The expectation of receiving pain can lead to feeling pain, according to a new brain imaging study from the University of Colorado Boulder.
Researchers used a functional MRI machine to examine how people's brains responded to pain. The 34 participants were shown a low heat or high, painful heat symbol. Then some degree of painful but non-damaging heat stimulus was applied to their forearm or leg.
When subjects saw the painful heat symbol before receiving the stimulus, brain regions associated with pain lit up more. They also reported feeling more pain whether the stimulus was hot or not.
The study found that the subjects showed "confirmation bias." If they expected pain and got it, they expected the pain again. Conversely, if participants expected pain and didn't get it, they failed to learn from the experience.
"Negative expectations and fear of pain can help create a cycle where those expectations contribute to worse pain, and worse pain contributes to more negative expectations," said psychology and neuroscience professor Tor Wager, senior author of the paper published this month in Nature Human Behaviour.
The study results might lead to more effective treatments for people who suffer from chronic pain by creating support for psychological intervention that can help break this cycle, Wager said.
"If you have a cycle, where pain signaling coming from your body is amplified and enhanced depending on the negative expectations that you have and the fear you have," he said. "Then reducing the fear can actually decrease sensitization in those pain circuits over time."