How many veterans in the U.S. have post-traumatic stress disorder?

The tracking of cases of post-traumatic stress disorder (PTSD) is usually done by specific conflict. For example, it is known that more than half of all Vietnam veterans (approximately 1.7 million) have had some PTSD symptoms. Studies of Persian Gulf veterans’ mental health estimated anywhere from 9% to 24% as suffering from PTSD. Thus far, in the ongoing conflicts in Iraq and Afghanistan, it is believed that about 12.5% of soldiers have had PTSD after deployment. Bear in mind that many cases of PTSD go unreported.