Negative Emotional Influences on Pressure Pain Thresholds: Findings from a Quasi-Randomized Controlled Trial

Objective: Human emotions could affect pain perception, but knowledge from well-powered experiments about how different emotions affect pressure pain thresholds (PPTs) in pain-free individuals are missing. The aim of this quasi-randomized control trial was to investigate the effect of different emotional states on PPTs in four different body locations (upper, right m. trapezius; upper, left m. trapezius; right m. tibialis anterior; left m. tibialis anterior). Methods: Pain-free participants (n = 152) were assigned to four different emotional states (negative n = 38; positive n = 38; distraction control n = 38; control n = 38). Baseline PPTs in each group were measured after a neutral video clip following emotional state induction with video clips (negative; positive; distraction control; control). PPTs were again measured after emotion induction. Results: The main finding was that negative emotion induction significantly lowered PPTs in the m. trapezius and m. tibialis anterior on the left side of the body after correction for multiple comparisons. PPTs were also significantly lower in the left m. tibialis anterior in the distraction control group. No other significant differences in PPT levels were found. Conclusion: Negative emotions, but not positive emotions, could significantly lower PPTs in the left m. trapezius and the left m. tibialis anterior in healthy individuals. A practical implication may be that negative emotions might negatively affect pain states through descending pain modulation.