Q & A: Antidepressants and Bone Health for Anorexia Nervosa Patients

Q: One of my chronically depressed patients with anorexia nervosa (AN) has been reluctant to take antidepressant medications, saying that she’s heard that these medications might cause osteopenia or osteoporosis.  Is there any basis for that concern? (RS, Phoenix)

A: Your patient raises an interesting question about a somewhat controversial issue. In fact, a recent small retrospective study involving 31 pairs of eating disorder patients, about 80.6% of whom were initially diagnosed with AN, suggested that the women with eating disorders who were exposed to selective serotonin reuptake inhibitors (SSRIs) had lower bone mineral density scores on dual x-ray absorptiometry (DEXA) scans than did a comparison group matched for age and diagnosis. Although the eating disorder patients who weren’t taking SSRIs also had below-average DEXA scores, these scores were even lower in the group taking SSRIs. The SSRI group’s mean scores were in the borderline osteopenia range but were considerably healthier than scores indicating osteoporosis (Eating Disorders: The Journal of Treatment & Prevention. 2013; 21:3, 238-248).

Other researchers have also suggested associations between SSRIs and lower bone mineral densities. However, it’s more complicated than that; the devil may lie in details that haven’t been adequately taken into account in these studies. For example, we know that the risk of bone loss is increased among women with longer periods of amenorrhea and other hormonal variability, deeper and more prolonged periods of depression, and/or borderline personality disorder, and in women who smoke cigarettes. Further, in these patients hormonal variability related to weight loss and other factors is considerable.

Although the intermediate mechanisms aren’t entirely clear, women who are more distressed, e.g., those with abysmal, more serious and extensive depressive episodes and/or borderline personality disorder, are likely to have higher cortisol levels, which are also correlated with greater risk of bone loss. So, it’s conceivable that the women who’ve taken SSRIs actually constitute an especially highly distressed group in the first place. For these women, the fact that they’ve taken SSRIs might primarily serve to indicate the presence of these other underlying states that endanger bone health.

Clearly, additional clinical and laboratory research is necessary before we can ascertain whether SSRIs per se are the culprit. For the time being, in my own practice I still prescribe SSRIs to patients with eating disorders for whom they are clinically indicated.

— J.Y.