Post-Traumatic Stress Disorder

Post-traumatic stress disorder (PTSD) is a condition that can develop after exposure to actual or threatened death, serious injury, or sexual violence. It is characterized by intrusive re-experiencing of the trauma (such as memories, nightmares, or flashbacks), avoidance of trauma reminders, persistent negative alterations in mood and cognition, and marked hyperarousal. In DSM-5 PTSD belongs to a distinct chapter of trauma- and stressor-related disorders, defined by its requirement of an identifiable traumatic event.

Definition

Post-traumatic stress disorder is a condition arising after exposure to a traumatic event and defined by four symptom clusters - intrusion (re-experiencing), avoidance of trauma-related stimuli, negative alterations in cognitions and mood, and alterations in arousal and reactivity - persisting for more than one month and causing clinically significant distress or impairment.

Scope

This entry covers the clinical features and symptom clusters of PTSD, the fear-learning and memory mechanisms thought to underlie it, its epidemiology and conditional risk after trauma, and the evidence base for trauma-focused psychological treatment. It is reference-educational and does not provide individual diagnostic or treatment guidance.

Core questions

• What kinds of events qualify as the traumatic stressor, and why does the diagnosis require one?
• Why do only some people exposed to trauma develop PTSD?
• How do fear conditioning, impaired extinction, and memory processes maintain symptoms?
• What treatments have the strongest evidence in PTSD?

Key concepts

• Traumatic event (Criterion A)
• Intrusive re-experiencing and flashbacks
• Avoidance
• Negative alterations in cognition and mood
• Hyperarousal
• Impaired fear extinction
• Trauma-focused therapy

Key theories

Emotional processing theory

Foa and Kozak's emotional-processing account holds that pathological fear is stored as a network that must be activated and updated with corrective, disconfirming information for recovery to occur; this provides the rationale for trauma-focused exposure, which activates the trauma memory under safe conditions to allow new learning.

Mechanisms

PTSD is conceptualized as a disorder of fear learning and memory in which a trauma memory is encoded with strong emotional salience and inadequately contextualized, so that reminders trigger intense re-experiencing and arousal. Impaired extinction learning and deficient prefrontal regulation of an over-reactive amygdala are central neurobiological hypotheses, alongside dysregulation of stress-hormone systems. Emotional-processing models frame recovery as the updating of the fear memory with corrective information, the basis of exposure-based treatment.

Clinical relevance

PTSD can be chronic and disabling, commonly co-occurs with depression and substance use, and is encountered across general medical, emergency, and specialty settings after traumatic events. This entry describes how the disorder is defined and studied to support understanding and evidence appraisal; it is not a basis for diagnosing or treating any individual.

Epidemiology

Although traumatic-event exposure is common, only a minority of those exposed develop PTSD, with conditional risk varying by trauma type - higher after interpersonal and sexual violence than after many other events. Lifetime prevalence in general populations is several percent, with a female preponderance, and high comorbidity with depression and substance-use disorders.

Evidence & guidelines

Trauma-focused cognitive behavioral therapies - including prolonged exposure and cognitive processing therapy - have the strongest evidence, with meta-analytic support for prolonged exposure; serotonergic medications are an established pharmacological option. DSM-5-TR places PTSD in the trauma- and stressor-related disorders chapter and ICD-11 codes it 6B40 (with a separate complex PTSD category); this entry summarizes the evidence base rather than recommending a regimen.

History

Reactions to overwhelming events have been described under many names - from 'soldier's heart' and 'shell shock' to 'combat fatigue' - but PTSD entered formal nosology in DSM-III (1980), prompted substantially by clinical observations among combat veterans and survivors of other traumas. Successive revisions refined the stressor criterion and symptom structure, and DSM-5 (2013) moved PTSD out of the anxiety disorders into a dedicated trauma- and stressor-related chapter.

Debates

How should the traumatic-stressor criterion (Criterion A) be defined?

There is ongoing debate over how narrowly to define qualifying events, since broadening the criterion risks diluting the construct while narrowing it may exclude people with genuine trauma-related symptoms; DSM-5 retained a defined event requirement that distinguishes PTSD from other disorders.

Key figures

• Edna Foa
• Arieh Shalev
• Richard Bryant
• Israel Liberzon
• Charles Marmar

Seminal works

• foa-kozak-1986
• powers-2010
• shalev-2017

Frequently asked questions

Does everyone exposed to a traumatic event develop PTSD?

No. Most people exposed to trauma do not develop PTSD; the conditional risk depends on the type of event and other factors, and is higher after interpersonal and sexual violence than after many other traumatic events.

What are the core symptom clusters of PTSD?

DSM-5-TR defines four clusters: intrusive re-experiencing (memories, nightmares, flashbacks), avoidance of trauma reminders, negative alterations in cognition and mood, and alterations in arousal and reactivity, persisting more than one month with significant distress or impairment.