title: Impaired Pain Modulation in Fibromyalgia Patients in Response to Social Distress Manipulation.
abstract: Fibromyalgia (FM), a chronic pain condition, is associated with abnormalities in pain modulation. A growing body of evidence has shown that social distress modulates pain sensitivity. The current study aimed to assess the effects of social distress manipulation on pain in FM patients compared with positive (rheumatoid arthritis, RA) and negative (pain-free) controls.
  
  
  
  FM, RA patients and pain-free controls (PFC) were recruited. Demographic, medical, and psychological data were collected. Each participant was exposed to 3 study conditions in a random order: the inclusion (positive social effects) and exclusion (negative social effects) conditions of Cyberball, a game that manipulates social distress, and a control condition. Pain sensitivity in response to nociceptive electrical and thermal (cold) stimuli was assessed before and during each study condition.
  
  
  
  In response to electrical stimuli, pain decreased in both the inclusion and exclusion conditions in PFC and RA groups, whereas inclusion conditions significantly increased pain in the FM group. Social manipulation (inclusion or exclusion) did not affect pain sensitivity as measured in response to thermal stimulation.
  
  
  
  These results are in line with previous studies demonstrating altered pain inhibition in FM patients, and suggest that unlike PFC or other non-"stress-related" chronic pain conditions, being socially included may increase pain perception in FM patients. Possible underlying mechanisms and clinical relevance are discussed.
authors.affiliation: *Faculty of Medicine ‡Faculty of Psychology, University of Lisbon †Health Science Institute, Portuguese Catholic University, Portuguesa §Rheumatology Department, CEDOC, NOVA Medical School, Faculty of Medical Sciences, NOVA University of Lisbon, CHLO, Hospital Egas Moniz, Lisboa, Protugal ∥Faculty of Social Welfare and Health Sciences, University of Haifa, Haifa, Israel.
authors.forename: Rita
authors.initials: R
authors.lastname: Canaipa
authors.forename: Alexandre
authors.initials: A
authors.lastname: Castro-Caldas
authors.forename: João Manuel
authors.initials: JM
authors.lastname: Moreira
authors.forename: Fernando
authors.initials: F
authors.lastname: Pimentel-Santos
authors.forename: Jaime Cunha
authors.initials: JC
authors.lastname: Branco
authors.forename: Roi
authors.initials: R
authors.lastname: Treister
mesh_terms: D000328:Adult; D000368:Aged; D001172:Arthritis, Rheumatoid / Q000150:complications; D059350:Chronic Pain / Q000209:etiology* / Q000523:psychology* / Q000628:therapy; D004558:Electric Stimulation / Q000009:adverse effects; D005260:Female; D005356:Fibromyalgia / Q000150:complications*; D006801:Humans; D008875:Middle Aged; D059408:Pain Management; D010147:Pain Measurement; D017288:Pain Threshold / Q000523:psychology; D021641:Recognition, Psychology; D012720:Severity of Illness Index; D012919:Social Behavior; D018709:Statistics, Nonparametric; D013315:Stress, Psychological / Q000209:etiology* / Q000534:rehabilitation*; D011795:Surveys and Questionnaires