henry copeland:

Antidepressants and the Placebo Effect

Many patients in clinical trials realize that they have been given the real drug, rather than the placebo, most likely because of the drug’s side effects. What effect is this likely to have in a clinical trial? We do not have to guess at the answer to this question. Bret Rutherford and his colleagues at Columbia University have provided the answer. They examined the response to antidepressants in studies that did not have a placebo group with those in studies where they did have a placebo group (Rutherford, Sneed, & Roose, 2009). The main difference between these studies is that in the first case, the patients were certain they were getting an active antidepressant, where as in the placebo-controlled trials, they knew that they might be given a placebo. Knowing for sure that they were getting an active drug boosted the effectiveness of the drug significantly. This supports the hypothesis that the relatively small difference between drug and placebo in antidepressant trials are at least in part due to “breaking blind” and discerning that one is in the drug group, because of the side effects produced by the drug.
- www.ncbi.nlm.nih.gov