Posttraumatic Stress Disorder (PTSD)
Authors: Brewin Chris R. 
Published: March 2013

Severe reactions to experiences such as combat and railway accidents have been described since the mid-19th century by numerous physicians, including Sigmund Freud and Pierre Janet. These descriptions include two types of characteristic symptoms: dissociative symptoms, in which there is a general disturbance in normal mental functions, such as memory, consciousness, time estimation, sense of reality, and identity, and reexperiencing symptoms, in which the traumatic event is vividly relived as though it were happening all over again in the present. Despite this early recognition, posttraumatic stress disorder (PTSD) was formally defined only in the third edition of the American Psychiatric Association’s Diagnostic and Statistical Manual of Mental Disorders: DSM-III (Washington, DC: American Psychiatric Association, 1980). Prior to this, exposure to stress was assumed to produce only short-term problems in adjustment. In the DSM-III, PTSD required exposure to “a recognizable stressor that would evoke significant symptoms of distress in almost everyone” (p. 238) and was “outside the range of normal human experience” (p. 236). In addition four symptoms had to be present reflecting reexperiencing of the traumatic event, numbing and detachment, and a more pervasive change in arousal or emotions. The introduction of the disorder in the DSM-III was strongly influenced by studies of combat veterans and women in violent relationships, which suggested the existence of more long-lasting psychiatric conditions, variously termed “combat neurosis,” “rape trauma syndrome,” or “battered women syndrome.” The PTSD diagnosis was designed to subsume these syndromes and capture what was considered to be an essentially normal response to any overwhelming trauma. This made it unlike other psychiatric disorders, which all implied some vulnerability on the part of the person who succumbed to it. The definition was refined in the Diagnostic and Statistical Manual of Mental Disorders: DSM-III-R published in 1987, which introduced more symptoms and required at least one reexperiencing symptom (e.g., intrusive memories or nightmares), three avoidance or numbing symptoms (e.g., avoidance of reminders of the traumatic event or loss of interest in activities), and two hyperarousal symptoms (e.g., exaggerated startle or irritability). Diagnostic and Statistical Manual of Mental Disorders: DSM-IV, introduced in 1994, retained a similar structure. The 2013 Diagnostic and Statistical Manual of Mental Disorders: DSM-5 increased the number of symptoms from seventeen to twenty and reorganized them into four symptom clusters, reexperiencing, avoidance, negative alterations in cognition and mood, and alterations in arousal and reactivity. In 1992 PTSD also appeared in another major international classification system, the tenth edition of the World Health Organization’s International Classification of Diseases (ICD-10) (Geneva, Switzerland: World Health Organization, 1992–1994). This formulation placed more emphasis on “episodes of repeated reliving of the trauma in intrusive memories (‘flashbacks’) or dreams” and also identified avoidance, numbing, and hyperarousal as central features. International Classification of Diseases (ICD-11) (Geneva, Switzerland: World Health Organization, 2019) greatly simplified the PTSD diagnosis, requiring one out of two reexperiencing symptoms, one out of two avoidance symptoms, and one out of two sense of threat symptoms, along with impairment in functioning.