Witnessing or experiencing a traumatic event is the trigger that can cause PTSD in some people. Traumatic events that may trigger the development of PTSD in include:
- combat or military exposure
- childhood sexual or physical abuse
- physical or emotional abuse as an adult
- sexual assault or other violent crime
- terrorist attacks
- car accidents
- plane crashes
- natural disasters (e.g. fire, hurricane, earthquake)
- life-threatening illness
- death of loved one
While it is clear that these events can trigger PTSD, and witnessing or experiencing such an event is required to develop the disorder, this does not explain why some people who experience such events develop PTSD while others do not. Psychologists believe that several factors probably interact to cause the disorder. In addition to witnessing or experiencing a traumatic event, other factors that determine whether a person develops PTSD likely include genetic factors, previous life experiences, natural temperament and ability to cope with stress, and levels of chemical signals in the brain called neurotransmitters. Researchers are still trying to understand what role each of these factors plays in the development of PTSD.