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On depression, placebo proves helpful
Participants reported St. John's wort was less so.
Experts say simply getting help makes a difference.


Inquirer Staff Writer

 

For treating moderately severe depression, a sugar pill worked better than a popular herbal supplement and rivaled the prescription antidepressant Zoloft on most measures of effectiveness, according to a new study.

The research, led by Duke University Medical Center physicians, cannot rule out the possibility that the herbal supplement, St. John's wort, relieves milder depression. But the findings suggest that people with serious symptoms should consult a therapist rather than simply self-medicate with the herb.

"I don't recommend self-medicating with anything if you are suffering from a major depression," said Duke University psychiatrist Jonathan R. Davidson, an author of the study in today's Journal of the American Medical Association.

The study also illustrates a well-known problem with studies of treatments for depression: the placebo effect is a powerful factor that must be taken into account.

"When people who are depressed get help, they feel more hopeful, and that alone can lead to improvement," Davidson said.

Indeed, in another article in the journal, Columbia University researchers analyzed clinical trials of antidepressants over the last 20 years and found that patients' response to placebo has been increasing. This may mean that less severely depressed patients are volunteering for studies, or that they enter studies with a greater awareness that depression is treatable, Columbia psychiatrist Timothy Walsh said.

"It is crucial to have a placebo group," Walsh said. "If they [Duke researchers] hadn't had a placebo group, they might have reached a very different conclusion. We'd be hearing that St. John's wort is as good as Zoloft."

In the study, 340 patients from 12 psychiatric clinics across the country were randomly assigned to take placebo, St. John's wort (the plant hypericum), or Zoloft (known chemically as sertraline) for eight weeks.

Overall, 32 percent of the placebo group ended up with better scores on key tests of depression severity, compared with 24 percent of patients taking St. John's wort and 25 percent taking Zoloft. The tests measured depressive symptoms such as insomnia, anxiety and loss of appetite.

Although Zoloft fell short on this overall measure, it was more effective than placebo or St. John's wort on a scale that measured patients' clinical improvement. In addition, 23 percent of patients on Zoloft showed a partial response, compared with only 14 percent on the herb and 11 percent on placebo.

The researchers speculate that the Zoloft doses and duration may have been too limited to show maximum effect. None of the patients took more than 100 mg, which is half of the highest dose recommended by Pfizer, the manufacturer.

Zoloft caused the most adverse effects, with 40 percent of patients experiencing temporary diarrhea and nausea. The desire to avoid side effects is a big reason many people turn to herbal supplements.

But St. John's wort is not free of such problems.

"Several studies have shown that St. John's wort interacts dangerously with several medications such as those used to treat HIV/AIDS, certain cardiac conditions, and even those that keep the body from rejecting organs after transplant," said Robert Califf, director of the Duke Clinical Research Institute.

A study presented this week at a San Francisco cancer conference also found the herb may reduce the effectiveness of irinotecan, a commonly used cancer drug.


Contact Marie McCullough

at 215-854-2720 or mmccullough@phillynews.com.