title: Acute stress contributes to individual differences in pain and pain-related brain activity in healthy and chronic pain patients.
abstract: Individual differences in pain sensitivity and reactivity are well recognized but the underlying mechanisms are likely to be diverse. The phenomenon of stress-induced analgesia is well documented in animal research and individual variability in the stress response in humans may produce corresponding changes in pain. We assessed the magnitude of the acute stress response of 16 chronic back pain (CBP) patients and 18 healthy individuals exposed to noxious thermal stimulations administered in a functional magnetic resonance imaging experiment and tested its possible contribution to individual differences in pain perception. The temperature of the noxious stimulations was determined individually to control for differences in pain sensitivity. The two groups showed similar significant increases in reactive cortisol across the scanning session when compared with their basal levels collected over 7 consecutive days, suggesting normal hypothalamic-pituitary-adrenal axis reactivity to painful stressors in CBP patients. Critically, after controlling for any effect of group and stimulus temperature, individuals with stronger cortisol responses reported less pain unpleasantness and showed reduced blood oxygenation level-dependent activation in nucleus accumbens at the stimulus onset and in the anterior mid-cingulate cortex (aMCC), the primary somatosensory cortex, and the posterior insula. Mediation analyses indicated that pain-related activity in the aMCC mediated the relationship between the reactive cortisol response and the pain unpleasantness. Psychophysiological interaction analysis further revealed that higher stress reactivity was associated with reduced functional connectivity between the aMCC and the brainstem. These findings suggest that acute stress modulates pain in humans and contributes to individual variability in pain affect and pain-related brain activity.
authors.affiliation: Département de Psychologie, Université de Montréal, Montreal, Quebec, Canada H3C 3J7. etienne.vachon-presseau@umontreal.ca
authors.forename: Etienne
authors.initials: E
authors.lastname: Vachon-Presseau
authors.forename: Marc-Oliver
authors.initials: MO
authors.lastname: Martel
authors.forename: Mathieu
authors.initials: M
authors.lastname: Roy
authors.forename: Etienne
authors.initials: E
authors.lastname: Caron
authors.forename: Geneviève
authors.initials: G
authors.lastname: Albouy
authors.forename: Marie-France
authors.initials: MF
authors.lastname: Marin
authors.forename: Isabelle
authors.initials: I
authors.lastname: Plante
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Sullivan
authors.forename: Sonia J
authors.initials: SJ
authors.lastname: Lupien
authors.forename: Pierre
authors.initials: P
authors.lastname: Rainville
mesh_terms: D000328:Adult; D001921:Brain / Q000098:blood supply / Q000503:physiopathology*; D001931:Brain Mapping; D059350:Chronic Pain / Q000473:pathology* / Q000503:physiopathology*; D005260:Female; D006801:Humans; D006854:Hydrocortisone / Q000378:metabolism; D007091:Image Processing, Computer-Assisted; D007206:Individuality; D016014:Linear Models; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood; D058748:Pain Perception / Q000502:physiology; D017288:Pain Threshold / Q000502:physiology; D011569:Psychiatric Status Rating Scales; D011601:Psychophysics; D012463:Saliva / Q000378:metabolism; D013315:Stress, Psychological / Q000503:physiopathology*; D055815:Young Adult
chemical_list: D010100:Oxygen; D006854:Hydrocortisone