More than a quarter of people in the US who take antidepressants have never been diagnosed with any of the conditions the drugs are typically used to treat, according to a study.
As a result, millions could be exposed to side effects from the medicines without proven health benefits, said Jina Pagura, a psychologist and currently a medical student at the University of Manitoba in Canada, and colleagues who worked on the study.
"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," Pagura said in an e-mail.
For the study, published in the Journal of Clinical Psychology, Pagura and colleagues tapped into data from the Collaborative Psychiatric Epidemiologic Surveys, which include a nationally representative sample of more than 20,000 US adults interviewed between 2001 and 2003.
Roughly one in ten people told interviewers they had been taking antidepressants during the previous year, yet a quarter of those people had never been diagnosed with any of the conditions that doctors usually treat with the medications, such as major depression and anxiety disorder.
"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," Pagura said.
"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 counselling or psychotherapy."
According to the National Institute of Mental Health, nearly 15 million people in the US have 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, other experts said the latest 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 Mark Olfson, a psychiatrist at Columbia University in New York.
With sales of $9.9bn in 2009, up 3% from the previous year, antidepressants rank fourth among prescription drugs in the US, said IMS Health, a company that analyses the pharmaceutical industry.
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.
But it is still not easy to say if antidepressants are being overprescribed as a blanket statement, health experts said.
"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," said Jeffrey Harman, in health services at the University of Florida in Gainesville, who was not involved in the study. - (Reuters, February 2011)