I'm a veteran without PTSD. I used to think something was wrong with me.

Many people wrongly assume that PTSD is inevitable for anyone exposed to trauma. Because I endured trauma at home and on the front lines but never suffered from PTSD, three years ago I volunteered to serve as a control for a study funded by the National Institute of Mental Health and the National Center for PTSD at the Department of Veterans Affairs. It is common to have flashbacks, nightmares and other symptoms after a traumatic event, but most people recover. This acute stress response is different from PTSD, which is diagnosed only when symptoms linger beyond 30 days and which requires more than time for recovery, with treatment typically consisting of either psychotherapy or medications or both. Although about 60 percent of the general public have experienced one or more traumatic events, only around 8 percent suffer from PTSD at some point in their lives. For veterans deployed to Iraq or Afghanistan the rate of PTSD is higher, ranging from 11 to 20 percent.

Now that I’m in medical school, I’ve learned there are a number of resiliency factors that might help protect people from developing PTSD. I happen to have a few of them: absence of childhood trauma, the choice to pursue more education and having close friends and family for social support. The study that I volunteered for would use brain-imaging technology to try to get an in-depth look at the neurobiology of PTSD, tracing the way fear and safety responses work in people with PTSD and in others who seemed to be resistant to the condition. If scientists can pinpoint particular brain activities or processes at work in people who’ve had an easier time processing traumatic events and memories, they might be able to develop better treatments for those who do develop the symptoms of PTSD.