Pain Avoidance Behavior and Its Relation to Risk for Opioid Use in Chronic Pain Patients

Overall Research Design. The overarching goal of this study is to gain mechanistic insights into maladaptive pain avoidance behavior and risk factors that could provide a pathway for OUD in chronic pain patients. We aim to explore the neurophysiological constructs (brain oscillations) of the maladaptive pain avoidance behavior. Advancing this knowledge will open new opportunities for future clinical interventions to prevent opioid addiction in chronic pain patients. Aim-1 is based on a mechanistic framework termed predictive coding, and is designed to elicit cue-pain associative learning impairments that form the basis for maladaptive pain avoidance behavior in chronic pain patients. Aim-2 is designed to examine the influence of OUD related personality traits and risk factors in moderating maladaptive pain avoidance behavior. We strongly believe that aim-1 and 2 will aid the development of future clinical paradigms for early identification of patients vulnerable to OUD, treatment resistance and other psychodynamic factors that increase the risk for poor outcomes. Aim-3 further enhances the scope of the project by incorporating the study of brain oscillations during pain avoidance behavior that could help the development of non-addictive neuromodulation based interventions to promote extinction of learned maladaptive pain avoidance behavior.

Subjects. The study will evaluate patients with Complex Regional Pain Syndrome (CRPS) who present with central sensitization i.e. allodynia (pain response to a non-painful stimulus) and/or hyperalgesia (exaggerated pain response to a nociceptive stimulus), and age/gender matched healthy controls. The advantage of the CRPS model of chronic pain is that it is common and a common cause of post-injury disability. Additionally, patients typically present with an affected and non-affected extremity/site facilitating within-subject comparison. Patients will be considered candidates after review of their history, neurological and psychological pain assessment. Healthy controls will be recruited through fliers posted throughout our campus and by referrals from other studies.

Sample Size. Sample size is 30 patients and 30 age/gender-matched controls. The sample size was chosen based on the recommended power size for cue-based pain modulation studies.

Study Design. This cross-sectional study will present the participants with an instrumental pain avoidance learning task, while we record continuous MEG brain signals, and other autonomic measurements. All participants, upon initial screening and enrollment, will report to our MEG facility on the day of testing. They will undergo: 1) training to understand the task; 2) scalp measurements for head tracking inside the MEG scanner; and 3) actual testing in the MEG. A T1-weighted MRI (for anatomical co-registration of MEG data) will be acquired separately, if a suitable dataset is not already available.

Health History and clinical assessments. All patients will complete neuropsychological and pain assessments to rate their current pain, disability, fear, anxiety, and depression using standardized scales. In addition, we will administer Temperament and Character Inventory (TCI) questionnaire to assess the traits for aim-2.