A pain in the bud? Implications of cross-modal sensitivity for pain experience

There is growing evidence that enhanced sensitivity to painful clinical procedures and chronic pain are related to greater sensitivity to other sensory inputs, such as bitter taste. We examined cross-modal sensitivities in two studies. Study 1 assessed associations between bitter taste sensitivity, pain tolerance, and fear of pain in 48 healthy young adults. Participants were classified as non-tasters, tasters and super-tasters using a bitter taste test (6-n-propythiouracil; PROP). The latter group had significantly higher fear of pain (Fear of Pain Questionnaire) than tasters (p=.036, effect size r = .48). There was only a trend for an association between bitter taste intensity ratings and intensity of pain at the point of pain tolerance in a cold pressor test (p=.04). In Study 2, 40 healthy young adults completed the Adolescent/Adult Sensory Profile before rating intensity and unpleasantness of innocuous (33 °C), moderate (41 °C), and high intensity (44 °C) thermal pain stimulations. The sensory-sensitivity subscale was positively correlated with both intensity and unpleasantness ratings. Canonical correlation showed that only sensitivity to audition and touch (not taste/smell) were associated with intensity of moderate and high (not innocuous) thermal stimuli. Together these findings suggest that there are cross-modal associations predominantly between sensitivity to exteroceptive inputs (i.e., taste, touch, sound) and the affective dimensions of pain, including noxious heat and intolerable cold pain, in healthy adults. These cross-modal sensitivities may arise due to greater psychological aversion to salient sensations, or from shared neural circuitry for processing disparate sensory modalities.