Table 1.

Participant demographics

NAgeSexWeightAnxiety (HADS)Depression (HADS)Disease duration
Healthy volunteers28 (13 saline; 15 naloxone)39.9 ± 12.525 female; 3 male157.1 lb ± 33.94.93 ± 3.111.93 ± 1.73NA
Chronic pain (FM) patients24 (11 saline; 13 naloxone)43.7 ± 13.323 female; 1 male160.3 lb ± 34.48.35 ± 4.554.74 ± 2.9910.3 ± 7.4 years since diagnosis; 11.2 ± 6.8 years since reported symptom onset; mean FIQ score 43.7 ± 19.7
  • Chronic pain patients were included if they had had chronic widespread pain for at least 1 year prior to study participation with an average daily intensity of at least 4 of 10. FM diagnosis was confirmed through medical records. All participants were excluded for smoking (>10 cigarettes per week), excessive alcohol use (>7 drinks/week or 5 drinks in 1 setting), recreational drug use, pregnancy or breastfeeding, major medical or psychiatric conditions (past or present), recent use of opioids, and MRI contraindications. Non-opioid medications used to treat FM at the standard doses in the community were permitted. Healthy controls were excluded if they had taken any pain medication other than an over the counter NSAID or acetaminophen within the last 1 month or for >1 month on a continual basis within the last 6 months.