Research concludes many not helped by antidepressants

A study conducted by UConn psychology researchers and others has found that several commonly prescribed antidepressants provide little benefit for most people with depression.

The study was published Feb. 26 in the online journal PLoS Medicine.

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 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.

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. He retired in 2003.

The study relied on meta-analysis, which pools data from independent studies.

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 studies of very highly depressed patients.

For studies involving people with less severe depression, the advantage of taking the drug was modest, and did not approach clinical significance, says Johnson.

Indeed, many people in the trials still exhibited high levels of depression even after taking the drugs.

One strength of the investigation was its use of complete data sets, including results that the drugs’ manufacturers did not publish.

The clinical trials analyzed involved four selective serotonin reuptake inhibitors (SSRIs): the drugs fluoxetine (Prozac), venlafaxine (Effexor), nefrazodone (Serzone), and paroxetine (Paxil), which have been widely prescribed in the U.S.

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.

Two drugs that were originally included in the study – citalopram (Celexa) and sertraline (Zoloft) – were ultimately excluded because the researchers were not able to obtain complete data sets.

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.