PTSD causes

Post-traumatic stress disorder is an extreme reaction to extreme stress. In moments of crisis, people respond in ways that allow them to endure and survive the trauma. Afterward those responses, such as emotional numbing, may persist even though they are no longer necessary.

Not everyone who experiences a traumatic event develops post-traumatic stress disorder. Several factors influence whether people develop the disorder. Those who experience severe and prolonged trauma are more likely to develop the disorder than people who experience less severe trauma. Additionally, those who directly witness or experience death, injury, or attack are more likely to develop symptoms.

People may also have existing biological and psychological vulnerabilities that make them more likely to develop the disorder. Those with histories of anxiety disorders in their families may have inherited a genetic predisposition to react more severely to stress and trauma than other people. In addition, people's life experiences, especially in childhood, can affect their psychological vulnerability to the disorder. For example, people whose early childhood experiences made them feel that events are unpredictable and uncontrollable have a greater likelihood than others of developing the disorder. Individuals with a strong, supportive social network of friends and family members seem somewhat protected from developing post-traumatic stress disorder.