Name:	Estrogen
Other Names:	Premarin™
Therapy Types:	pharmacological
Development Status:	investigational in U.S.
FDA Phase:	Discontinued
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 ills.
Role in Alzheimer's Disease:	Several epidemiological studies suggests the use of estrogen in postmenopausal women may delay the onset or risk of AD.
Pharmacological Role:	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.
Contraindications:	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.
Side Effects:	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.
Notes:	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.

References

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