From mouse to man - Social Anxiety Disorder and The Placebo Effect

In a study conducted in 2008, social anxiety disorder sufferers were asked to engage in a stressful public speaking event. They were then "treated" for 8 weeks (with placebo) and then again asked to speak in public. 40% of the placebo-treated patients showed an improvement in their symptoms over the 8 week period.

A Link between Serotonin-Related Gene Polymorphisms, Amygdala Activity, and Placebo-Induced Relief from Social Anxiety. The Journal of Neuroscience, 2008

Dummy drugs 'can relieve anxiety'

Simply taking a tablet may make people feel better - scientists say they have found that the "placebo effect" of dummy drugs can relieve anxiety as well as pain. 

Swedish volunteers were shown a series of unpleasant pictures and then given an anti-anxiety drug. The test was later repeated, but with a fake drug. "The placebo changes what we expect. When we expect that something unpleasant should become less unpleasant, it really does" Dr Petrovic

The effects on calming the people's nerves were similar, the scientists told the journal 

Neuron. - BBC online news article