Posttraumatic Stress Disorder (PTSD)

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Causes

It may be that, when combined, the person's psychological history, the nature of the trauma, and the availability of posttrauma support cause PTSD symptoms to develop after a traumatic event. However, someone without risk factors who is exposed to a traumatic event also may develop symptoms.

Biologic Theories
The amygdala, a structure in the brain, is part of the limbic system that is involved in the expression of emotion, especially fear, autonomic reactions (e.g., increased heart rate and blood pressure, the startle response), and emotional memory. Dysfunction in this structure may produce symptoms of PTSD.

Overwhelming trauma can cause changes in brain function that produce symptoms of PTSD: hyperarousal, numbing, sleep disturbance, irritability, intrusive emotions and memories, flashbacks, outbursts, and memory impairment.

The body responds to stress and trauma by releasing several stress hormones (e.g., norepinephrine, epinephrine). When a person is subjected to repeated or severe trauma, the physiological stress response becomes hyperactive and hyperarousal and intrusive symptoms of PTSD develop.

There also may be a biological component to numbing and other dissociative symptoms of PTSD. Some studies show that when people who have been exposed to prolonged or repeated trauma are exposed to any stimulus reminiscent of the trauma, the brain releases opiates (e.g., endorphins, enkephalins) that can produce emotional nonresponsiveness, or numbing, and amnesia.

Serotonin depletion may result from repeated exposure to severe stress and trauma, which may be a factor in the development of irritability and violent or angry outbursts in people with PTSD.

Risk Factors

Risk factors for PTSD include previous trauma; a predisposing mental health condition; the type and severity of the traumatic event; and lack of adequate and competent support for the person after the trauma. However, PTSD can develop in people who do not possess any of these risk factors.

Pretrauma Risk Factors
The psychological history of a person may include risk factors for developing PTSD after a traumatic event:

• Borderline personality and dependent personality disorders
• Low self-esteem
• Previous trauma

People with borderline personality disorder often have a history of physical and/or sexual abuse, neglect, hostile conflict, and parental loss or separation. Dependent personality disorder is characterized by low self-esteem, fear of separation, and the excessive need to be cared for by others. All of these features may predispose someone for PTSD who experiences a traumatic event.

People who have experienced previous trauma(s) are at risk for developing PTSD. Repeated exposure to trauma causes hyperactive release of stress hormones, which may be instrumental in creating symptoms of PTSD.

Trauma-Related Risk Factors
The severity, duration, proximity to (direct or witnessed), and type of traumatic event are the most significant risk factors for developing PTSD.

Directly experienced traumatic events include the following examples:

• Combat
• Kidnapping
• Natural disasters (e.g., fire, tornado, earthquake)
• Catastrophic accident (e.g., auto, airplane, mining)
• Violent sexual assault
• Violent physical assault

Witnessed traumatic events include the following examples:

• Seeing another person violently killed or injured
• Unexpectedly seeing a dead body or body parts

Whether or not the event was perpetrated in a sadistic manner (e.g., torture, rape) occurred accidentally (e.g., fire), or occurred as an "act of God" can affect whether a person develops PTSD and whether the disorder is acute, chronic, or has a delayed onset of symptoms.

Posttrauma Risk Factors
Symptoms and duration of PTSD may be more severe if there is a lack of support from family and/or community. For instance, a rape victim who either is blamed for the assault or not believed (e.g., in the case of rape by a family member) may be at greater risk for developing PTSD.

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