**3.1 Prevalence**

In the general population of the United States, posttraumatic stress disorder has been found to have a lifetime prevalence of 6.8 percent (Kessler et. al., 2005). Posttraumatic stress disorder is frequently seen in military personnel due to their elevated potential for exposure to trauma during combat. In the current war in Iraq and Afghanistan, the prevalence of posttraumatic stress disorder in soldiers post-deployment is believed to be between 10.3% and 17% (Sundin et. al., 2009). The prevalence of posttraumatic stress disorder for Vietnam Veterans ranges from 8.5% to 19.3% and between 1.9% and 24% for soldiers in the Persian Gulf War (Sundin et. al., 2009). Prevalence figures vary widely in the military based upon a number of variables, such as how posttraumatic stress disorder was assessed, how much time has elapsed since the trauma, the level of combat exposure, the number of completed tours, gender, and the unit the individual was assigned to during deployment.
