What Causes Posttraumatic Stress Disorder?

When people live through a trauma, the memories of what happened get connected in their minds with what they saw, heard, smelled, or felt at the time. Later a similar sight, sound, smell, or other feeling can bring the memories and emotions flooding back. A second reason why the memories come back is that people have a need to make sense of what happened. Traumatic events often make people question things they once believed-for example, that the world is basically safe or that bad things won’t happen to them. To understand the trauma, they have to think about it. But thinking about it brings the memories and feelings back. So they try not to think about it. Instead of finding understanding and peace, people often end up going back and forth between remembering and trying to forget