Post Traumatic Stress Disorder or PTSD is a condition that occurs mostly in people with existing anxiety disorders. It can occur after a traumatizing event such as the loss of a child or loved one, rape, robbery, or car accident. It has been also seen in war survivors.
The best way of how to help someone with PTSD is to be there for her or him for support. If the individual needs to talk about the pain it will be nice to to know that he or she has a friend who is willing to lend an ear. If the sufferer asks for information on professional help, direct him or her to nearest psychologist. More info: how to help someone with ptsd