Post Traumatic Stress Disorder (PTSD) consists of a constellation of symptoms in response to a life threatening event that includes avoidance of reminders of the trauma, emotional numbing, and emotional withdrawal from other people. Reminders of the trauma, which may be people, places, or events, cause the person suffering from PTSD to become distressed, often similarly to their feelings at the time of the original trauma. The trauma often leaves people emotionally numbed, meaning that they have difficulty feeling common human emotions like joy and happiness. The trauma itself often leaves the person who has suffered the trauma separate and apart from other people because other people have not experienced anything like their trauma, and consequently other people cannot understand them. Interestingly, PTSD is one of only two diagnoses in our current schema that require a preceding event (the other is Reactive Attachment Disorder).