PTSD develops in 20–25% of people who have exposed to or witnessed an event that involves a direct threat to one's life or physical/psychological integrity.Time limited responses develop in 50–70% of victims during the first 48–72 hours and in 30–40% over the first 4 weeks.

Many of those with acute post-traumatic symptoms will eventually recover.However,30–40% of those with ASD,will develop PTSD.It thus appears that some people are more vulnerable than others to the pathogenic effects of trauma while others have neurobiological resources that make them resilient to the long term impact of traumatic exposure.

In this study various aspects of vulnerability to PTSD will be discussed with a focus on predicyion and early identification of subjects at risk that should be the target for early therapeutic intervention.After a general overview by author,will discuss the impact of physical injury on the risk for PTSD and present data showing increased vulnerability to PTSD in trauma victims with body injuries,and will present data on the impact of memory for the trauma on the vulnerability to PTSD.