the decline in cognitive function in AD that
inevitably occurs over time [166–168], although there are dissenting
studies in the literature [169–171].