Posted on Mar 18, 2013, 6 a.m.
For chronic pain sufferers, avoiding the harmful effects of stress may be key to managing their condition.
Some evidence suggests that chronic pain could be partly maintained by maladaptive physiological responses when faced with a recurrent stressor. Etienne Vachon-Presseau, from the University of Montreal (Canada), and colleagues examined the associations between basal levels of cortisol – an adrenal hormone associated with the stress response – 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. Data analysis revealed that patients with a smaller hippocampus have higher cortisol levels and stronger responses to acute pain in a brain region involved in anticipatory anxiety in relation to pain. The response of the brain to the painful procedure during the scan partly reflected the intensity of the patient's current clinical pain condition. These findings support the chronic pain vulnerability model in which people with a smaller hippocampus develop a stronger stress response, which in turn increases their pain and perhaps their risk of suffering from chronic pain. The study authors conclude that: “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.”
Etienne Vachon-Presseau, Mathieu Roy, Marc-Olivier Martel, Etienne Caron, Marie-France Marin, Pierre Rainville, et al. “The stress model of chronic pain: evidence from basal cortisol and hippocampal structure and function in humans.” Brain (2013) 136(3): 815-827.