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investigational in U.S.
Primary Medical Role:
Stimulate secondary sexual characteristics. Also exert
systemic effects such as growth and stimulation of long
bones. Estrogen replacement for post-menopausal women, to
protect against osteoporosis, heart disease, and other
Role in Alzheimer's Disease:
Several epidemiological studies suggests the use of
estrogen in postmenopausal women may delay the onset or
risk of AD.
It has both antioxidant and anti-inflammatory effects and
enhances the growth of select neurons that release
acetylcholine. Role not clearly known yet in the context
of Alzheimer's disease, but is thought to enhance growth
of neurons in the basal forebrain, and may have a direct
effect on beta amyloid. Estrogen may improve
lipoprotein/lipid metabolism. Developmentally, estrogen
plays an important role in neuron growth and survival.
Absolute contraindications: pregnancy, breast or
endometrium tumor (risks of causing cancer nil/low for
breast cancer, and has been associated with endometrium
cancer when taken as unopposed estrogen only), undiagnosed
genital bleeding, active liver disease.
Relative contraindications: thromboembolic disease,
thrombophlebitis, uterine leiomyomata, history of liver
disease, diabetes mellitus, porphyria, hypertension.
Definite: Nausea, breast enlargement/engorgement,
endometrial hyperplasia, bleeding, endometrial cancer,
(occasional:) jaundice. Controversial: Breast cancer,
migraine headache, thromboembolism, hypertension.
Evidence pro its efficacy:
Recent prospective cohort studies provide strong evidence
of estrogen's effect in reducing risk of AD. These studies
consistently show a risk ratio of .4-.5 or less,
independently of ApoE genotype, ethnicity or demographic
factors. The incidence of AD among 75-year-olds is 8.4%,
but only 2% among women on ERT.
Evidence con its efficacy:
An article published in 1999 reviewed that the treatment
trials published since then have methodological problems
that prohibit definite conclusions on the relationship
between HRT and cognitive decline and dementia.
See Research News: Estrogen does not affect AD progression.
For a comprehensive analysis of how hormone
replacement therapy affects risk of AD see AlzRisk.
This record was last updated December 6, 2011.
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