Psilocybin for depression

An experiment found that psilocybin cured depression in around 1/3 of the test subjects.

I am surprised that the study did not include the clearest form of control group — some patients whose treatment did not actually include any psilocybin. The contrast in results between 25mg of psilocybin and 1mg may have demonstrated that the benefits are real, but a placebo control would have given more certainty.