PTSD Causes: Causes of Posttraumatic Stress Disorder

Causes of post-traumatic stress disorder (PTSD) are not fully understood. Genetics and personal life events may contribute to PTSD causes.

The causes of post-traumatic stress disorder (PTSD) are not well known or understood. Posttraumatic stress disorder is an anxiety disorder that occurs after being involved in a traumatic event involving harm, or threats of harm to the self or others. Even learning about an event has the possibility of causing PTSD in some people.

Prior to the third edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM) in 1980, PTSD was not recognized, and those who exhibited the symptoms were considered to be having an exaggerated stress reaction (Is PTSD a Mental Illness? PTSD in the DSM-5). This reaction was attributed to a character flaw or personal weakness. We now know that character does not cause PTSD and there are physical, genetic and other causes of PTSD at work. 

While one could think of the trauma as the cause of PTSD, some people can undergo trauma and not develop posttraumatic stress disorder. Posttraumatic stress disorder is initiated by trauma, but the causes of PTSD are related to the brain and risk factors for developing an anxiety disorder. (Even though the complete cause of PTSD is not known, PTSD help and effective PTSD treatments are available.)

The events most likely to cause post-traumatic stress disorder (PTSD) are:1

However, any kind of event perceived as traumatic can trigger PTSD (Do I Have PTSD? PTSD Test).

Physical Causes of Posttraumatic Stress Disorder (PTSD)

Brain structures and brain chemicals have both been implicated in the causes of PTSD. Research shows that exposure to trauma can cause "fear conditioning" of the brain. Fear conditioning is where the person learns to predict traumas and the predicted traumas cause parts of the brain to activate. With posttraumatic stress disorder, fear conditioning causes the brain to anticipate danger where none exists, causing PTSD symptoms.2

Additionally, the parts of the brain that are designed to dampen this fear response seem less capable of doing so in those with PTSD. This may be caused by stress-induced atrophy of the brain structures in that area.

PTSD Causes: Risk Factors for PTSD

It's possible for two people to go through the same trauma and only one will develop PTSD, indicating that some people carry additional risk factors for posttraumatic stress disorder. Genetics is thought to pass down some of the physiological vulnerability that leads to the causes of PTSD.

Personal characteristics are also known to increase the risk for PTSD. Characteristics that can contribute to posttraumatic stress disorder (PTSD) causes include:

  • Exposure to previous traumas, particularly as a child
  • Childhood adversity
  • Preexisting conditions like anxiety or depression
  • Family history of anxiety or depressive disorders
  • Gender (more women than men develop PTSD)

Some of the causes of PTSD are thought to be related to the type of trauma itself. Exposures that are more likely to cause PTSD are:

  • More severe
  • Longer in duration
  • Closer to the individual

Some factors can predict a better outcome for PTSD (Does A PTSD Cure Exist?). These predictive factors include:

  • Availability of social support
  • Lack of avoidance or emotional numbing symptoms
  • Lack of hyperarousal (also known as the fight-or-flight response) symptoms
  • Lack of symptoms related to re-experiencing the trauma

article references

APA Reference
Tracy, N. (2021, December 17). PTSD Causes: Causes of Posttraumatic Stress Disorder, HealthyPlace. Retrieved on 2024, July 23 from

Last Updated: February 1, 2022

Medically reviewed by Harry Croft, MD

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