By Ronnie Cohen

NEW YORK (Reuters Health) - People who take antidepressants tend to put on a few pounds, a new study confirms, and some of the drugs are linked to more weight gain than others.

Using health records from one New England healthcare system, researchers studied 19,244 adults treated with antidepressants, recording their weights over the course of a year.

The results showed that people taking citalopram (Celexa), from a class of antidepressants known as selective serotonin reuptake inhibitors, or SSRIs, gained more than two and a half pounds, on average.

Other SSRIs were associated with weight gain similar to citalopram, with people taking fluoxetine (Prozac) gaining on average a pound and a half and those taking sertraline (Zoloft) gaining nearly two pounds, the authors write in JAMA Psychiatry.

On the other hand, people taking bupropion (Wellbutrin) lost on average nearly half a pound. The tricyclic antidepressants nortriptyline and amitriptyline were also linked with significantly less weight gain than the SSRIs.

“Our study provides more support for the idea that if weight is a major concern, Wellbutrin is a good option,” senior author Dr. Roy Perlis told Reuters Health. Perlis is a psychiatrist at Harvard Medical School and director of the Center for Experimental Drugs and Diagnostics at Massachusetts General Hospital in Boston.

“There’s no question we see less weight gain with Wellbutrin,” he said. “But in absolute terms, the difference is rather small.”

On average, people taking antidepressants “will gain a very modest amount of weight . . . between half a pound and perhaps two pounds if they stayed on the medicine for about a year,” he said. But some people will gain much more, he said.

About one in 10 Americans takes antidepressants, according to the Centers for Disease Control and Prevention (CDC). Use of the drugs rose 400 percent over the past two decades, making them the most frequent prescription for Americans ages 18 to 44.

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At the same time, the obesity rate has swelled, with more than one-third of U.S. adults now considered obese.

“We in practice have long since watched the effect of antidepressants on weight,” Dr. Anne Peters told Reuters Health. “The key to this medicine is don’t overmedicate; don’t use drugs unless there’s a good reason.”

Peters directs the University of Southern California Clinical Diabetes Program in Beverly Hills and was not involved in the current study.

In addition to depression, a substantial percentage of study participants were prescribed antidepressants for anxiety or pain or as an aid to quit smoking. People who take antidepressants for reasons other than depression and are prone to weight gain may want to consider alternatives, Peters said.

“We’ve got to individualize this and not keep people on antidepressants forever,” she said. “People shouldn’t stay on these drugs if they’re contributing to their weight gain and they’re no longer needed.”

On the other hand, she said, “Nobody wants to gain weight, but I sure don’t want to see people depressed.”

More than 60 percent of Americans taking antidepressants have been on them for two years or longer, and 14 percent have taken the drugs for 10 years or more, according to the CDC.

Peters noted that Wellbutrin can agitate anxious people and therefore may be a poor match for some people with depression.

Wellbutrin affects different brain chemicals than do SSRIs, and some of those chemicals may play a role in appetite. Researchers don’t know all the reasons why some antidepressants appear to cause weight gain and others do not, Perlis said.

Some people gain weight and others lose weight as a result of depression. Consequently, researchers have trouble untangling the effects of medication and the effects of depression on weight, Perlis said.

The new study also can’t prove the antidepressants were responsible for weight gain.

“A one-size-fits-all solution isn’t right,” Perlis said. “We desperately need newer, better antidepressants in terms of effectiveness.”

Perlis and one of his co-authors have consulted for and received funding from numerous antidepressant drug manufacturers. But Perlis said all the drugs he studied are now available as generics.

SOURCE: http://bit.ly/1p2CpwS JAMA Psychiatry, online June 4, 2014.