Definition and Overview
Post-traumatic stress disorder (PTSD) is a mental health disorder that develops after exposure to a traumatic event that threatens life or causes extreme physical and psychological harm, characterized by four symptom clusters -- intrusion, avoidance, negative alterations in cognition and mood, and hyperarousal -- persisting for more than one month [1].
Approximately 70% of the global population is exposed to at least one traumatic event in their lifetime, and approximately 20% of those develop PTSD [2]. The lifetime prevalence is approximately 7–8%, and it is approximately twice as high in women compared to men [2]. The higher prevalence in women is related to differences in sexual violence victimization rates and the influence of female hormones on memory processing.
Diagnostic Criteria
PTSD diagnosis according to DSM-5 (Diagnostic and Statistical Manual of Mental Disorders, 5th Edition) criteria includes the following [1].
Criterion A (Trauma exposure): Direct experience, witnessing, or learning about actual or threatened death, serious injury, or sexual violence occurring to a close person.
Criterion B (Intrusion symptoms): Recurrent involuntary re-experiencing of traumatic memories, trauma-related nightmares, dissociative reactions (flashbacks), and psychological or physiological distress to cues symbolizing the trauma.
Criterion C (Avoidance): Avoidance of memories, thoughts, and feelings related to the trauma; avoidance of external reminders (places, people, conversations, activities) of the trauma.
Criterion D (Negative alterations in cognition and mood): Inability to remember key aspects of the trauma, persistent negative beliefs about oneself and the world, distorted blame, persistent negative emotional states, diminished interest in significant activities, feelings of detachment, and restricted positive emotions.
Criterion E (Hyperarousal): Irritability/anger outbursts, reckless behavior, hypervigilance, exaggerated startle response, difficulty concentrating, and sleep disturbances.
Symptoms must persist for more than one month [1].
Autonomic Nervous System Dysfunction
PTSD produces persistent changes in the autonomic nervous system, which represents one of the core pathological mechanisms of the disorder.
Sympathetic hyperactivation is characteristic. Elevated resting heart rate and blood pressure, increased skin conductance response, and increased cortisol and norepinephrine secretion are observed. Exposure to trauma-related stimuli triggers an exaggerated sympathetic fight-or-flight response.
Parasympathetic (vagal) hypofunction is concomitant. HRV studies consistently report that PTSD patients show overall reduced HRV compared to healthy controls, particularly decreased high-frequency (HF) component (a vagal tone marker) [3]. This is associated with impaired emotional regulation.
When this autonomic imbalance becomes chronic, it is associated with increased cardiovascular disease risk, immune dysfunction, metabolic abnormalities, and premature aging [5].
Neurobiological Mechanisms
Amygdala hyperactivation is involved in excessive encoding and reactivation of fear memories. Reduced prefrontal cortex activity diminishes amygdala inhibition and impairs emotional regulation. Hippocampal volume reduction has been reported, which is related to difficulty processing contextualized traumatic memories.
HPA axis (hypothalamic-pituitary-adrenal axis) dysregulation alters cortisol responses. Paradoxically, PTSD is associated with lower baseline cortisol levels or blunted diurnal cortisol variation.
Treatment
Psychotherapy
Trauma-focused cognitive behavioral therapy (trauma-focused CBT) and eye movement desensitization and reprocessing (EMDR) are evidence-based first-line treatments [4]. Cochrane reviews demonstrate that both treatments produce significant reductions in PTSD symptoms, with trauma-focused CBT and EMDR showing equivalent efficacy [4].
Cognitive processing therapy (CPT) and prolonged exposure therapy (PE) are also widely used evidence-based treatments.
Pharmacological Treatment
SSRIs (sertraline, paroxetine) and SNRIs (venlafaxine) are FDA-approved or evidence-based first-line medications [3]. Prazosin is effective for nightmares and sleep disturbances [3]. Propranolol may be used for severe hyperarousal.
Neuromodulation Therapy
Randomized controlled trial results have reported that stellate ganglion block is effective for modulating sympathetic hyperactivation in PTSD. Research on transcranial magnetic stimulation (TMS), particularly rTMS, for PTSD symptom reduction is ongoing.