Abstract
Introduction: Experimental animal studies provided evidence for a synergistic effect of immunological and psychological stressors on subsequent sickness behaviours. Up to now, little corroborating evidence for such synergy exists for humans, in whom it may provide a mechanism leading to the expression of functional somatic symptoms. The aim of the present study was to determine an interaction between stress(-vulnerability) and an immunological activation on experimental pain sensitivity, i.e., pressure pain threshold and tolerance in healthy humans. Methods: In healthy female participants (n = 25, mean age 22.3 years), negative affectivity (NA) and experienced stress were assessed by questionnaire before receiving a Salmonella typhi vaccine or saline control in a randomized blinded cross-over design. Pressure pain threshold was assessed at the lower back and calves and pain tolerance was assessed at the thumbnail, before and six hours after each injection. Results: Vaccination induced leukocytosis (+100%) and increased serum IL-6 (+670%). NA predicted decreased pain tolerance after vaccination (β = −.57, p = .007), but not after placebo (β = .25, p = .26). Post-hoc analyses also demonstrated an association with administration order. Discussion: NA moderated the effects of inflammation on pain tolerance. This finding is consistent with a synergistic model whereby inflammation may lower the threshold for pain reporting in individuals with increased vulnerability for somatic symptom reporting.
Original language | English |
---|---|
Pages (from-to) | 32-36 |
Journal | Brain, Behaviour, and Immunity |
Volume | 44 |
Early online date | 14 Oct 2014 |
DOIs | |
Publication status | Published - 1 Feb 2015 |
Keywords
- Inflammation
- Inflammatory response
- Interleukin-6
- Cytokines
- Pain sensitivity
- Algometry
- Pain tolerance
- Pain threshold
- Pressure pain
- Experimental pain
- Vaccine
- Placebo
- Randomized control
- Stress
- Life events
- Negative affectivity
- Negative affect
- Human