MINNEAPOLIS / ST. PAUL (June 25, 2007) — Researchers at the University of Minnesota report that older women who take a commonly prescribed class of antidepressants lose bone mass more quickly than women who are not on the medication.
A decrease in bone mass can lead to osteoporosis and eventually bone fractures; an estimated 10 million Americans have osteoporosis, 80 percent are women.
The study appears in the June 25, 2007 issue of the Archives of Internal Medicine, a JAMA/Archives journal.
The researchers compared bone mass in three groups of women: women on selective serotonin reuptake inhibitors (SSRIs); women on tricyclic antidepressants (TCAs); and women who were not taking any type of antidepressant medication.
Selective serotonin reuptake inhibitors (SSRIs) work by inhibiting the re-absorption of serotonin into cells. Serotonin is a neurotransmitter in the brain that is thought to affect mood. TCAs work through a different mechanism, affecting the levels of both serotonin and norepinephrine in the brain.
The reason the researchers examined this potential connection was that serotonin transporters, which are inhibited by SSRIs, are also found in bone.
“Further research is needed to determine the degree to which the medication is contributing to the bone loss,” said Susan Diem, M.D., M.P.H., first author on the study and assistant professor in the Department of Medicine “Other differences between women who take SSRIs and women who are not on SSRIs may explain the differences in bone loss that we observed.” She stressed that women should not stop antidepressant medication without speaking with their health care provider.
Diem and colleague Kris Ensrud, M.D., M.P.H., professor of medicine and senior investigator on the project, used data from the Study of Osteopathic Fractures, a multi-center study of postmenopausal women. Of the 2,700 women studied for this analysis, 7.3 percent were on SSRIs, 4.3 percent were on TCAs, and 88.4 percent were not taking antidepressants.
When the researchers adjusted for other factors that may have affected the study participants’ bone density, they still found the women on SSRIs lost more bone mass over time compared to the other groups.
Since women experience bone loss naturally as they age, next the researchers will look at whether younger women on SSRIs experience a similar bone loss. In addition, more research is needed to determine whether the amount of bone loss observed translates into an increase in fractures.
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