University of Connecticut |
Psychologists analyze antidepressants
Two UConn psychology researchers are co-authors of a major new study of the effect of commonly prescribed antidepressants. The analysis of the data from trials of four popular new-generation antidepressant drugs was conducted by two researchers from UConn’s Center for Health, Intervention, and Prevention (CHIP): post-doctoral researcher Tania Huedo-Medina, and Blair Johnson, a professor of social psychology in CLAS. The study was led by Irving Kirsch, a psychology professor at Britain’s University of Hull, who is a professor emeritus of clinical psychology at UConn who retired in 2003. It found that placebos on average were about 80 percent as effective as four highly prescribed antidepressant drugs. The study was published Feb. 26 in the online journal PLoS Medicine and has been reported on widely in the popular media. It analyzed a large amount of data from 35 complete clinical trials submitted to the federal Food and Drug Administration (FDA) from 1987 to 1999. The dataset, which included study results not before made public, was obtained from the FDA through a Freedom of Information Act request. The study relied on meta-analysis, which pools data from independent studies. Johnson and Huedo-Medina conducted the meta-analysis. Before antidepressants – the most commonly prescribed class of drugs in the United States in 2006 – are approved for licensing by the FDA, they must undergo clinical trials. These compare their ability to alleviate depression with the effects patients experience when taking a placebo. Neither the patients nor the researchers in the original studies knew who was receiving the drug and who the placebo. Clinically significant improvement appeared only in trials of very highly depressed patients. For trials involving people with less severe depression, the advantage of taking the drug was modest, and did not approach clinical significance, says Johnson. The study used complete data sets, including results that the drugs’ manufacturers did not publish. The trials lasted from four to eight weeks and included 5,133 adult patients, of whom 3,292 were randomly chosen for medication and 1,841 received placebos. The study showed that those who took the antidepressants did get a bit better. But those who took the dummy pills also got better – a phenomenon known as the placebo effect. The placebo effect in the trials was exceptionally large, the authors found. On average, it was about 80 percent as large as the impact of the drugs. For comparison, in trials of pain medication, the average placebo effect is about 50 percent as large as the effect of taking the genuine drug. “We find that the overall effect of new-generation antidepressant medications is below recommended criteria for clinical significance,” the paper states. “Given the large placebo effect we observed in our study, it would make sense for clinicians to exhaust other treatment options for depression before prescribing medication for all but the most severely depressed patients,” Johnson says. “Taking any medication, whether a real drug or not, provides a trigger for improvement, an expectancy of improvement,” he adds. Kirsch’s previous research, much of it conducted at UConn, already had cast doubt on the effectiveness of new-generation antidepressants. Kirsch tapped his former colleague Johnson, who specializes in studying social influence, to participate in his latest study because of his expertise in meta-analysis. Johnson has published 25 such studies in his 20-year career and has numerous publications centering on the methods involved in meta-analysis, including software. His Synthesis of HIV/AIDS Research Project, funded with $3 million in grants from the National Institutes of Health over the past decade, has directly supported 10 meta-analyses in the areas of HIV prevention, HIV risk behavior, and HIV medication adherence. Huedo-Medina, who works with Johnson, is a post-doctoral researcher who focuses on quantitative methods, especially meta-analysis. She already has participated in four large-scale research synthesis projects. The psychology department at UConn was recently ranked fifth in the nation in a National Science Foundation listing of the top institutions for psychology research, both in federal research expenditures and total research expenditures for 2006. For a video clip of Blair Johnson discussing the study with New Zealand’s Channel 3, go to http://www.tv3.co.nz/News/HealthNews/Story/tabid/420/articleID/47535/cat/84/Default.aspx For the paper in the Feb. 26 issue of PLoS, go to http://medicine.plosjournals.org/perlserv/?request=get-document&doi=10.1371/journal.pmed.0050045
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