WEDNESDAY, Dec. 21 (HealthDay News) -- Lack of estrogen in the brain is associated with Alzheimer disease, which could explain why women are more likely to develop the disease than men, according to a study of postmortem human brain tissue and transgenic mice published online Dec. 19 in the Proceedings of the National Academy of Sciences Early Edition.
Rena Li, M.D., Ph.D., of the Sun Health Research Institute in Sun City, Ariz., and colleagues measured estrogen levels in postmortem brains of 10 women with Alzheimer disease and 10 controls. They also crossbred APP23 transgenic mice, which are prone to developing Alzheimer disease, with mice lacking the estrogen-synthesizing enzyme aromatase to produce estrogen-deficient APP23 mice.
Estrogen levels were lower in the brains of women with Alzheimer disease (60% to 85%) than controls. Compared with the APP23 mice, the estrogen-deficient APP23 mice had less estrogen in the brain and more brain plaques consisting of extracellular beta amyloid peptide, a hallmark of Alzheimer disease. Plaques also accumulated earlier, at six months rather than 12 months, in the low-estrogen mice.
"Our results indicate that estrogen depletion in the brain may be a significant risk factor for developing Alzheimer disease neuropathology," Li and colleagues conclude.
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