Article published in Neuroscience & Biobehavioral Reviews, 37(8), 1549-1566 (September 2013; article #19).
This theoretical review highlights two misconceptions in the prevailing cognitive view of trauma-related disorders, specifically including PTSD. We see mental disorders such as PTSD as calling for mental explanations. In fact, trauma-related symptoms and disorders are inherently psychobiological. The bi-directional processes of psychoneuroimmunology explain why physical disorders are comorbid with stress. Diagnostic criteria for PTSD focus on sympathetically mediated "fight & flight" defenses, reflecting a belief that stems from Walter Cannon (1929, 1932). Actually, immobility defense states such as freeze and collapse are parasympathetically mediated; these immobility responses are preferred in situations of extreme threat (e.g., life-threat) when active defenses would increase the risk of death (e.g., in Complex PTSD). Together, active and immobility defense states contribute symptom variability that is neither predicted nor explained by the prevailing view. This evolutionary perspective has important implications for stress research, clinical practice, and diagnostic nosology.