Different Expectations Affect Pain Perception Differently, New NIH Study Says

How exactly are expectations about pain formed, and how can they influence how we perceive it? A new study by NIH researchers led by Lauren Atlas provides an answer to this question. The article was published in the journal JNeurosci.

What did you study?

The researchers tried to figure out how different types of expectations—based on external cues or what a doctor says—influence how much pain a person feels.

The experiment involved 40 healthy volunteers who were given pain-inducing thermal stimuli during neuroimaging scans. The participants:

• External cues indicating the possible intensity of pain (e.g. visual cues) were presented.
• Sometimes a placebo cream was applied, presented as a pain reliever.

What did the study show?

• External cues reduced pain in all participants, even without "treatment."
• The placebo cream only reduced pain in some participants.
• When the placebo cream was applied along with the cues, the effect of the cues was weakened.
• Different areas of the brain were activated when exposed to different expectations:
  • External cues affected the neurobiomarker of pain.
  • Treatment expectations influenced evaluative brain regions associated with pain perception and interpretation.

Conclusions:

The study found that different types of expectations activate different mechanisms in the brain:

• Expectations based on external cues are more stable and universal.
• Expectations based on treatment information are more individual and unpredictable.

Researcher's comment:

"If a doctor says, 'This is going to hurt,' that's a signal. If they say, 'This treatment will make the pain go away,' that's a different expectation. Our research shows that these two forms of communication have different effects on pain perception,"
says Lauren Atlas, NIH.

Practical significance:

For clinicians, this means that the way patients are told can have a significant impact on their pain experience. The use of external cues or verbal explanations about treatment must be conscious and contextually tailored.

This discovery may be useful in:

• pain medicine;
• psychology of expectation and perception;
• development of clinical approaches to pain relief and communication with patients.

This study highlights the importance of psychological factors in medicine and provides new tools to improve the effectiveness of pain relief without changing the physical impact.