National Institute of Mental Health: U.S. Department of Health and Human Services: National Institutes of Health.
This is a free pamphlet available from NIMH which you can order through the internet. If gives a very good description of what is PTSD using the criteria set for in DSM. PTSD is an anxiety condition which manifests after someone has experienced a dangerous event, either personally or through others who are close. The diagnosis requires one re-experiencing symptoms such as flashback, bad dreams or frightening thoughts; three avoidance symptoms such as, staying away from places, event, objects which remind you of the event, feeling numb, feeling guilt, depression or worry, losing interest in activities that were previously enjoyable and having trouble remembering things about the event; and two hyper-arousal symptoms such as being easily startled, feeling tense or on edge or having difficulty sleeping or having angry outbursts. While it is normal to have some effect from living through a dangerous event, PTSD symptoms have usually lasted for more than a month. In young children symptoms may include a regression in learned behavior—such as wetting the bed when they did not before, forgetting or not being able to talk, acting out the scary event in play or being unusually clingy.
There are risk factors for PTS as well as resilience factors. Risk issues include getting hurt, living through a dangerous event, history of mental illness, seeing people hurt or killed, feeling horror, helpless or extreme fear, having little social contact, having extra stress. Resilience factors include seeking support from other people, finding a support group, feeling good about your own actions, being able to respond effectively despite fear.
PTSD can respond well to talk therapies. Cognitive Behavioral therapy, with cognitive restructuring, stress inoculation and exposure therapies can help. In some cases medications can help with feeling of hopelessness. Zoloft and Paxil have been approved, but need to be taken with care as they have been shown to increase the risk of suicide, especially in young people.
Mass trauma (such as an earth quake or large event) is a special incident where many people have been traumatized at the same time. Psychological debriefing, where you talk with a group of people, has not been proven to be effective. However helping people regain some control over their lives is helpful. Efforts should include: getting to a safe place, seeing a doctor if injured, getting food and water, contacting loved ones and leaning what is being done to help. In this instance, educational support can be beneficial.
Another aspect of mass trauma, is that the helping community will also be traumatized. Special care should be taken so those helping do not break down from the stress.