Definition and Overview
Post-traumatic stress disorder (PTSD) is a mental health disorder in which four groups of symptoms - intrusion, avoidance, negative cognition/mood, and hyperarousal - persist for more than one month after exposure to a traumatic event that is life-threatening or causes extreme physical and psychological damage.
Approximately 70% of the world's population is exposed to a traumatic event at least once in their lifetime, and approximately 20% of these people develop PTSD. The lifetime prevalence is approximately 7-8%, and is approximately twice higher in women than in men. The higher prevalence among women is related to differences in rates of experiencing sexual violence and the effect of female hormones on memory processing.
Diagnostic criteria
A diagnosis of PTSD according to DSM-5 (Diagnostic and Statistical Manual of Mental Disorders, 5th edition) criteria includes:
Criterion A (Trauma Exposure): Experienced, witnessed, or learned of an actual or threatened death, serious injury, or sexual assault occurring to someone close to you.
Criterion B (Intrusive Symptoms): Recurrent involuntary re-experiencing of traumatic memories, trauma-related nightmares, dissociative reactions (flashbacks), and psychological and physiological distress in response to cues symbolic of the trauma.
Standard C (avoidance): Avoidance of memories, thoughts, and emotions related to the trauma; avoidance of external stimuli (places, people, conversations, activities) that remind of the trauma.
Criterion D (Negative changes in cognition and mood): Inability to remember important aspects of the trauma, persistent negative beliefs about self and the world, distorted self-blame, persistent negative emotional states, decreased interest in important activities, feelings of isolation, and limited positive emotions.
Criterion E (Hyperarousal): Irritability/outbursts of anger, reckless behavior, hyperarousal, exaggerated startle response, difficulty concentrating, sleep disturbance.
Symptoms must persist for more than 1 month.
Autonomic nervous system dysfunction
PTSD causes persistent changes in the autonomic nervous system, which is one of the core pathological mechanisms of PTSD.
Sympathetic hyperactivation is characteristic. At rest, heart rate and blood pressure increase, skin conductance response increases, and cortisol and norepinephrine secretion increase. Exposure to trauma-related stimuli triggers an excessive fight-or-flight response.
It is accompanied by a decrease in parasympathetic (vagus) nerve function. In heart rate variability (HRV) studies, PTSD patients consistently report a decrease in overall HRV, especially the high frequency (HF) component (vagal index), compared to normal controls. This is associated with a decline in the ability to control emotions.
Prolonged autonomic imbalance is associated with increased risk of cardiovascular disease, decreased immune function, metabolic abnormalities, and premature aging.
neurobiological mechanism
Hyperactivity of the amygdala is involved in excessive encoding and reactivation of fear memories. As the activity of the prefrontal cortex decreases, the inhibitory function of the amygdala decreases and emotional control becomes difficult. Reduced hippocampus volume is reported, which is associated with difficulties processing contextualized traumatic memories.
Cortisol response changes due to dysregulation of the HPA axis (hypothalamic-pituitary-adrenocortical axis). In PTSD, paradoxically, there is a tendency for basal cortisol to be low or circadian fluctuations to be blunted.
treatment
psychotherapy
Trauma-focused cognitive behavioral therapy (CBT) and eye movement desensitization and reprocessing (EMDR) are evidence-based first-line treatments. A Cochrane review found that both treatments showed significant reductions in PTSD symptoms, and trauma-focused CBT and EMDR were reported to be equivalent in efficacy.
Cognitive processing therapy (CPT) and prolonged exposure therapy (PE) are also widely used evidence-based treatments.
medication
SSRIs (sertraline, paroxetine) and SNRIs (venlafaxine) are FDA-approved or evidence-based first-line drugs. Prazosin is effective for nightmares and sleep disorders. Propranolol may be used for severe hyperarousal.
Neuromodulation treatment
The results of a randomized controlled trial have reported that stellate ganglion block is effective in controlling sympathetic nerve hyperactivity in PTSD. Transcranial magnetic stimulation (TMS), especially rTMS, is also being studied for reducing PTSD symptoms.