Original article no longer available
The Ubyssey (University of British Columbia)
Issue date: 2/5/08 Section: Technology
VANCOUVER (CUP) — A new study on osteoporosis in Canadians has found a link between antidepressant drugs and higher instances of osteoporosis. The study focused on the use of a widely prescribed group of antidepressants known as selective-serotonin reuptake inhibitors (SSRIs) in patients over 50 years of age. It was found that patients taking SSRIs doubled their risk of incurring osteoporosis-related injuries, said David Goltzman, director of the Metabolic Bone Disease Centre at the McGill University Health Centre, and head of the study.
“SSRIs were associated with a two-fold risk of developing minimal trauma or osteoporotic fractures,” said Goltzman. “The absolute risk of developing fractures was 13.2 per cent in the individuals taking SSRIs and 6.6 per cent in the individuals not taking SSRIs.”
The study was carried out as part of the ongoing Canadian Multicentre Osteoporosis Study (CaMOS), which is co-ordinated through nine institutions across Canada. Researchers examined a cohort of patients 50 and older that has been monitored by CaMOS for the last 10 years.
The researchers were aware of other age-related factors associated with osteoporosis, but were still able to establish a link with SSRIs after accounting for other possible variables.
“Increased age, female sex, sedentary lifestyle, are all known to predispose to osteoporosis, including osteoporosis in the CaMOS population,” Goltzman explained. “Because we had recorded all this data in the CaMOS database as well as data on the bone density of these people, their frequency of falls, we were able to correct for all of this.”
He added that SSRIs were still associated with an increased risk of low-trauma fractures.
Goltzman also made reference to studies involving insurance company records of medications and injuries.
“Previous studies in administrative databases, [such as] large databases accumulated usually by governments or insurance companies to track health care usage and costs, had indicated that there was a relationship between SSRIs and osteoporosis,” he said.
While the nature of the SSRI link is unknown, there are several theories that researchers are considering.
“SSRIs alter serotonin transport into cells and previous work in vitro and in animals had found that serotonin transport into bone cells and action in bone cells seems to be important to make bone,” Goltzman said.
CaMOS is also theorizing serotonin’s role as a neurotransmitter and the potential for it to affect the sympathetic nervous system, which governs the mobilization of the body in times of stress.
Jerilynn Prior, professor of endocrinology and metabolism at the University of British Columbia and a research member of CaMOS, said that inhibiting neurotransmitters from the sympathetic nervous system, like epinephrine and norepinephrine, improves bones.
“Norepinephrine is hard on bones,” Prior said. However, she said that serotonin’s specific effect on the system is still unknown.
Prior added that certain behavioural patterns among depressed patients that could contribute to osteoporosis and associated bone fractures, such as inattentiveness to one’s surroundings, as well as increased levels of stress-related hormone cortisol, which can promote loss of bone density and hinder bone growth.
However, she added that depressed patients taking SSRIs instead of other antidepressant formulations showed a markedly higher incidence of osteoporotic bone fractures.
“The associations that we found suggests that SSRI use apart from depression itself increases low bone density,” she said. “There’s something specific to the biochemistry of SSRIs.”
While all of this seems to paint a rather bleak picture for users of SSRIs, there are many lifestyle adjustments to one’s lifestyle that can lower their risk.
According to Marcel Dvorak, head of the academic division at UBC’s department of orthopedics in the faculty of medicine, having a healthy diet and getting enough exercise are the most important preventative measures.
“If you maintain a healthy, normal diet, and if you maintain a high level of physical activity, then those are the best ways to ensure the best [outcome].”
Dvorak also said that high bone mass needs to be maintained at every stage of life, not just in old age.
“If you think of your bone mass as a bank, and during your life, you’re making deposits into that bank and you’re building up your bone mass, at a certain point that bone mass starts to diminish and wear away,” he said. “What you want to do is you want to get the best possible bone mass years, when your bone mass starts to diminish.”