New research shows that while many antidepressants help most people who take them, a small group of people who take them will actually feel more depressed than if they had just been taking a placebo or sugar pill.

The antidepressants studied included selective serotonin reuptake inhibitors (SSRIs) and Cymbalta (duloxetine).

The new study from Yale University researchers re-examined data from seven existing studies and 2,515 participants. In these previous studies, patients received the antidepressant drug Cymbalta (duloxetine), another SSRI antidepressant, or a placebo pill for two months.

The researchers found that most people getting the placebo treatment (a sugar pill) tended to report small, gradual improvements in depression symptoms. Depression symptoms were measured using a standardized depression assessment called the Hamilton Scale for Depression (HAM-D), which is administered by a professional.

However, most people receiving an antidepressant drug like Cymbalta and who responded to such treatment felt a greater relief in their depression symptoms faster than those taking a placebo. The researchers found that regardless of treatment (antidepressant drug or placebo), 76.3 percent of all the patients in the sample responded positively to treatment.

But a third group of patients examined — 23.7 percent of patients — did not respond to treatment (regardless of whether it was an antidepressant or placebo).

And when researchers examined the depression severity scores of the non-responder’s who were taking an antidepressant, they found these patients actually got worse while taking an antidepressant.

The final results suggest that up to a fifth of patients who are taking an antidepressant may initially feel worse.

The authors conclude, “Most patients treated with serotonergic antidepressants showed a clinical trajectory over time that is superior to that of placebo-treated patients.

“However, some patients receiving these medications did more poorly than patients receiving placebo.

“These data highlight the importance of ongoing monitoring of medication risks and benefits during serotonergic antidepressant treatment. They should further stimulate the search for biomarkers or other predictors of responder status in guiding antidepressant treatment.”

Differences between antidepressant responders and non-responders were seen as early as a week or two into treatment. Initial improvements in treatment, according to the researchers, seem to predict who will have a better outcome on any antidepressant.

Two of the study’s three authors are affiliated with Eli Lilly, the maker of Cymbalta.

The new study appears in the journal Archives of General Psychiatry.

Source: Archives of General Psychiatry