Why some people get PTSD and others don't

It is thought that between 40-70% of Americans have experienced traumatic events yet only about 8% go on to develop post-traumatic stress disorder (PTSD) over the course of their lifetimes. Researchers from Yale University studied 1,252 people aged from 17 to 79 who had experienced adversity in their childhood and/or as an adult. People who had experienced adverse events in both adulthood and childhood were much more likely (29%) to develop PTSD than people who had 'only' experienced adversity in one part of their life (9.9%). A gene called 5-HTTLPR was also found to influence whether people developed PTSD or not but it was only found to increase in people who had had a double dose (in childhood and as an adult) of trauma.

You can find out more about this research at

http://www.sciencedaily.com/releases/2009/11/091102171409.htm