Popular antidepressants make elderly bones fragile

Jun 27 2007

Two newly released studies have come out in support for the growing body of evidence that the most popular drugs used to treat depression may contribute to fragile bones in elderly people.

The research looked into a class of antidepressant drugs called selective serotonin reuptake inhibitors (SSRIs), which are taken by millions of people worldwide.

Many elderly people are prescribed SSRIs, which include the popular Prozac.

Prozac, which is known generically as fluoxetine is produced by drug company Lilly and accounts for more than 60 percent of U.S. antidepressant drug prescriptions.

Both teams of researchers found that older men and women taking SSRIs had more bone loss than those not taking the drugs; a drop in bone mass can lead to osteoporosis and bone fractures.

One team led by Dr. Susan Diem of the University of Minnesota tracked 2,722 women, average age 78, including 198 SSRI users; they measured their bone mineral density over a five years period and they found that those taking the antidepressants experienced a density decrease at the hip of 0.82 percent per year, compared to 0.47 percent per year among those not taking them.

However the research team say they cannot definitively determine whether the SSRIs are the cause of the increased rates of the bone loss or whether the it is due to other differences between SSRI users and nonusers.

For example users of such drugs may be less physically active than people not using them.

The second team of researchers led by Dr. Elizabeth Haney of Oregon Health & Sciences University in Portland tracked 5,995 men, average age 74, including 160 who used SSRIs.

They found that bone mineral density at the hip was 3.9 percent lower among SSRI users and 5.9 percent lower in the spine in than men not taking antidepressants.

When the team compared the results with other antidepressants they found no apparent effects on hip or spine density measurements between men who took tricyclic antidepressants or a third type of antidepressant called trazodone and those who took no antidepressants.

An earlier study by researchers from McGill University in Montreal, also found that older adults taking SSRIs had double the risk of a bone fracture compared to those not taking the drugs.

The researchers say SSRIs inhibit a protein that transports serotonin, a chemical messenger involved in sleep and mood; the protein has also been discovered in bone, raising the possibility the drugs may affect bone strength.

The researchers say the studies raise some concern about people taking SSRIs and whether they may need additional screening or extra protection for their bones.

The studies appear in the Archives of Internal Medicine, a publication of the Journal of the American Medical Association, and were funded by the National Institutes of Health.