Is PTSD being over-diagnosed?

NEW YORK - DECEMBER 15: Program facilitator Dan McSweeney gives a presentation about PTSD treatment December 15, 2009 at Fort Hamilton Army Garrison in Brooklyn, New York. The presentation and associated questionaire are part of the Military Pathways program, a free, anonymous mental health and alcohol self-assessment for troops, civilian employees, and their families. The self-assessments are a series of questions that help establish whether respondents could benefit from talking to an available health professional. PTSD and related mental health ailments have increased in recent years as hundreds of thousands of troops have served in the wars in Iraq and Afghanistan. (Photo by Chris Hondros/Getty Images)

After this month's shooting rampage at Fort Hood, we learned the alleged gunman, Specialist Ivan Lopez, was being assessed for post-traumatic stress disorder - despite having never seen combat during his four-month deployment to Iraq.

After this month's shooting rampage at Fort Hood, we learned the alleged gunman, Specialist Ivan Lopez, was being assessed for post-traumatic stress disorder - despite having never seen combat during his four-month deployment to Iraq.

The Pentagon says 155,000 U.S. troops have PTSD - and that's just a sliver of the 7.7 million Americans said to suffer from it. So what exactly is PTSD and how has its definition changed over the years we've learned more about it?

The latest DSM (Diagnostic and Statistical Manual of Mental Disorders) defines it as a psychiatric disorder that can occur in people who have experienced (directly or indirectly) or witnessed a traumatic event such as a natural disaster, a serious accident, a violent event such as war/combat, sexual assault or other violent personal assault.

In some studies, people who developed PTSD sometimes experienced events that were not necessarily as traumatic as rape and combat, such as non-life-threatening auto accidents. Whatever the cause, the common consequences are flashbacks, emotional avoidance and hyperarousal.

As we learn more about PTSD, will its diagnoses expand or be limited? Have you experienced PTSD? How have you communicated your diagnosis to people in your life?

Guest:

Dr. Richard J. McNally, Professor and Director of Clinical Training Harvard University’s Department of Psychology. He is a clinical psychologist, anxiety disorders and PTSD researcher, and the author of "What is Mental Illness?" and "Remembering Trauma."