Antidepressants May Up Fracture Risk
Drugmaker Says Cause-Effect Isn't Proven
Jan. 22, 2007 -- Daily use of certain antidepressants doubles the risk of bone fractures in adults 50 and older, a new study shows.
"Other studies have pointed to this [link], but our study confirms it," says David Goltzman, MD, one of the study's authors. Goltzman is director of the Centre for Bone and Periodontal Research at McGill University in Montreal.
The antidepressants studied are a class known as selective serotonin reuptake inhibitors, or SSRIs. It includes such drugs as Prozac and Paxil.
Low levels of the brain chemical serotonin are associated with depression, and the drugs are thought to work by making serotonin more available.
SSRIs and Fracture Risk
Goltzman and his colleagues evaluated 5,008 adults 50 and older; the average age was 65.
They followed them for more than five years to see if they experienced "fragility" fractures -- the type suffered from relatively minor traumas such as falling out of bed.
Daily use of SSRIs was reported by 137 participants.
Even after the researchers adjusted for factors known to increase the risk of fractures -- such as falls, low bone density, and physical inactivity -- the adults on SSRI antidepressants had twice the risk of fracture than those not on such antidepressants.
X-rays confirmed the self-reports of fracture.
"In the SSRI group, there were 18 X-ray confirmed fragility fractures out of 137 people, or 13.5%," says Goltzman.
"In the non-user group, there were 317 X-ray confirmed fragility fractures out of 4,871 people, or 6.5%," Goltzman says.
Five SSRIs were used by study participants; besides Prozac and Paxil, they used Celexa, Luvox, and Zoloft.
How SSRIs May Boost Fracture Risk
The antidepressants may boost risk of fracture, Goltzman says, because of their effect on bone physiology. Serotonin recently has been found to be important in bone physiology.
One animal study, for instance, found that "if you alter the ability of the bone to use serotonin, you will get a reduction in bone density," Goltzman says.