Participants in the McGill University study who had been taking one of the selective serotonin reuptake inhibitors, or SSRIs, for at least five years had twice the risk of wrist, ankle, hip and other fractures compared with those not prescribed the drugs.
Daily use of SSRIs was also associated with a four per cent reduction in bone mineral density of the hip and 2.4 per cent of the lower spine, researchers found. The risk of falling was also higher among those taking the pills, which can cause a drop in blood pressure and fainting in some people.
"Depression is common in the elderly, and the elderly population is increasing in Canada and most of the western world,'' said Dr. David Goltzman, a Montreal endocrinologist and senior author of the study, published Tuesday in the Archives of Internal Medicine.
"So depression is increasing as the population ages and the use of SSRIs is increasing at a phenomenal rate,'' Goltzman said, noting that prescriptions for the medications soared by more than 30 per cent between 2000 and 2004.
"And that puts a lot of people at increased risk for fractures over and above the risk that they already have as a result of the fact that they're aging and are taking other medication which may also predispose to osteoporosis.''
But Goltzman stressed the findings do not mean that people should stop taking the antidepressants.
"I think that if they need an SSRI, if their physician feels that they need it to treat their depression . . . they need to be treated with the appropriate medication,'' he said. "It just means individuals should be aware this is a side-effect and they should probably also take general steps in order to prevent osteoporosis.''
Those steps include engaging in weight-bearing exercise, eating a diet rich in calcium and vitamin D, and avoiding smoking and alcohol.
Goltzman also suggests that older patients should have their bone density tested when they begin taking an SSRI and again after they have been on the drug for a period of time to see if their bones are thinning.
The study tracked 5,008 Canadians aged 50 and older for five years, including 137 who reported using SSRI antidepressants daily. In this smaller group, 18 people or 13.5 per cent had fractures during the study period, compared with 317 people with fractures, or 6.5 per cent, among 4,871 who didn't take the pills.
The research is part of the much larger, 10-year Canadian Multicentre Osteoporosis Study (CAMOS) funded by the Canadian Institutes of Health Research, drug companies that include Eli Lilly Canada and Merck Frosst Canada, the Dairy Farmers of Canada and the Arthritis Society.
Dr. Robert Josse, director of the Osteoporosis Centre at St. Michael's Hospital in Toronto, said the SSRI study provides "an important observation which is actually consistent with all the other data that exists.''
Even without SSRI use, an estimated one in four women and one in eight men over age 50 will develop osteoporosis; the risk of an associated fracture is 40 per cent for women and 15 per cent for men, said Josse, who was one of the investigators for the overall CAMOS study but had no involvement in the SSRI portion of the research.
"One has to be doubly vigilant in those people who anyway merit evaluation for osteoporosis,'' he said. "And amongst the questions we're particularly interested in and we should add to our risk factor profile is the use of SSRIs.''
Dr. David Healy, an expert in psychopharmacology at the University of Wales College of Medicine, said researchers are finding more and more side-effects associated with SSRIs, which he believes are vastly over-prescribed.
Previous research has shown that the drugs may increase the risk of bleeding in the gut and brain (a cause of stroke), have been linked to possible birth defects when women take the medication during pregnancy and may induce suicidal thoughts in some people, he said.
Furthermore, pre-marketing clinical trials of the medications show that the proportion of subjects who responded to pills containing active drug (50 per cent) was only slightly higher than the proportion who reported feeling better after taking dummy pills (40 per cent), said Healy. That suggests that for many patients, depression can resolve on its own over time or through discussion with a doctor or therapist, he added.
"But given that actually so few people comparatively are specifically helped by the drug, then it seems to me that people need to be informed about all of the risks so that they can work out whether this is a risk that they're happy to take,'' said Healy, who does prescribe the drugs to patients under certain circumstances.
In a statement responding to the study, the maker of Zoloft called depression "a serious problem in the elderly that is under-diagnosed and under-treated.''
"SSRIs are an important option for the treatment of depression in this population,'' Pfizer Inc. said. "As the authors note, the risks must be balanced against the benefits gained by the treatment of depression.''
