The Relations Between Childhood Trauma, Cortisol Levels, and Pain Perceptions in Response to Induced Thermal Pain in Fibromyalgia Patients
Childhood trauma has been linked to an increased risk of chronic pain in adulthood. One potential mechanism is via childhood trauma's impact on the hypothalamic-pituitary-adrenal axis (HPA) response to stress, reflected in changes in salivary cortisol levels (Nicolson et al., 2010). This study sought to determine the relations between childhood trauma, increases in cortisol levels following induced pain, and pain perceptions in adults with fibromyalgia, a chronic pain condition. It drew on data collected from participants enrolled in an investigation comparing the effectiveness of behavioral treatments for chronic pain. Before receiving treatment, participants attended a laboratory session during which they first rested, and then were exposed to heat stimuli to assess pain threshold and tolerance. Saliva samples were collected from each participant immediately following the rest, and twice during pain induction. Fibromyalgia participants with a history of childhood trauma were expected: 1) to report lower pain threshold and tolerance levels (i.e., have higher pain sensitivity), 2) to exhibit a higher resting cortisol level, and 3) to have greater increases in cortisol in response to acute pain induction than fibromyalgia participants without a history of childhood trauma. Findings showed that childhood trauma scores were: 1) related to lower pain tolerance (but not pain threshold), 2) unrelated to resting cortisol levels, and 3) unrelated to changes in cortisol in response to pain induction and pain tolerance, contrary to prediction. However, a subtype of childhood trauma, i.e., emotional maltreatment: 1) predicted lower pain tolerance, and 2) moderated the cortisol changes over time in response to pain induction during the laboratory session in the expected direction. That is, individuals who reported higher levels of childhood emotional maltreatment showed greater cortisol responses to the pain induction than individuals who reported lower levels of exposure to emotional maltreatment. Cortisol responses did not relate to pain perception. Thus, childhood emotional trauma predicted greater pain sensitivity and cortisol reactivity, but cortisol did not relate to pain perception. The findings suggest that early childhood trauma predicts cortisol reactivity and pain sensitivity, but that cortisol reactivity is not a mediator in the trauma-pain relation.