Insights gleaned from brain imaging technologies that allow scientists
to observe neurobiological mechanisms of the placebo effect may one day alter
the way clinical trials are conducted and provide clues to treating pain and
other disorders.
Using magnetic resonance imaging and positron emission tomography scans,
scientists have provided the first direct evidence that the endogenous opioid
system, specifically activity on the opioid receptors, mediates the placebo
effect (Zubieta et al. J Neurosci. 2005;25:7754-7762).
The findings build on other recent imaging studies that have identified brain
areas activated or monitored the activity of single neurons when a placebo
is given.