Author Affiliations: Departments of Psychiatry and Behavioral Sciences, and Neurology, Keck School of Medicine, University of Southern California, Los Angeles.
Alzheimer disease (AD) increases exponentially with age, with an annual
incidence of approximately 0.08% at age 60 to 64 years, and more than doubling
every 5 years to an incidence of 0.7% at age 75 to 79 years and 1.4% at age
80 to 85 years.1 Approximately 43% of people
with AD are between 75 and 85 years.1 A substantial
number of observational studies have suggested that hormone therapy decreases
incidence or delays onset of dementia, primarily AD.2- 7 Laboratory
studies have shown that estrogen receptors are present on cholinergic neurons
and have neurotropic, antioxidant, and anti-inflammatory effects.8,9 Estrogen deficiency in middle age has
been postulated to account, at least in part, for the somewhat higher incidence
of AD in women than men and may constitute a risk factor for AD.
Schneider LS. Estrogen and DementiaInsights From the Women's Health Initiative Memory Study. JAMA. 2004;291(24):3005-3007. doi:10.1001/jama.291.24.3005