[cpncrunch]

The results from ketamine are very impressive, however there is still the possibility that it is due to the placebo effect:

"Consistent with all of the published randomized, placebo-controlled studies with ketamine, we also found short-lived perceptual disturbances26,49,50; such symptoms could have affected study blind. Hence, limitations in preserving study blind may have biased patient reporting by diminishing placebo effects, thereby potentially confounding results. One potential study design in future studies with ketamine might be to include an active comparator such as intravenous amphetamine (a dopamine agonist), which also produces psychotogenic effects."

http://archpsyc.jamanetwork.com/article.aspx?articleid=66819...