Do antidepressant drugs improve bone health? No. In fact, just the opposite.

What’s Wrong With This Picture?

Which came first – the chicken or the egg?

That question is no longer a quandary, according to scientists who specialize in evolutionary genetics. They say the egg came first. But it wasn’t a chicken egg, it was an egg of some other type of bird, and it contained a DNA mutation that produced a bird that eventually evolved into the chicken.

Good enough. Just one question: Which came first – that other type of bird, or the egg of that other bird?

The evolutionary geneticists can get back to me later on that one. Meanwhile, let’s puzzle this one out: Which comes first – bone loss caused by depression, or bone loss caused by antidepressants?

Actually, this one won’t be as difficult to answer.

Sleight of hand

Take nearly 90 women (all premenopausal, under the age of 46) who have major depressive disorder (MDD), and about 45 women of the same age who don’t suffer from depression. Use a special x-ray technique to assess their bone density.

Results: Compared to subjects who aren’t depressed, the depressed subjects have significantly greater thinning of the bone in the femoral neck (the section of the femur that’s most vulnerable to fracture). Depressed subjects also have a significantly higher incidence of low bone mass in the lower back and lumbar spine.

The conclusion is obvious, of course: Low bone mineral density is more prevalent in premenopausal women with MDD, so (in theory) depression must be a risk factor for osteoporosis.

Before we go on, can you spot what’s wrong with this picture? It’s easy – just keep your eye on the money.

Leaping logic

Safe to say, a large majority of patients diagnosed with MDD end up taking antidepressants for extended periods.

In the study described above (funded by the National Institutes of Health and published last month in Archives of Internal Medicine), all of the MDD subjects were taking antidepressants. So does it seem more likely that their bone loss was prompted by depression, or prompted by antidepressant drugs?

In the Product Prescribing Information for Prozac, a list of “events” observed in clinical trials notes that osteoporosis was one of the side effects. It’s considered a rare side effect, but still, there it is. The Prozac web site also notes that the drug impaired bone development in early animal studies.

And yet, most of the reports about this study would have us believe that antidepressant drugs had no effect at all on subjects’ bone health.

Ivanhoe Newswire: “Although the depressed women were on anti-depressant medication, the study indicated that was not a factor in increased bone loss.”

Science Daily: “A previous study suggested that older adults taking antidepressants called selective serotonin reuptake inhibitors had more bone fractures than others. However, the current study showed that these medications were not linked to low bone mass in premenopausal women.” How did the current study demonstrate no link? Science Daily doesn’t open that can of worms.

Things start to get humorous with this from MedPage Today: “…the investigators noted that the usefulness of antidepressants for bone mineral loss in major depression should be evaluated.”

At first I thought I’d read that incorrectly, but then I came across this howler from HealthDay News: “It’s not clear what role antidepressants might play, but by relieving the depression, the drugs may also help bone mineral density, the researchers said.”

That’s an absurd leap of logic that only a drug company executive could love.

So what’s really going on here? Is the NIH kindly laying the groundwork for drug companies to sell osteoporosis drugs to depressed patients and antidepressant drugs to osteoporosis patients? That’s a sweet win-win…provided you’re not one of the patients.

If you ARE one of these patients, I think you’ll be interested in a MedPage Today report, published in 2007, that opened with this sentence: “Selective serotonin reuptake inhibitors (SSRIs) have been linked to decreased bone density in older women and men, two related studies found.”

There. Now doesn’t that make MUCH more sense?

Sources:
“Low Bone Mass in Premenopausal Women With Depression” Archives of Internal Medicine, Vol. 167, No. 21, 11/26/07, archinte.ama-assn.org
“Depression Linked to Bone Loss in Premenopausal Women” Ivanhoe Newswire, 11/28/07, ivanhoe.com
“Depression Linked to Bone-Thinning in Premenopausal Women” ScienceDaily, 11/27/07, sciencedaily.com
“Depression Linked to Bone Loss in Younger Women” Amanda Gardner, HealthDay News, 11/26/07, health.usnews.com
“Depression in Premenopausal Women Linked to Low Bone Mass” Judith Groch, MedPage Today, 11/26/07, medpagetoday.com
SSRIs Chase Depression But Bones May Pay Price” Judith Groch, MedPage Today, 6/27/07, medpagetoday.com