Estrogen May Cut Rate of Alzheimer’s in Women : Health: Hormone recipients were 40% less likely to get the disease, USC study finds. Others had milder symptoms.
Post-menopausal women who receive estrogen replacement therapy to prevent bone loss and heart disease are less likely to develop Alzheimer’s disease and, if they do develop it, their symptoms are less severe, a USC researcher reported Tuesday.
In an 11-year study of 8,879 women at Leisure World in Laguna Hills, the researchers found that women who received estrogen were 40% less likely to develop the disabling disorder than women who did not take estrogen, Dr. Victor W. Henderson told a meeting of the Society for Neuroscience in New York City.
“This suggests that estrogen replacement might be useful for preventing or delaying the onset of this dementia in older women,” Henderson said. An estimated 15% to 18% of post-menopausal women--about 3 million--currently receive estrogen replacement therapy in the United States. Nearly 4 million elderly Americans have Alzheimer’s disease, which leads to loss of memory and an inability to care for oneself. The researchers have no data on the potential effects of estrogen in men.
In another study reported at the meeting, New Jersey researchers demonstrated in animals that administration of another female hormone, progesterone, can sharply reduce the extent of brain damage after concussions, such as those received in automobile accidents.
If this result with mice is replicated, human studies could begin very quickly because progesterone has no known serious side effects, said neuroscientist Robin L. Roof of Rutgers University in New Brunswick, N.J.
The two new studies demonstrate the previously overlooked importance of hormones in the brain and “could prove to be a boon to clinicians,” said Dr. Bruce McEwen of Rockefeller University in New York, who was one of the first to discover estrogen binding sites in the brain. “Estrogens are very important hormones for the brain.
Henderson’s results are stronger than prior hints of the effects of estrogen and worthy of further study, said JoAnn McConnell, senior vice president for medical and scientific affairs of the Alzheimer’s Assn. in Chicago.
The female body stops producing estrogen when the ovaries cease functioning at menopause, typically between the ages of 45 and 55. The absence of estrogen can produce a variety of symptoms, including hot flashes, mood swings, vaginal itching and increased urinary tract infections.
In the 1960s, physicians began prescribing estrogen replacement therapy to ease these symptoms. They soon discovered that the therapy also prevented or delayed osteoporosis, the bone thinning that leads to severe, even life-threatening, fractures.
More recently, researchers have discovered that estrogen replacement therapy can reduce the risk of cardiovascular disease by as much as 50%. A new study reported today in the journal Circulation found that protection extends well into the eighth decade of life.
Counterbalancing these benefits is an apparent increased risk of cancer. Studies have shown that estrogen replacement therapy can increase the risk of breast cancer by as much as 30%, perhaps even more in women with a family history of the disease. Early studies also showed an increased risk of endometrial cancer, but that risk has been largely eliminated by reducing estrogen doses and combining it with progesterone.
Henderson initially collected data from 253 elderly women retrospectively in a long-term study of aging and dementia--a loss of reasoning ability. He found that only 7% of the women with Alzheimer’s disease had undergone estrogen replacement therapy, compared to 18% of the women without the disorder.
Intrigued, he joined forces with Dr. Annlia Paganini-Hill of USC, who has been studying residents of Leisure World since 1981. They identified 127 women who died of Alzheimer’s or a related dementia and compared each with four other women who had similar birth and death dates and did not have Alzheimer’s.
They found not only that estrogen seemed to protect against Alzheimer’s, but also that higher doses provided more protection. Overall, the women who had estrogen replacement therapy were 40% less likely to develop Alzheimer’s than women who did not receive it, and those women who received the highest doses were 60% less likely to develop it. And those women who received estrogen and still developed Alzheimer’s performed better on mental tests than Alzheimer’s victims who did not receive the therapy.
Henderson cautioned that more studies need to be done with larger groups. In particular, he said, physicians should study whether estrogen can delay the onset of the disorder in women at high risk and whether it can improve mental functioning in women who have developed the disease.
“We haven’t proved anything yet,” he said in an interview. “We’ve just opened some doors, I think.”
In the progesterone study, Roof looked at edema, a swelling of the brain resulting from trauma, which causes the death of brain cells, accompanied by loss of cognitive, sensory and motor skills. Her initial studies had shown that male mice develop more edema than females because the females have higher circulating levels of progesterone.
Roof and her colleagues gave brain contusions, “much like those you might receive in a car accident,” to 24 male rats. Half the rats received progesterone injections every day for a week, while the other half received no treatment. Those rats that received the hormone performed nearly as well on mental tests as rats who had no contusions, while those who received no treatment performed much worse.
“Our findings are potentially important,” she said, “because progesterone is relatively safe and could be used in humans very easily.”
