Posttraumatic Stress Disorder (PTSD)

Posttraumatic stress disorder is a psychiatric illness characterized by overwhelming stress and anxiety experienced after exposure to a life-threatening event. Symptoms last more than 1 month and involve re-experiencing the event as flashbacks or nightmares, avoiding reminders of the event, irritability, hyperarousal, and poor memory and concentration. Treatment is mainly based on CBT and eye movement desensitization. Pharmacological regimens, such as antidepressants, might be indicated in some cases.

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Posttraumatic stress disorder is a severe, chronic psychiatric disorder that develops after experiencing or witnessing a traumatic event. The response to the trauma lasts more than 1 month and often includes severe fear manifesting as intrusive thoughts, flashbacks, or nightmares, which in turn negatively impact the patient’s life.


  • Estimated prevalence in the United States: approximately 8%–10%  (under-reported, as approximately 60% report experiencing significant trauma) 
  • Risk factors related to the development of PTSD:
    • Gender: Women are more likely to develop PTSD. 
    • Stressor: 
      • Sexual assault: most common cause in women
      • Combat trauma: most common cause in men
  • Diagnosed in all age groups but most prevalent among young adults
  • ⅔ have other comorbid disorders: 
    • Mood disorders
    • Substance use disorders
    • Anxiety disorders

Etiology and pathophysiology

Alterations in brain physiology:

  • Many symptoms explained by an alteration in limbic system:
    • Amygdala (highly sensitive to trauma-related stimuli)
    • Hippocampus
    • Medial frontal cortex
  • Orbitofrontal cortex: 
    • Normally inhibits overactivation of limbic system regions 
    • Patients show decreased inhibition by orbitofrontal cortex.
PTSD brain

Brain regions that are affected by PTSD

Image: “PTSD brain” by The National Institute of Mental Health (NIMH). License: Public Domain

Alteration in functioning of neuro-hormonal and neuro-transmitter functioning:

  • Hypothalamic-pituitary-adrenal (HPA) axis: 
    • HPA axis is hyper-regulated in PTSD.
    • Low plasma and urinary free cortisol concentrations found in those with PTSD
  • Noradrernergic system:
    • Patients with PTSD may exhibit not only anxiety, but also increased blood pressure, heart rate, palpitations, sweating, and tremors.
    • Increased 24-hour urine epinephrine concentration in those with PTSD
Major neurobiological processes in PTSD

Major neurobiological processes in PTSD:
HPA: hypothalamic-pituitary-adrenal
mPFC: medial prefrontal cortex

Image by Lecturio. License: CC BY-NC-SA 4.0

Clinical Presentation and Diagnosis

Traumatic event

  • E.g., threat of death, severe harm, or sexual assault
  • Exposure:
    • The patient personally experiences the traumatic event.
    • The patient witnesses a traumatic event affecting another person.
    • The patient learns about a close contact (family/friend) being exposed to trauma. 
    • Indirect exposure to details of trauma (e.g., first responders)
    • Exposure through media, pictures, or electronic devices does not qualify as trauma.

Diagnosis through clinical criteria

  • Intrusion symptoms:
    • Recurring, distressing, and involuntary memories from trauma 
    • Recurring nightmares related to trauma 
    • Dissociative reactions, such as flashbacks, in which the patient feels as if they are re-experiencing trauma
    • Marked physiological or psychological reaction to exposure to internal/external cues that resemble trauma 
  • Avoidance behavior:
    • Avoidance of memories related to traumatic event
    • Avoidance of places/people that may trigger memories of traumatic event
  • Negative mood changes:
    • Inability to remember an important aspect of triggering event
    • Persistent negative beliefs about oneself
    • Distorted thoughts about cause of event
    • Persistent negative emotional state
    • Markedly diminished interest in participation in daily activities
    • Feeling of isolation and inability to experience positive emotions
  • Altered arousal:
    • Anger outbursts
    • Self-destructive behavior
    • Hypervigilance
    • Difficulty concentrating
    • Excessive startle reaction
    • Sleep disturbances
  • Duration and impact on life:
    • Symptoms must be present > 1 month.
    • Symptoms should significantly impair quality of life.
    • The use of mood-altering substances must be excluded.

Other tests

Diagnosis is clinical. Laboratory investigations or imaging studies are performed to exclude other medical conditions or for research purposes.

  • Laboratory investigations might show: 
    • Decrease in cortisol levels 
    • Elevated levels of norepinephrine and epinephrine
    • Elevated levels of endogenous opiates, which are related to blunted emotions 
  • MRI studies might show:
    • Hippocampal atrophy
    • Decreased corpus callosum size
    • Decreased prefrontal cortex size and action 
    • Increased amygdala reactivity



  • Inhibit brain regions known to cause symptoms 
  • Shortens course of recovery
  • Trauma-oriented CBT:
    • Individual or group based
    • Group therapy is especially successful for veterans and survivors of natural disasters.
  • Eye movement desensitization and reprocessing (EMDR):
    • New therapy
    • The patient is told to focus on the lateral movement of the clinician’s finger while visualizing the traumatic experience.
    • The patient processes the trauma while in a state of relaxation/distraction.


  • Selective serotonin reuptake inhibitors (SSRIs): 1st-line therapy (e.g., sertraline, paroxetine) 
  • Selective norepinephrine reuptake inhibitors (SNRIs) (e.g., venlafaxine)
  • Atypical serotonergic agents (e.g., nefazodone) 
  • Alpha blockers (prazosin) shown to decrease nightmares and insomnia while also lowering severity of daytime symptoms 
  • Long-term use of benzodiazepines and antipsychotics not recommended in PTSD (benzodiazepines increase risk of drug dependence).

Related videos

Differential Diagnosis

  • Acute stress disorder: stress reactions that present after an individual has experienced a life-threatening event. Symptoms last more than 3 days and less than 1 month and involve re-experiencing the event as flashbacks or nightmares, avoiding reminders, irritability, hyperarousal, and poor memory and concentration. To qualify as acute stress, the traumatic event must have occurred within a month; for PTSD, it may happen at any point in the past. Symptoms last less than a month, unlike the longer duration in those with PTSD. 
  • Adjustment disorder: psychological response to identifiable stressor, marked by emotional or behavioral symptoms that develop < 3 months from exposure and lasting < 6 months. Adjustment disorder differentiates itself from PTSD by having a less defined set of symptoms and lack of reactive symptoms to trauma (e.g., intrusion, negative mood, dissociative symptoms, arousal symptoms). Treatment involves CBT and pharmacological adjuncts (SNRIs, SSRIs).
  • Brief psychotic disorder: presence of 1+ psychotic symptoms lasting 1+ day and < 1 month. Brief psychotic disorder usually has sudden onset and is often stress related. The presence of psychotic symptoms, such as delusions or hallucinations, distinguishes this diagnosis from acute stress disorder. Also, there is a full return to baseline functioning after an episode of brief psychotic disorder. Treatment involves 2nd-generation antipsychotics and psychotherapy. 
  • Panic disorder: chronic psychological disorder marked by recurrent and episodic panic attacks that occur abruptly and without a trigger. The episodes last from minutes to hours. Panic disorder is associated with anxiety or fear of having another attack or of its complications and some behavioral changes. Posttraumatic stress disorder can be distinguished by careful review of the onset of the anxiety and arousal symptoms. Intrusive symptoms, as well as negative mood changes associated with PTSD, are often not present in panic disorder.


  1. Sadock, BJ. Sadock, VA, & Ruiz, P. (2014). Kaplan and Sadock’s synopsis of psychiatry: Behavioral sciences/clinical psychiatry (11th ed.). Chapter 11, Trauma and stressor-related disorders, pages 437–446. Philadelphia, PA: Lippincott Williams and Wilkins.
  2. Nutt, DJ, & Malizia, AL. (2004). Structural and functional brain changes in posttraumatic stress disorder. The Journal of clinical psychiatry, 65 Suppl 1, pages 11–17.
  3. Mann, SK, Marwaha, R. Posttraumatic stress disorder. [Updated 2021 Feb. 20]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing.

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