Post Traumatic Stress Disorder is a response to a particularly threatening or catastrophic event, such as terrorism or natural disasters. It can come on any time from a few days after the event to a few months later.
There are usually flashbacks of the event, sleep disturbance and nightmares, anxiety, and the person tends to avoid anything that reminds them of the event. Anxiety and depression are common, as is increased alcohol or drug use.
If you are mainly concerned about psychological treatment, choose a product which offers cover for psychiatric treatment.