Medical Health Encyclopedia

Osteoporosis is a disease of the skeleton in which bones become brittle and prone to fracture. In other words, the bone loses density. At age 65, about 30% of women have osteoporosis, and nearly all of them are unaware of their condition. After age 80, up to 70% of women develop osteoporosis. Osteoporosis is a major risk factor for fracture in the spine and hip. The lifetime risk of spinal fracture in women is about one in three and that for hip fracture is one in six. Furthermore, between 10% and 20% of women who experience a hip fracture die within a year and about 25% require nursing home treatment.

Click the icon to see an image of osteoporosis.

Experts are still puzzled by the extreme speed-up of bone breakdown (resorption) after menopause. Estrogen may have an impact on bone density in various ways:

• Estrogen's most important effect on osteoporosis appears to be prevention of bone break down (resorption). Some research suggests that estrogen may control the life span of osteoclasts, the cells responsible for bone breakdown.
• One study reported that part of estrogen's beneficial actions may involve maintaining normal levels of vitamin D, an important nutrient in bone protection.

Risk factors for osteoporosis include:

• Being tall and thin.
• Being Caucasian.
• Smoking.
• Taking thyroid hormone.
• Being sedentary.
• Early menopause or surgical menopause (removal of ovaries).

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Women at risk for osteoporosis should have a bone density test to measure their bone mass and then make a decision about treatment after consulting their physician.

Estrogen Loss and Mental Decline

Estrogen, the primary female hormone, appears to have properties that protect against the memory loss and lower mental functioning associated with normal aging. Among estrogen's effects on the brain are the following:

• Laboratory studies suggested that estrogen may help block production of beta-amyloid, the source of the sticky plaques found in Alzheimer's brains.
• Estrogen may trigger the temporary growth of nerve pathways in the memory portion of the brain.
• Estrogen may stimulate production of the neurotransmitters acetylcholine and serotonin, which are depleted in Alzheimer's patients.
• Estrogen also appears to smooth, relax, and open blood vessels, which may help blood flow in the brain.
• Estrogen is also an antioxidant. That is, it helps clean up free-oxygen radicals, the unstable particles thought to play a role in Alzheimer's.
• Studies have been mixed on the association between natural estrogen levels and mental functioning in older women. For example, one 2001 study reported no association between a higher risk for dementia and a longer reproductive life in women, suggesting that longer exposure to estrogen did protect against mental decline. On the other hand, a 2002 study reported poorer mental status in women with lower levels of estrogen.

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