The stress model of chronic pain: evidence from basal cortisol and hippocampal structure and function in humans

Abstract

Recent theories have suggested that chronic pain could be partly maintained by maladaptive physiological responses of the organism facing a recurrent stressor. The present study examined the associations between basal levels of cortisol collected over seven consecutive days, the hippocampal volumes and brain activation to thermal stimulations administered in 16 patients with chronic back pain and 18 healthy control subjects. Results showed that patients with chronic back pain have higher levels of cortisol than control subjects. In these patients, higher cortisol was associated with smaller hippocampal volume and stronger pain-evoked activity in the anterior parahippocampal gyrus, a region involved in anticipatory anxiety and associative learning. Importantly, path modelling-a statistical approach used to examine the empirical validity of propositions grounded on previous literature-revealed that the cortisol levels and phasic pain responses in the parahippocampal gyrus mediated a negative association between the hippocampal volume and the chronic pain intensity. These findings support a stress model of chronic pain suggesting that the sustained endocrine stress response observed in individuals with a smaller hippocampii induces changes in the function of the hippocampal complex that may contribute to the persistent pain states.

Altered Brain Complexity in Women with Primary Dysmenorrhea: A Resting-State Magneto-Encephalography Study Using Multiscale Entropy Analysis

“…Hippocampus is substantially involved in emotional learning, and parahippocampal gyrus is thought to be involved in stress-related disorders and anticipatory anxiety [121]. As long-term menstrual pain serves as a chronic stressor in life, this explains that the asymmetry of brain complexity in the parahippocampal gyrus was found to be positively associated with anxiety level in PDMs in this study.…”

Changes in Biochemical Markers of Pain Perception and Stress Response After Spinal Manipulation

“…4,44 Recent theories have also suggested that chronic pain could be partly maintained by maladaptive physiological responses of the organism facing a recurrent stressor, a situation related to high cortisol levels. 45,66 To our knowledge, there is a lack of studies analyzing changes in these nociception-related biochemical markers in response to manual therapy.…”

Mechanisms of Stress in Humans

“…Numerous studies have linked chronic stress to several health problems (e.g., Moffitt, 2013), including Parkinson's disease (in animal studies, e.g., Djamshidian & Lees, 2014;Sugama, et al, 2016), depression (e.g., Conway, Rutter & Brown, 2016;Gold, 2015;Swanson, Zeng, Weeks, & Colman, 2013) and pain (e.g., Hannibal & Bishop, 2014;Vachon-Presseau, 2013, Woda, Picard, & Dutheil, 2016. Stress was found to be associated with diminishing capacity to respond to reward (Admon, et al, 2013), declines in cognitive function (Vitaliano, et al, 2005) and disruptions in attentional control of the prefrontal cortex functions (Liston et al, 2009).…”