Post-traumatic stress disorder (PTSD) is a mental health problem a person may develop after experiencing traumatic events. PTSD was first diagnosed in war veterans and was often called a shell shock. While some people have heard about this disorder, there are lots of misconceptions about PTSD. For example, people may wrongly assume it means the person is 'dwelling' on past events. They might even suggest that the person suffering should 'get over it' or 'move on.