Traumatic experiences can cause significant pyschological problems for large numbers of people. Not everyone is affected but it is estimated that 13% of people involved in car crashes and 19% of people who are victims of violent crime go on to suffer from acute stress disorder. Rates of acute post-traumatic stress disorder (PTSD), which is defined as PTSD symptoms for less than three months, vary from 23% of those involved in car crashes to 47% in rape victims. A third of people who develop acute PTSD go on to develop chronic PTSD, suffering symptoms for 6 years or longer. People have tried to develop interventions to prevent the development of chronic PTSD. One such intervention was psychological debriefing but this began to be questioned in the 1990s, little evidence was found for its effectiveness and many experts now advise against it. A review of 25 studies by researchers at Cardiff University found that trauma-focused cognitive-behaviour therapy (CBT) was more effective than doing nothing or supportive counselling for acute stress disorder and acute PTSD.
Roberts, Neil P. ... [et al] - Systematic review and meta-analysis of multiple-session early interventions following traumatic events American Journal of Psychiatry March 2009, 166(3), 293-301