For many years doctors recommended hormone therapy (HT) for menopausal and post-menopausal women whether or not they were having difficulty with menopause-related symptoms (hot flashes, insomnia, mood swings). The intention was to prevent diseases that tend to increase after menopause, primarily heart disease and osteoporosis. Then in 2002, the health-care establishment was rocked by some pretty impressive data from a large, long-term study (the Women’s Health Initiative or WHI) indicating that HT not only doesn’t reduce the risk of heart disease, it increases the risk, and increases the risk of breast cancer, ovarian cancer and dementia as well, it seems.

If you follow the health news, this is an old story. But the part of the story that seems to be missing in much of the discussion is why physicians were prescribing this stuff so wantonly before the WHI data was crunched. Did the new study contradict earlier ones that had suggested that HT was good for preventing heart disease and other diseases? Well, no, not really.

The main reason your doctor prescribed HT to prevent these diseases was because it made some kind of logical sense. That was pretty much it. The reasoning went something like this: The incidence in women of most of these diseases increases after menopause. Levels of certain hormones drop after menopause; therefore, replacing these hormones ought to take care of the problem.

It sounds almost too simpleminded to be science, doesn’t it? And it turns out it was.

The situation is far more complicated, and teams of scientists have been busy for the past six years trying to figure out what really is going on with hormones and post-menopausal disease. Sherlock Holmes could have warned them that theorizing in advance of the facts is a capital error.

Avery Hurt is a health and science journalist. Her work appears regularly in national publications such as: Better Homes and Gardens, Newsweek and The New Physician. She is author of Bullet With Your Name On It: What You Will Probably Die From And What You Can Do About It (Clerisy Press, 2007) and Don’t Worry, I’m Not Contagious: Your Guide to Staying Healthy in an Infectious World, due out from Clerisy, fall 2008. She is at work on her third book, on alternative medicine.