Anti-Depressants!

[Amskeptic]

Read up! (it's a little dense) Respectful discussion welcome!

The response to placebo in these trials was exceptionally large, duplicating more than 80% of the improvement observed in the drug groups. In contrast, the effect of placebo on pain is estimated to be about 50% of the response to pain medication [24–26]. A substantial response to placebo was seen in moderately depressed groups and in groups with very severe levels of depression. It decreased somewhat, but was still substantial, in groups with the most-severe levels of depression.

http://www.plosmedicine.org/article/inf ... ed.0050045