Clinical trials in all areas of medicine turn up some degree of "placebo effect" -- the phenomenon of people who are given a sham treatment, instead of the real thing, getting better anyway. Placebo responses are particularly common in certain disorders, depression being one.
In the new study, researchers re-analyzed findings from a 2002 clinical trial that compared the antidepressant sertraline (Zoloft), the herbal depression treatment St. John's wort and a placebo.
The original study, which included 340 people with moderate depression, had found that neither treatment was any more effective than the placebo when taken for up to six months.
But the current study looked at the data in a different way: It asked whether patients who thought they were getting the real treatment were more likely to improve than those who thought they were on the placebo.
All of the trial patients had been "blinded" as to whether they were receiving the antidepressant, the herb or the placebo. But at the eight-week mark of the study, they were asked to guess which treatment they were taking.
And it turns out that people who thought they were using the antidepressant or St. John's wort were more likely to improve than those who thought they'd been assigned to the placebo group.
Of 71 patients who guessed they were using sertraline, a little more than half were treatment "responders" at week eight -- meaning they'd had at least a 50 percent reduction in their score on a standard measure of depression symptoms.
People who thought they were on St. John's wort fared even better: 68 percent of those 90 patients were treatment responders. And of the ones who correctly guessed that they were on the herb, a full 80 percent responded.
In contrast, only 24 percent of all patients who thought they were on a placebo responded to treatment.
The findings do not prove that beliefs drive people's responses to depression treatment, according to lead researcher Dr. Justin Chen, of Massachusetts General Hospital in Boston.
It's possible that people who felt better at the eight-week mark were more likely to guess that they were on active treatment -- and, specifically, the one they hoped they were getting, Chen pointed out.
But, he said in an interview, the findings add to a large body of evidence that patient beliefs are important in their responses to treatment -- and to depression therapy in particular.
"In this study, patients' beliefs regarding treatment appeared stronger than the actual treatment received," Chen said.
He added, though, that the findings do not mean that antidepressants have no actual biologic effect, or that the effects of depression therapy all depend on a person's mindset.
"I do not think the placebo effect is the whole story," Chen said.
He pointed to some evidence that antidepressants may work better for people with more-severe symptoms, rather than mild to moderate depression.
In a review published last year in the Journal of the American Medical Association, researchers concluded that overall, antidepressants showed a "substantial" benefit over placebos for people with severe depression. But the advantage was minimal to "non-existent" for people with mild to moderate symptoms.
Those findings were based on six clinical trials with a total of 718 patients.
"There is a lot of debate right now about antidepressant efficacy," Chen said.
So where does that leave people seeking help for depression?
Chen said it's important for doctors and patients to be aware that beliefs surrounding treatment matter. If your doctor recommends an antidepressant or other depression therapy, and you have reservations, speak up rather than just accepting a treatment you're not comfortable with, Chen advised.
"You should feel comfortable bringing up your concerns," he said. Feeling positive about your treatment decision may make a difference.
"It's best to be as optimistic as you can be about getting better," Chen said.
More studies are needed to back up the current findings, Chen and his colleagues say. And those should include studies that do not focus on alternative remedies.
The clinical trial Chen's team studied was originally billed as a study of St. John's wort, and it may have attracted a large number of people who were enthusiastic about the herb, or alternative remedies in general.
So the study group may not be reflective of all people who suffer from depression, the researchers say.
Some of Chen's co-researchers on the study have received research funding from drug companies, including antidepressant makers. The study was funded by Massachusetts General Hospital.
SOURCE: http://bit.ly/sX5ZTx Journal of Clinical Psychiatry, online October 4, 2011.
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