Antidepressant medications appear to help only very severely depressed people and the drugs work no better than placebos in many patients, British researchers said Tuesday.
Their findings raise questions about the use of antidepressants, the most commonly prescribed drugs in the U.S. The study, led by Irving Kirsch of the University of Hull, concludes that less severely depressed patients might benefit just as much from therapy, exercise or other non-medical interventions.
"There is little reason to prescribe new-generation antidepressant medications to any but the most severely depressed patients unless alternative treatments have been ineffective," wrote researchers in the latest issue of the public Library of Science Medicine.
Researchers reviewed published and unpublished U.S. Food and Drug Administration studies of the four of the most commonly prescribed new generation antidepressants to learn whether patients' response depended on how depressed they were to begin with.
The studied drugs included Prozac, Effexor, Paxil and Serzone, which are all so-called selective serotonin reuptake inhibitors, or SSRIs. About 118 million antidepressant prescriptions were issued in 2005 in the U.S., according to the National Center for Health Statistics.
The researchers found that compared with placebo, the antidepressant medications did not yield clinically significant improvements in depression in patients who initially had moderate or even very severe depression. The study found that significant benefits occurred only in the most severely depressed patients.
"Although patients get better when they take antidepressants, they also get better when they take a placebo, and the difference in improvement is not very great. This means that depressed people can improve without chemical treatments," Kirsch said in a statement.
Placebo effect common in depression
The study provides valuable insight to researchers, patients and, most important, primary care doctors who prescribe most of the antidepressants, said David Barlow, founder and director emeritus for the Center for Anxiety and Related Disorders at Boston University.
"The take-home message is there are probably too many people on medications who might not need to be on these medications," Barlow said.
Patients taking the drugs should not stop without consulting a doctor, Barlow cautioned, but they might consider non-medical therapies before beginning or continuing the medication.
Mary Ann Rhyne, a spokeswoman for Paxil maker GlaxoSmithKline, said the study only looked at data submitted prior to the drug's U.S. approval.
"The authors have failed to acknowledge the very positive benefit these treatments have provided to patients and their families who are dealing with depression and they are at odds with what has been seen in actual clinical practice," Rhyne said.
"This analysis has only examined a small subset of the total data available, while regulatory bodies around the world have conducted extensive reviews and evaluations of all of the data available," she said.
JoNel Aleccia and Reuters contributed to this report.