Mindfulness-Based Stress Reduction (MBSR) and Chronic Neuropathic Pain (CNP): A Pilot fMRI Neuro-Imaging Analysis in Breast Cancer Survivors

A significant subset of women plagued with breast cancer continue to experience chronic neuropathic pain (CNP) long after undergoing cancer treatment. Medical interventions such as pharmacotherapy and/or surgery have been most widely used to abate painful symptoms with limited efficacy. Other alternatives are required given a heavy reliance on pharmaceuticals can lead to tolerance, dependence and severe side effects. Possibilities include cognitive behavioural therapy (CBT), physical therapy, and mindfulness interventions to supplement pharmacotherapies. Mindfulness practice in particular has been offered to a variety of chronic pain groups including breast cancer patients, however evidence is lacking to support its effectiveness in CNP for breast cancer survivors (BCS). The purpose of the present study was to explore the benefits a mindfulness-based stress reduction program (MBSR) may have on altering the underlying neuronal correlates linked with pain-related symptoms associated with CNP in BCS. The primary objective was to investigate how mindfulness training might possibly mediate the brain’s capacity for emotional reactivity, white matter integrity, and activation of the default mode network (DMN) and how these changes may correlate with levels of pain severity and pain interference, improving overall quality of life. To achieve these results, several brain imaging techniques were used in order to observe the correlation between the subjective experience of pain and the objective manifestation of brain changes that may be potentiated by MBSR training. A total of 23 participants were placed in either an 8 week MBSR intervention group (n=13) or a waitlist control group (n =10). All women were scanned with MRI before and after the 8 week intervention regardless of group allotment. The following neuroimaging modalities were used for each scanning session: resting state fMRI (rsfMRI) to monitor changes to functional connectivity in the default mode network (DMN); Diffusion Tensor Imaging (DTI) to assess the structural integrity of white matter tracts; and the Emotional Stroop Task (EST) to examine emotional reactivity in response to pain related stimuli. Exploratory results from this pilot study indicate that improvements to functional connectivity were apparent in the MBSR group relative to control, indicative of more efficient communication in areas related to attention, self-awareness, emotion regulation and pain. Improvements were also noted as increased cerebral white matter health and reduced emotional reactivity to pain related stimuli in the group of MBSR trained participants relative to control. Additionally, these functional and structural changes correlated with the self-reported pain measures in the MBSR group, suggesting that the MBSR group demonstrated improvements to ratings of pain severity and pain interference whereas the opposite occurred with the control group. The results have been interpreted as improvements to patients’ perception of pain and quality of life post MBSR training, however, were not limited to the subjective experience of pain. The inclusion of neuroimaging modalities provides objective and empirical support for MBSR training as it highlights the underlying brain mechanisms that were altered as part of MBSR treatment. Ultimately, the evidence suggests that MBSR could be incorporated as part of the treatment protocol for women experiencing CNP post breast cancer treatment.