Definition and epidemiology
Post-traumatic stress disorder (PTSD) is a trauma- and stressor-related disorder characterized by the development of specific symptoms following exposure to one or more traumatic events. According to DSM-5 criteria, the traumatic event must involve actual or threatened death, serious injury, or sexual violence experienced directly, witnessed, or learned about when occurring to a close family member or friend.
The lifetime prevalence of PTSD in the general United States population is approximately 6-8%, with 12-month prevalence around 3-4%. Women are twice as likely as men to develop PTSD (10-12% vs 5-6% lifetime prevalence). The disorder can occur at any age, including childhood, but onset typically follows the traumatic event by days to months.
High-risk populations include:
- Combat veterans (10-30% prevalence)
- Survivors of sexual assault (approximately 50% develop PTSD)
- Refugees and torture survivors
- First responders and emergency personnel
- Victims of severe motor vehicle accidents
- Individuals exposed to natural disasters
Not everyone exposed to trauma develops PTSD; approximately 50-60% of the population experiences at least one traumatic event, but only a minority develops the disorder.
- PTSD requires trauma exposure plus symptoms from 4 clusters (intrusion, avoidance, negative cognition/mood, hyperarousal) lasting >1 month
- Flashbacks are dissociative reactions where the person re-experiences the trauma as if it is happening now
- Acute stress disorder (<1 month duration) can progress to PTSD if symptoms persist beyond 1 month
- Trauma-focused CBT and EMDR are first-line psychotherapies; SSRIs (sertraline, paroxetine) are first-line medications
- Benzodiazepines are NOT recommended for PTSD—they do not prevent or treat PTSD and may impair psychotherapy
- PTSD has 50% comorbidity with major depression and 30-50% with substance use disorders
- Women have twice the lifetime prevalence of PTSD compared to men despite lower trauma exposure rates
- Sexual assault has the highest conditional risk (~50%) for developing PTSD among trauma types
Etiology and risk factors
PTSD develops through a complex interaction of biological, psychological, and social factors. The essential etiological requirement is exposure to a qualifying traumatic event, but additional risk factors determine who develops the disorder.
Pre-trauma risk factors:
- Prior psychiatric history (especially depression, anxiety disorders)
- Childhood adversity or previous trauma exposure
- Family history of psychiatric disorders
- Female sex
- Lower socioeconomic status
- Lower education level
- Younger age at time of trauma
- Genetic factors (heritability estimated at 30-40%)
Peri-trauma risk factors:
- Severity and duration of trauma exposure
- Interpersonal violence (especially sexual assault)
- Perceived life threat
- Dissociation during the traumatic event
- Physical injury during trauma
- Witnessing atrocities or death
Post-trauma risk factors:
- Lack of social support
- Additional life stressors
- Acute stress disorder symptoms
- Ongoing threat or reminders
- Physical pain or disability
- Financial or legal problems
The type of trauma influences PTSD risk. Interpersonal violence, particularly sexual assault, carries the highest conditional risk (approximately 50%), followed by combat exposure (10-30%), motor vehicle accidents (10-20%), and natural disasters (5-10%).
Pathophysiology
PTSD involves dysregulation of multiple neurobiological systems responsible for threat detection, emotional regulation, and memory processing.
Neuroanatomical findings:
- Amygdala hyperactivity: Increased reactivity to threat-related stimuli, contributing to hyperarousal and fear responses
- Prefrontal cortex hypofunction: Reduced activity in the medial prefrontal cortex and anterior cingulate cortex, impairing fear extinction and emotional regulation
- Hippocampal volume reduction: Smaller hippocampal volumes associated with impaired contextual memory processing and inability to distinguish safe from dangerous contexts
- Altered insula function: Disrupted interoceptive awareness and emotional processing
Neuroendocrine dysregulation:
- Hypothalamic-pituitary-adrenal (HPA) axis abnormalities with paradoxically low cortisol levels and enhanced negative feedback sensitivity
- Elevated catecholamine levels (norepinephrine, epinephrine)
- Dysregulated corticotropin-releasing hormone (CRH) signaling
Neurotransmitter systems:
- Noradrenergic hyperactivity: Increased sympathetic tone contributing to hyperarousal symptoms
- Serotonergic dysfunction: Reduced serotonin associated with intrusive thoughts and mood symptoms
- GABAergic deficits: Reduced inhibitory tone contributing to anxiety and hypervigilance
- Glutamatergic dysregulation: NMDA receptor involvement in fear learning and memory consolidation
Fear conditioning model: PTSD can be understood as impaired fear extinction. The traumatic memory becomes over-consolidated and fails to extinguish despite absence of threat. Context-dependent fear discrimination is impaired, leading to generalized fear responses to trauma reminders.
Clinical features
DSM-5 diagnostic criteria require exposure to a traumatic event plus symptoms from four clusters persisting for more than one month and causing significant distress or functional impairment.
Criterion A: Trauma exposure
Direct experience, witnessing, learning it occurred to a close relation, or repeated/extreme exposure to aversive details (e.g., first responders). Media exposure alone does not qualify unless work-related.
Criterion B: Intrusion symptoms (≥1 required)
- Intrusive memories: Recurrent, involuntary, distressing recollections
- Nightmares: Distressing dreams with content/affect related to trauma
- Flashbacks: Dissociative reactions where the individual feels or acts as if the trauma is recurring (can range from brief episodes to complete loss of awareness)
- Psychological distress at exposure to trauma reminders
- Physiological reactivity to trauma cues (tachycardia, sweating, tremor)
Criterion C: Avoidance (≥1 required)
- Avoidance of distressing trauma-related thoughts, feelings, or memories
- Avoidance of external reminders (people, places, conversations, activities, objects, situations)
Criterion D: Negative alterations in cognition and mood (≥2 required)
- Inability to recall key features of the trauma (dissociative amnesia)
- Persistent negative beliefs about oneself, others, or the world ("I am bad," "No one can be trusted," "The world is dangerous")
- Distorted blame of self or others for causing the trauma
- Persistent negative emotional state (fear, horror, anger, guilt, shame)
- Diminished interest in significant activities
- Detachment or estrangement from others
- Persistent inability to experience positive emotions (anhedonia)
Criterion E: Alterations in arousal and reactivity (≥2 required)
- Irritable behavior and angry outbursts
- Reckless or self-destructive behavior
- Hypervigilance
- Exaggerated startle response
- Concentration problems
- Sleep disturbance
Subtypes:
- With dissociative symptoms: Depersonalization (detachment from self) or derealization (surroundings seem unreal)
- With delayed expression: Full criteria not met until at least 6 months after trauma
Associated features include suicidal ideation, substance abuse, somatic symptoms (chronic pain, gastrointestinal complaints), and high rates of comorbid depression and anxiety disorders.
Diagnosis
PTSD is a clinical diagnosis based on history and mental status examination. There are no diagnostic laboratory tests or imaging studies.
Diagnostic criteria (DSM-5):
All of the following must be present:
- Exposure to actual or threatened death, serious injury, or sexual violence (Criterion A)
- ≥1 intrusion symptom (Criterion B)
- ≥1 avoidance symptom (Criterion C)
- ≥2 negative alterations in cognition and mood (Criterion D)
- ≥2 alterations in arousal and reactivity (Criterion E)
- Duration >1 month (Criterion F)
- Clinically significant distress or functional impairment (Criterion G)
- Not attributable to substance use or medical condition (Criterion H)
Clinical assessment:
- Comprehensive psychiatric history: Detailed trauma history, symptom timeline, prior psychiatric disorders
- Mental status examination: Observe for hypervigilance, restricted affect, dissociation, evidence of re-experiencing during interview
- Functional assessment: Impact on work, relationships, daily activities
- Suicide risk assessment: PTSD significantly increases suicide risk
- Substance use screening: High comorbidity with alcohol and drug use disorders
Standardized instruments (for severity assessment, not diagnosis):
- Clinician-Administered PTSD Scale (CAPS-5)
- PTSD Checklist for DSM-5 (PCL-5)
- Impact of Event Scale-Revised (IES-R)
Medical workup to exclude organic causes:
- Thyroid function tests (hyperthyroidism can mimic anxiety/hyperarousal)
- Substance use screening
- Neurological examination if head injury occurred during trauma
Timing considerations:
- Symptoms lasting <1 month after trauma: Acute stress disorder (not PTSD)
- Symptoms developing ≥6 months after trauma but meeting all other criteria: PTSD with delayed expression
Differential diagnosis
Acute stress disorder (ASD): Symptoms occur within 3 days to 1 month after trauma. If symptoms persist beyond 1 month, diagnosis changes to PTSD. ASD requires ≥9 symptoms from intrusion, negative mood, dissociation, avoidance, and arousal categories.
Adjustment disorder: Develops in response to a stressor that does not meet Criterion A for trauma exposure (e.g., job loss, divorce, relocation). Symptoms are distressing but do not include the full PTSD symptom clusters.
Major depressive disorder: Shares symptoms of anhedonia, social withdrawal, sleep disturbance, and concentration problems. Key distinction is the absence of trauma-related intrusion and avoidance symptoms in pure depression. High comorbidity (approximately 50% of PTSD patients have comorbid depression).
Generalized anxiety disorder: Excessive worry and hyperarousal, but anxiety is not trauma-focused and lacks intrusion symptoms or specific avoidance of trauma reminders.
Panic disorder: Can include hyperarousal, physiological reactivity, and avoidance behavior, but panic attacks are not specifically triggered by trauma reminders and lack the intrusive re-experiencing component.
Obsessive-compulsive disorder: Intrusive thoughts in OCD are recognized as one's own mental productions (ego-dystonic obsessions), whereas PTSD intrusions are experienced as re-experiencing the actual trauma. OCD compulsions are repetitive behaviors, not avoidance of trauma reminders.
Traumatic brain injury (TBI): Commonly comorbid with PTSD (especially in combat veterans and assault victims). TBI causes cognitive impairment, personality changes, and emotional lability. Both conditions can coexist. Neuropsychological testing helps distinguish cognitive impairment from PTSD symptoms.
Dissociative disorders: Dissociative amnesia, depersonalization/derealization disorder, and dissociative identity disorder involve prominent dissociative symptoms. In PTSD, dissociation is specifically related to trauma reminders. Dissociative disorders may develop after chronic childhood trauma.
Substance use disorders: Can cause anxiety, sleep disturbance, and mood symptoms. Detailed timeline helps distinguish whether substance use preceded symptoms or developed as self-medication for PTSD.
Personality disorders: Borderline and paranoid personality disorders may share features of emotional instability, relationship problems, and hypervigilance. Personality disorders represent longstanding patterns predating any trauma, though complex PTSD with personality changes can occur after chronic trauma.
Psychotic disorders: Flashbacks in PTSD are distinct from hallucinations in that the individual typically recognizes them as memories (though severe flashbacks may temporarily obscure reality testing). Psychotic disorders lack the specific link to trauma.
Management
Treatment combines trauma-focused psychotherapy with pharmacotherapy. Psychotherapy is considered first-line treatment, with medications as adjuncts.
Psychotherapy
First-line evidence-based therapies:
Trauma-focused cognitive behavioral therapy (TF-CBT): 8-16 weekly sessions focusing on:
- Psychoeducation about trauma and PTSD
- Anxiety management skills (relaxation, breathing)
- Cognitive restructuring of trauma-related thoughts
- Gradual imaginal and in vivo exposure to trauma memories and reminders
- Processing of trauma narrative
TF-CBT has the strongest evidence base with approximately 60% of patients no longer meeting PTSD criteria after treatment.
Prolonged exposure (PE) therapy: 8-15 sessions involving:
- Repeated, prolonged imaginal exposure to trauma memories
- In vivo exposure to avoided trauma-related situations
- Processing emotional responses
Particularly effective for avoidance symptoms.
Cognitive processing therapy (CPT): 12 sessions addressing:
- Stuck points in trauma processing
- Challenging maladaptive beliefs about safety, trust, control, esteem, intimacy
- Written trauma accounts
Effective for addressing cognitive distortions.
Eye movement desensitization and reprocessing (EMDR): 8-12 sessions using:
- Bilateral stimulation (eye movements, tapping)
- While processing trauma memories
- No prolonged exposure or detailed trauma narrative required
Comparable efficacy to CBT approaches.
Other evidence-based approaches:
- Narrative exposure therapy
- Present-centered therapy
- Stress inoculation training
Pharmacotherapy
First-line medications (FDA-approved for PTSD):
- Sertraline: SSRI, start low, titrate based on response
- Paroxetine: SSRI, particularly effective for anxiety symptoms
Other SSRIs (fluoxetine, escitalopram) and SNRIs (venlafaxine) are also effective though not FDA-approved for PTSD.
Second-line medications:
- Prazosin: Alpha-1 antagonist for trauma-related nightmares (though recent large trials have questioned efficacy)
- Other antidepressants: Mirtazapine, nefazodone (monitor for hepatotoxicity)
Adjunctive medications for specific symptoms:
- Short-term benzodiazepines are not recommended (no evidence of benefit, risk of dependence, may impair psychotherapy)
- Atypical antipsychotics (risperidone, quetiapine) for severe hyperarousal or comorbid psychosis (limited evidence)
- Mood stabilizers for irritability and anger (limited evidence)
Medication principles:
- Adequate trial is 8-12 weeks at therapeutic dose
- Continue for at least 12 months after response
- Taper gradually to assess need for continuation
- Medications reduce symptom severity approximately 20-30% but rarely achieve full remission alone
Combined treatment
Combining trauma-focused psychotherapy with SSRIs/SNRIs may be more effective than either alone, particularly for severe PTSD or comorbid depression.
Additional interventions
- Group therapy: Peer support, normalize experiences, reduce isolation
- Family therapy: Address relationship problems, psychoeducation for family members
- Complementary approaches: Yoga, mindfulness-based stress reduction (emerging evidence)
- Inpatient treatment: For severe cases with suicidality, severe comorbidity, or failure of outpatient treatment
Treatment resistance
- Reassess diagnosis and comorbidities (especially substance use, TBI)
- Ensure adequate psychotherapy dose and fidelity
- Optimize medication dosing
- Address ongoing stressors and social support
- Consider alternative psychotherapies
- Manage comorbid conditions
Complications and prognosis
Complications:
Psychiatric comorbidities (present in 80-90% of PTSD patients):
- Major depressive disorder (50% comorbidity)
- Substance use disorders (30-50%)
- Other anxiety disorders (panic disorder, generalized anxiety disorder)
- Suicidal ideation and attempts (significantly elevated risk)
Physical health complications:
- Cardiovascular disease (increased risk of hypertension, coronary artery disease, stroke)
- Chronic pain syndromes
- Gastrointestinal disorders (irritable bowel syndrome)
- Metabolic syndrome and obesity
- Immune dysfunction and increased infection risk
- Premature mortality
Psychosocial complications:
- Occupational impairment and unemployment
- Relationship dysfunction and divorce
- Domestic violence (as victim or perpetrator)
- Homelessness (especially in veteran populations)
- Legal problems
- Social isolation
Prognosis:
PTSD has a variable course:
Spontaneous remission: Approximately 30-40% of cases resolve spontaneously within the first year after trauma, even without treatment. However, symptoms lasting beyond 1 year are less likely to remit without intervention.
Chronic course: Without treatment, 30-40% of patients have chronic symptoms lasting years to decades. Chronic PTSD is more common with:
- Severe trauma exposure
- Interpersonal violence
- Lack of social support
- Comorbid disorders
- Delayed or inadequate treatment
With treatment: Evidence-based psychotherapy leads to:
- 50-70% response rate (significant symptom reduction)
- 30-50% remission rate (no longer meeting diagnostic criteria)
- Gains typically maintained at long-term follow-up
Predictors of better prognosis:
- Rapid access to treatment
- Good social support
- Absence of comorbid disorders
- Single-incident trauma (vs. chronic trauma)
- Higher education and socioeconomic status
- Adaptive coping strategies
- No ongoing stressors
Predictors of worse prognosis:
- Childhood trauma or adverse childhood experiences
- Chronic or repeated trauma
- Dissociative symptoms
- Comorbid substance use
- Severe symptom severity at presentation
- Lack of social support
- Ongoing stressors or threat
- Delayed treatment
Long-term outcomes: Even with successful treatment, some patients experience residual symptoms or relapse during subsequent stressors. Ongoing monitoring and booster sessions may be helpful.
Trauma symptoms 4 C's: Criterion B = re-experienCing (intrusions), Criterion C = avoidanCe, Criterion D = Cognition/mood changes, Criterion E = arousal Changes (formerly hyperarousal was C, but DSM-5 criteria order is B-C-D-E)
Practice questions
1. A 28-year-old war veteran presents with disturbing nightmares and intrusive memories of combat for the past 3 months. He avoids watching war movies, has lost interest in activities he previously enjoyed, and startles easily at loud noises. He reports difficulty concentrating at work and has frequent angry outbursts. He denies substance use. Which of the following is the most appropriate initial treatment?
2. A 35-year-old woman with a history of sexual assault 6 months ago presents with recurrent distressing memories of the event. She actively avoids the area where the assault occurred and has stopped dating. She reports feeling emotionally numb, blames herself for the assault, and believes the world is completely dangerous. She has difficulty falling asleep and is constantly 'on edge.' Physical examination is unremarkable. In addition to psychotherapy, which medication is most appropriate?
3. A 42-year-old man presents 2 weeks after a severe motor vehicle accident in which his passenger died. He reports vivid flashbacks of the crash, avoids driving, feels detached from his family, has nightmares, and is hypervigilant. He states 'I should have prevented it' despite not being at fault. Mental status exam shows restricted affect and increased startle response. Which of the following is the most likely diagnosis?
Frequently asked questions
What causes PTSD?
PTSD is caused by exposure to actual or threatened death, serious injury, or sexual violence. Not everyone exposed to trauma develops PTSD—only about 10-20% of those experiencing trauma will develop the disorder. Risk factors include trauma severity, prior psychiatric history, lack of social support, female sex, childhood adversity, and genetic vulnerability. The highest risk comes from interpersonal violence, especially sexual assault (approximately 50% conditional risk).
What are the first symptoms of PTSD?
The first symptoms typically include intrusive re-experiencing of the trauma through flashbacks, nightmares, or distressing memories that feel vivid and uncontrollable. Many people also develop hypervigilance, exaggerated startle responses, and sleep disturbances within days to weeks after the trauma. Avoidance of trauma reminders often develops as the person tries to prevent triggering these distressing intrusions. If symptoms last less than one month, it is called acute stress disorder; PTSD is diagnosed when symptoms persist beyond one month.
How is PTSD diagnosed?
PTSD is diagnosed clinically based on the DSM-5 criteria after detailed psychiatric interview. The diagnosis requires documented trauma exposure plus at least one intrusion symptom (like flashbacks), one avoidance symptom, two negative changes in thoughts and mood, and two hyperarousal symptoms, all lasting more than one month and causing significant impairment. There are no blood tests or brain scans that diagnose PTSD. Standardized questionnaires like the PTSD Checklist (PCL-5) help assess symptom severity but do not replace clinical diagnosis.
Is PTSD curable?
PTSD is treatable and many people achieve full remission, though 'cure' implies permanent resolution which cannot be guaranteed. Evidence-based psychotherapies like trauma-focused CBT and EMDR lead to remission in 30-50% of patients and significant improvement in 50-70%. Approximately 30-40% of cases resolve spontaneously in the first year. With treatment, most people experience substantial symptom reduction and functional improvement, though some have residual symptoms or relapse during future stressors. Early, appropriate treatment significantly improves long-term outcomes.
PTSD vs acute stress disorder—what is the difference?
The primary difference is duration: acute stress disorder (ASD) occurs within 3 days to 1 month after trauma, while PTSD requires symptoms lasting more than 1 month. Both involve trauma exposure and similar symptoms (intrusions, avoidance, negative mood, hyperarousal). ASD specifically requires at least 9 symptoms across the categories and emphasizes dissociative symptoms. If ASD symptoms persist beyond one month, the diagnosis changes to PTSD. About 50% of people with ASD will progress to PTSD.
Key drugs
Related conditions and differentials
Sources and further reading
StatPearls (NCBI Bookshelf)MedlinePlusWHO ICD-10: F43.1
Educational content for medical students, prepared by the WhiteCoat Pro editorial team with AI assistance; every page is reviewed by a second AI model for factual errors. It is not medical advice and does not replace the product label, local guidelines or a clinician.