June 26, 2007 — -- Elderly people who take certain antidepressants may have something new to worry about: increased bone loss due to their medications.
Drugs like Paxil and Prozac, which are known as SSRIs, or selective serotonin reuptake inhibitors, may decrease bone density, according to a study released Monday in the Archives of Internal Medicine.
The drugs account for 62 percent of prescriptions to treat depression, suggesting that many people may be affected. But the study's authors say it's too soon to tell people they should stop taking their antidepressants.
"I would stress that people who are taking antidepressants should not stop taking them," said Dr. Susan Diem of the University of Minnesota, the study's lead author. "More work needs to be done to tell if drugs are having a direct effect on bone, or if something else is at work."
Researchers studied 2,722 older women for three years, measuring their total hip bone density periodically. At each visit, the participants brought all medications they had taken in the prior two weeks.
After adjusting for all other factors, Diem and her team noticed a difference in the bone density of women who took SSRIs. They were losing 0.82 percent bone density per year, compared with 0.47 percent loss per year in the group that wasn't taking SSRI antidepressants.
"Recently, scientists have described the presence of serotonin transporters in bone, leading to other work that says blocking serotonin in bone might impact bone health," Diem said. "We know that this is true for animals… So we decided to see if that has any impact in humans, since SSRIs work by blocking the serotonin transporters."
A related study of men, also released Monday, found that bone density in men who took SSRIs was an average of 3.9 percent lower than that of men who were not taking the antidepressants. Men taking other types of antidepressants did not see any difference in bone density.
"Every drug has risks, and we spend every day balancing risks and benefits," said Dr. Thomas Schwenk, chair of family medicine at the University of Michigan.
"The problem here is that depression may be discounted in its importance, and somehow be seen as less worthy of treatment in the face of risks such as this, when in fact it is one of the highest impact, most costly chronic diseases."
Depression affects as many as 40 percent of older adults, and major depression cost the U.S. economy an estimated $83.1 billion in the year 2000.
Moreover, some experts say antidepressants are not the only factor that may impact the loss of bone density with age and depression.
"The fact is that the lack of exercise that often accompanies depression would have a far greater effect than any presumed medication effect," said Dr. William McDonald, professor specializing in late-life depression at Emory University.
"It is also very difficult to make any conclusion about the amount of time spent depressed, or the actual compliance on antidepressants."
The study's authors agree that it would be premature to consider any changes in treatment for elderly people with depression now.
Instead, they say people who are concerned should speak with their physicians about lifestyle changes they can make, such as increasing exercise, changing their diets and taking calcium supplements.
"Depression is a serious problem in the elderly, and that's why I would not want people to overreact to these preliminary findings," Diem said.