Department of Psychiatry
Penn Behavioral Health

Center for the Treatment and Study of Anxiety

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Post-traumatic Stress Disorder


Posttraumatic Stress Disorder (PTSD) is a pathological anxiety disorder resulting after exposure to a traumatic event. Current literature estimates that 8% of the U.S. population meets the criteria for PTSD and while PTSD cases commonly involve combat or assault experiences, there is a wide range of events capable of triggering PTSD symptoms. These events include car accidents, kidnappings, terrorist attacks, natural disasters, and any other traumatic experience where an individual experienced or witnessed an event that involved death or the threat of physical harm.

For example, should a car accident occur, PTSD could result in the drivers, the passengers, or a witness; yet, the development of PTSD in one individual does not imply the development of PTSD in others involved in the incident. How one responds to an event is dependent on a variety of factors that lie outside the traumatic experience itself.

Common Symptoms

PTSD is characterized by 4 primary symptoms:

  • Intrusion: Recurrent recollections of the event
    • Dreams, intrusive memories, and exaggerated emotional and physical reactions to events that remind person of trauma
  • Numbing: Emotional distancing from surrounding people and events
    • Depression, loss of interest in activities, reduced ability to feel emotions (particularly emotions of intimacy, tenderness, or sexuality), irritability, hopelessness
  • Avoidance: Fear and avoidance behavior
    • Fear and avoidance of people, places, thoughts, or activities associated with the trauma, development of anxiety disorders (GAD, panic, specific and social phobias)
  • Arousal: Agitated state of constant wakefulness and alertness
    • Hypervigilance, sleep disturbances, difficulty concentrating

Take, for example, somebody who witnesses a major car accident on a highway by their home. Over the following week, the individual begins to avoid driving on that highway and over the next month, avoids driving all together - either as a driver or a passenger. He/she may become irritable or angry while watching high-speed car chase scenes or avoid conversations about driving; yet, despite the apparent discomfort, the individual may refuse to discuss his/her fear. Moreover, although the witness is unwilling to discuss the fear or the traumatic event itself, he/she may still be haunted by the memory of the accident with segments of the event on “constant replay” in his/her mind.

Young children do not experience the same reliving of the experience as adults. The progression of PTSD in young children may initially involve dreams about the traumatic event, however, these dreams frequently transform into more generalized nightmares about monsters or different threatening situations where they or another person is in danger. It is more difficult for children to express their sentiments verbally. Therefore, it is necessary for parents or teachers or other adult observers to recognize behavioral changes such as a decreased interest in activity or an altered sense of the future (i.e. the child now believing that he/she will no longer live to become an adult). Other signs of childhood PTSD may occur in the form of repetitive play if the child begins to recreate the incident with toys or may occur through the emergence of physical symptoms such as headaches or stomach aches.

Less Common Symptoms

An individual’s PTSD might include additional symptoms, such as feelings of shame, or less commonly, compulsive or aggressive behaviors, or self-destructive behavior. These cases often interfere with an individual’s personal life and thus, they are also associated with certain social patterns. These patterns may include sexual dysfunction, marital conflicts, and job loss. There are also strong feelings of guilt and despair that lead to social withdrawal and substance abuse.

Rare cases of PTSD may involve auditory hallucinations and paranoid ideation. Individuals who experience auditory hallucinations may experience tinnitus, a constant ringing in one’s ears, or they may hear a voice or set of voices that are not physically present. Individuals who are experiencing paranoid ideation are highly guarded and constantly suspicious of being harmed and harassed by those around them.

Recently, researchers have begun to distinguish PTSD from a more severe form of the disorder, Complex PTSD (C-PTSD). The new diagnosis is considered necessary in describing cases that result from prolonged, repeated trauma. C-PTSD is recognized by the following indications:

  • Severe behavioral difficulties (substance abuse, aggression, eating disorders)
  • Difficulty controlling intense emotions (extreme anger outbursts, panic, depression)
  • Significant mental difficulties (amnesia, dissociative symptoms)

Onset & Course

The development of PTSD is somewhat unpredictable and can occur at any age. The severity and timing of PTSD symptoms differ with each individual. Cases are thus categorized according to the following classifications:

  • Acute: symptoms present less than three months
  • Chronic: symptoms present three months or longer
  • With Delayed Onset: symptoms develop at least six months after the event

PTSD typically develops immediately after the trauma. Nonetheless, in some cases symptoms may not emerge until years have passed since the event. Additionally, a traumatic incident may cause mild PTSD symptoms in one individual while chronically debilitating another. People tend to recover from trauma naturally over time, but as a rule of thumb, symptoms lasting a year or more do not remit without treatment.

All PTSD sufferers usually experience a range of symptoms after a traumatic episode. These symptoms are maintained through avoidance behavior and treatment must be actively pursued in order for complete recovery. Particular variables surrounding the traumatic event may, however, influence the development of PTSD. Elements that are known to make PTSD more likely are the following:

    • Uncontrollable, unexpected, or inescapable events
    • Degree of threat, suffering, or fear
    • Human-caused, rather than natural, event
    • Assault, often with a sense of betrayal
    • Sense of responsibility
    • Past and present vulnerability, including genetics, childhood trauma, insufficient emotional support, concurrent causes of stress

Example: Childhood abuse and rape

Symptoms of PTSD may emerge later in life. Example: “When I was child, I was abused by my uncle. I was scared by it at first but I eventually came to accept it. He stopped when I was twelve (I have not seen him since). I tried to forget him and blocked the memory from my mind. I had a healthy romantic life throughout high school and college. I dated numerous people and have been involved in two serious relationships. Last year, however, my best friend was raped by a co-worker. I consoled her and she recovered from the experience but since then, I have not been able to stop thinking about my uncle..."



What causes PTSD?

Why one person gets PTSD and not another is not completely understood. However, a traumatic experience is required for a diagnosis. Trauma events frequently associated with the development of PTSD include the following:

    • Physical, emotional, or sexual abuse
    • Combat experiences
    • Terrorist attacks
    • Natural disasters such as tornados, floods, earthquakes, or fires
    • Life-threatening accidents, such as automobile accidents, airplane crashes, or boating accidents both experienced or witnessed
    • Violent crimes, both experienced or witnessed

Epidemiological information

The prevalence of PTSD differs according to both gender and ethnicity. An estimated 8% of the U.S. adult population matches the criteria for PTSD with women more likely to develop symptoms than men. Within the U.S., there is evidence that African-Americans, Hawaiin-Americans, Native Americans and Latino-Americans develop more severe forms of PTSD than European-Americans. Research also suggests that Asian-Americans have the lowest rates of PTSD within the country. These differences are attributed to a variety of cultural and socioeconomic phenomena.

Globally, Iceland and Australia are credited with the lowest prevalence of PTSD. Iceland has a rate of 0.6% and Australia, a slightly higher rate of 1.5%. This follows the general finding that developed countries have significantly lower rates of PTSD than the developing world. The prevalence of PTSD in the developing world is, however, reasonable given the harsher political and economic climates.


More Information

National Institute of Mental Health (NIMH) - An organization with the National Institute of health dedicated to mental health research:

Army Behavioral Health - A PTSD informational website provided by the U.S. Army Medical Department for the support of Soldiers and their families:

National Center for PTSD (NCPTSD) - A center established by the U.S. Department of Veteran Affairs to improve the well-being of U.S. veterans through PTSD research and education:

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