This information is extracted from the website of Australian Centre for Posttraumatic Mental Health website.
PTSD is a set of reactions that can develop in people who have experienced or witnessed an event which threatened their life or safety, or that of others around them, and led to feelings of intense fear, helplessness or horror. It could be a car or other serious accident, physical or sexual assault, war or torture, or natural disasters such as bushfires or floods. Other life changing situations such as being retrenched, getting divorced or the expected death of an ill family member, are very distressing and may cause serious mental health problems, but are not events that can cause PTSD.
Anyone can develop PTSD following a traumatic event but people are at greater risk if the event involved physical or sexual assault, they have had repeated traumatic experiences such as sexual abuse or living in a war zone, or they have suffered from PTSD in the past.