Hormone Replacement Increases Risk of Dementia

Hormone therapy doubled the risk of Alzheimer's disease and other types of dementia in women who began the treatment at age 65 or older, according to a large study.

The findings are the latest of a string of studies showing that the supposed benefits of hormone therapy do not exist and that the hormones actually raise the risk of several serious disease.

The four-year study involved 4,532 women half of whom took placebos, and half who took Prempro, which is a combination of estrogen and progestin and the most widely prescribed type of hormone therapy.

Forty cases of dementia developed in the hormone group during the four years compared to 21 in the placebo group, leading researchers to say that there’s no reason for older women to take combination hormone therapy.

In terms of an annual rate, the findings indicate that for every 10,000 women aged 65 years and older who take hormones, 45 cases of dementia will develop each year, 23 of them due to the hormones.

Wyeth, Prempro’s manufacturer, plans to add a warning to the drug’s label about the increased risk of dementia.

Researchers noted that the number of cases per year is small and is no cause for alarm, but recommended that older women who are taking combination hormone therapy should decide with their doctors whether they should quit.

It is not known whether the findings apply to younger postmenopausal women or women who take other hormone combinations or estrogen alone.

Two other studies have found that combined hormone therapy has a negative impact on the brain and increases the risk of stroke.

Of the 2.7 million American women who take combination hormone therapy, 1.2 million use Prempro. The hormones were approved by the Food and Drug Administration (FDA) to treat menopausal symptoms like hot flashes and night sweats and to prevent the bone-thinning disease osteoporosis.

However, the hormones slightly increase the risk of breast cancer, strokes and heart attacks, so the agency recommends that women consider other treatments for osteoporosis and that they use the lowest dose of hormones for the shortest time possible.

Last year a large study was halted after findings indicated that the combination therapy caused a small but significant increase in the risk of invasive breast cancer. Many women stopped taking the hormones after the study came out--prior to the study about 6 million women were taking combination therapy.

However, many people still believed that the hormone therapy might protect the brain and help prevent Alzheimer’s disease.

The theory that estrogen might prevent Alzheimer's was based on earlier, survey-type studies suggesting that women on hormones had lower rates of dementia than women not on hormones. But those studies were not considered as reliable as the current study because they were smaller and did not contain control groups.

The current study suggests that any good effects the hormones may have on brain cells may be offset by harmful effects. Researchers are not certain how the combination therapy increases the risk of dementia but suggested that it increased the risk of blood clots and clogged blood vessels in the brain, which might injure brain cells and contribute to Alzheimer’s disease.

Numerous studies are being conducted to further assess the impact of hormone therapy on diseases such as osteoporosis, heart disease and Alzheimer's disease.

New York Times May 28, 2003