Comorbid Chronic Pain and Posttraumatic Stress Disorder: Current Knowledge, Treatments, and Future Directions

Chronic pain is highly comorbid with posttraumatic stress disorder (PTSD), a disorder characterized by avoidance, hypervigilance, negative cognitions and affect, and intrusive symptoms (e.g., flashbacks), particularly among military personnel and those who are more vulnerable at developing this comorbid condition. This chapter describes the evolution of understanding pain from unidimensional Cartesian models to more complex models that culminated in the predominant contemporary biopsychosocial model, which accurately acknowledges that the experience of pain cannot be explained solely through the physical experience and that the physical experience is affected by factors seemingly unrelated to one's physical pain. This chapter also discusses two predominant theories that explain the chronic pain and PTSD comorbidity: the shared vulnerability model and the mutual maintenance model. The shared vulnerability model posits that anxiety sensitivity and genetic predispositions (particularly as they relate to the hypothalamic-pituitary-adrenal axis and stress response) make it more likely that certain individuals will develop this comorbidity. Similarly, the mutual maintenance model highlights seven different cognitive and emotional processes that form a shared mechanism of comorbidity: attentional biases, anxiety sensitivity, reminders of the traumatic experiences, avoidance, negative affect and decreased physical activity, negative perceptions of illness, and the inability to use effective coping strategies. This chapter examines the current state of these theories, discusses the existing treatments for comorbid pain and PTSD (both pharmacologic and nonpharmacologic), and offers suggestions on future directions for research and clinical care that may guide ongoing efforts to effectively treat these complex patient populations (e.g., a focus on patient identity).