NEW YORK (Reuters Health) - More than a quarter of Americans taking antidepressants have never been diagnosed with any of the conditions the drugs are typically used to treat, according to new research.
That means millions could be exposed to side effects from the medicines without proven health benefits, researchers say.
"We cannot be sure that the risks and side effects of antidepressants are worth the benefit of taking them for people who do not meet criteria for major depression," said Jina Pagura, a psychologist and currently a medical student at the University of Manitoba in Canada, who worked on the study.
"These individuals are likely approaching their physicians with concerns that may be related to depression, and could include symptoms like trouble sleeping, poor mood, difficulties in relationships, etc.," she added in an e-mail to Reuters Health. "Although an antidepressant might help with these issues, the problems may also go away on their own with time, or might be more amenable to counseling or psychotherapy."
The researchers tapped into data from the Collaborative Psychiatric Epidemiologic Surveys, which include a nationally representative sample of more than 20,000 U.S. adults interviewed between 2001 and 2003.
Roughly one in ten people told interviewers they had been taking antidepressants during the past year. Yet a quarter of those people had never been diagnosed with any of the conditions that doctors usually treat with the medication, such as major depression and anxiety disorder.
According to The National Institute of Mental Health, nearly 15 million American adults suffer from major depression, and 40 million more have anxiety disorders.
Although the survey didn't include all mental illnesses that might have led doctors to prescribe an antidepressant -- say, obsessive-compulsive disorder or to help quit smoking -- other experts said the new findings are not exaggerated.
"Reviews of claims records, which are diagnoses actually given by health care professionals, suggest that only about 50% of patients who are prescribed antidepressants receive a psychiatric diagnosis," said Dr. Mark Olfson, a psychiatrist at Columbia University in New York.
"These findings raise questions about the clinical appropriateness of antidepressant treatment selection for many primary care patients," he added in an e-mail to Reuters Health.
With sales of $9.9 billion in 2009, up three percent since the previous year, antidepressants rank fourth among prescription drugs in the U.S., according to IMS Health, a company that analyzes the pharmaceutical industry.
Popular brand names include Pfizer's Zoloft, Forest Laboratories' Lexapro and Eli Lilly's Prozac.
While studies have shown the drugs may help some people with depression, they come with a price tag -- and not only the $100 or more that a month's supply can cost. Some users experience sexual problems or gain weight, for instance.
"Nearly all medication has side effects, so there are undoubtedly a large number of Americans who are taking antidepressants that may not be effective at treating their conditions, yet they suffer from the side effects," said Jeffrey S. Harman, an expert in health services at the University of Florida in Gainesville, who was not involved in the new study.
"Not to mention inappropriate use of our health care dollars that comes along with inappropriate prescribing," he added in an e-mail.
Still, Harman said the findings, published in the Journal of Clinical Psychiatry, didn't necessarily mean doctors are prescribing more antidepressants than they should.
"As far as overprescribing, I don't think you can say that it is occurring as a blanket statement," he explained. "There are undoubtedly many people being prescribed antidepressants that may not be effective for them, but there are also millions of Americans suffering from depression who are not being prescribed antidepressants or are being prescribed them at a suboptimal dose."
Pfizer did not comment directly on the new findings, but told Reuters Health it was dedicated to ensuring "that patients and their doctors have the most up to date medical information on which to base their treatment decisions."
SOURCE: bit.ly/eXPVSL Journal of Clinical Psychiatry, online January 25, 2011.