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The Role Stress Plays In Chronic Pain

For sufferers, such as people who develop back pain after a car accident, avoiding the harmful effects of stress may be key to managing their condition. This is particularly important for people with a smaller-than-average hippocampus, as these individuals seem to be particularly vulnerable to stress. These are the findings of a study by Dr. , PhD in , Researcher at the Research Centre of the Institut universitaire de geriatrie de Montreal (IUGM) and Professor in the Faculty of Dentistry at Universite de Montreal, along with Etienne Vachon-Presseau, a PhD student in . The study appeared in Brain, a journal published by Oxford University Press.

“Cortisol, a hormone produced by the adrenal glands, is sometimes called the ‘stress hormone’ as it is activated in reaction to stress. Our study shows that a small hippocampal volume is associated with higher , which lead to increased vulnerability to pain and could increase the risk of developing pain chronicity,” explained Étienne Vachon-Presseau.

As Dr. Pierre Rainville described, “Our research sheds more light on the neurobiological mechanisms of this important relationship between stress and pain. Whether the result of an accident, illness or surgery, pain is often associated with high levels of stress Our findings are useful in that they open up avenues for people who suffer from pain to find treatments that may decrease its impact and perhaps even prevent chronicity. To complement their medical treatment, pain sufferers can also work on their and fear of pain by getting help from a psychologist and trying relaxation or meditation techniques.”

Research summary

This study included 16 patients with chronic back pain and a control group of 18 healthy subjects. The goal was to analyze the relationships between four factors: 1) cortisol levels, which were determined with saliva samples; 2) the assessment of clinical pain reported by patients prior to their brain scan (self-perception of pain); 3) hippocampal volumes measured with anatomical magnetic resonance imaging (MRI); and 4) brain activations assessed with functional MRI (fMRI) following thermal pain stimulations. The results showed that patients with chronic pain generally have higher cortisol levels than healthy individuals.

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. This study also supports stress management interventions as a treatment option for .


About the lead authors
Dr. Pierre Rainville, PhD in Neuropsychology, Researcher at the Research Centre of the IUGM
Director of the Laboratory of the Neuropsychophysiology of Pain
Full Professor, Department of Stomatology, Faculty of Dentistry, Université de Montréal
Groupe de recherche sur le système nerveux central (GRSNC), Université de Montréal
Étienne Vachon-Presseau, PhD student in Neuropsychology, Department of Psychology, Université de Montréal
Étienne Vachon-Presseau, Mathieu Roy, Marc-Olivier Martel, Etienne Caron, Marie-France Marin, Jeni Chen, Geneviève Albouy, Isabelle Plante, Michael J. Sullivan, Sonia J. Lupien et Pierre Rainville. “The stress model of chronic pain: evidence from basal cortisol and hippocampal structure and function in humans”, February 18, 2013.
University of Montreal