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Monday, February 27, 2012

More than one way to create a placebo

Placebos are fascinating.  For totally inert substances, they have a remarkable ability to alter how we perceive pain.  One hypothesis for how this might work is that the placebo distracts us from our pain.  To test whether this is true, Jason Buhle, Bradford Stevens and Jonathan Friedman from Columbia University and Tor Wager from the University of Colorado compared traditional placebos with mental distractions.  Not only did both methods ease pain, but the results were cumulative, indicating that two different pain-alleviation processes were involved. 

The researchers put 33 volunteers through a rather harrowing set of experiments. On day one, each person performed calibration tests to determine their pain tolerance levels (when exposed to high temperature) and their performance on memory tests.  Over the next two days, the participants performed similar tasks.  Prior to the application of heat, the effected area was covered with a cream that half the participants (placebo) were told was an analgesic.  In reality, no volunteers received any type of medical pain relief.
The subjects were then further divided such that there were four test protocols.  One quarter received what they thought was an analgesic and were asked to do nothing while their arm was subjected to heat, one quarter received the pretend analgesic and were asked to perform memory tests.  The other half of participants knew they were not getting any pain relief in the cream (controls) and were also divided into those performing memory tasks and those doing nothing.

Both groups (placebo and control) reported less pain during the memory distraction tests. Also, the placebo alone outperformed the control.  Thus, either distraction or placebo lowered perceived pain levels.  Interestingly, the greatest benefit was seen in the group that got both the placebo and the distraction.  In fact, the effect was almost completely additive.

Taken together, these results indicate that mental distraction is itself a worthy placebo, but one that functions independently of medical placebos.  Next time you have a painful procedure planned, don’t forget to bring your sudoku along.  

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