NEW ORLEANS, Nov. 22 -- Research has challenged the conventional wisdom that depressed patients need three to four weeks to respond to antidepressant medication and that any earlier response is due to the placebo effect, said an investigator here.
Measurable non-placebo responses may occur during the first week of treatment, studies published last year suggest, said Ronald W. Pies, M.D., of the Tufts New England Medical Center in Boston, at the U.S. Psychiatric & Mental Health Congress here.
Previous studies, some published in the 1980s, found that while a placebo response was evident at week one and continued unabated, a true drug response did not appear until at least week three. Almost no drug-placebo separation occurred before three weeks, Dr. Pies said.
However, more-recent research has uncovered a different pattern. One meta-analysis published last year included 47 double-blind trials of antidepressants. The trials included more than 5,000 patients on active drug and more than 3,000 patients on placebo. Drugs used included selective-serotonin reuptake inhibitors (SSRIs), tricyclics, and heterocyclics, Dr. Pies said.