When it comes to the risk of weight gain, antidepressants are not created equal.
A study published Wednesday in JAMA Psychiatry suggests that patients taking citalopram (Celexa) are more likely to pack on pounds than those on antidepressants such as bupropion (Wellbutrin) and nortriptyline (Aventyl).
For the study, funded by the U.S. National Institute of Mental Health, researchers analyzed changes in body weight in 22,610 adults prescribed 11 different antidepressants by physicians in an integrated health-care system in Boston.
A year after starting antidepressant medication, patients taking Celexa had a mean increase in body mass index (BMI) of almost half a per cent, compared to virtually nil for patients on Wellbutrin. For a 5-foot-10 man who weighs 175 pounds, that translates to a weight gain after 12 months of Celexa of about two pounds.
Although the magnitude of weight-gain risk between antidepressants "is relatively small," the study authors wrote, "these differences may lead clinicians to prefer certain treatments according to patient preference or in individuals for whom weight gain is a particular concern."
Dr. Rohan Ganguli, a psychiatrist conducting weight-management research at Toronto's Centre for Addiction and Mental Health, said the risk of weight gain associated with Celexa is well known in psychiatry, while Wellbutrin is prescribed not only as an antidepressant but also as a weight-loss drug.
"As a clinician, this comes as no surprise," he said.
But he added that the study is useful for clinicians because it is based on a year's worth of data from a large number of patients in a high-quality health-care system.
Unlike research studies involving carefully selected patients or volunteers, "this is from the real world," Ganguli said.
He noted that Wellbutrin is not normally a first choice for treating depression – despite its potential to prevent weight gain – since it carries the risk of intensifying anxiety and interfering with sleep. "It's an activating drug," he said, whereas Celexa is a common choice because "it's cheap, and it works."
He pointed out that a patient could gain weight on any antidepressant, including Wellbutrin, since people have individual responses to different drugs: "You don't find out until you try it."
Nevertheless, Ganguli said he will discuss the results of the JAMA study with patients who are concerned about gaining weight, since weight gain affects well-being and is a common reason patients go off antidepressants.
"They certainly bring it up," he said.
An earlier version of this article misinterpreted the terms mean and median. This version has been edited to reflect the correct data from the study mentioned.