Evidence is growing that people taking the common antidepressants known as selective serotonin reuptake inhibitors (SSRIs) may be at risk for thin bones, reports the August 2009 issue of the Harvard Mental Health Letter.
In the past few years, well-designed studies have not only built a case for a biological link between bone and the brain, but also suggested that SSRIs may be particularly harmful to bone. Researchers have identified several possible mechanisms linking brain and bone. Studies have reported that depression elevates levels of both the stress hormone cortisol and various immune system cells that promote inflammation—changes that can harm bone. More recently, scientists have discovered that bone cells have receptors for various brain chemicals and may be responsive to changes in the brain.
For example, researchers have examined the impact of the mood hormone serotonin on bone health. SSRIs enhance serotonin activity by inhibiting a brain target known as 5-HTT. Investigators discovered that bone also has receptors for 5-HTT and wondered if SSRIs might therefore affect the bone. Laboratory research on this intriguing possibility has produced mixed results. Still, results from four of five epidemiological studies support the theory that SSRI use weakens bone and increases the chance of fracture—even after adjusting for other factors such as depression.
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