A new study published in the Journal of the American Medical Association on Monday has answered the question, why some people are able to recover from a traumatic event, while others develop post-traumatic stress disorder (PTSD). The study has revealed that a gene that helps regulate the body's response to stress can make certain people more apt to develop post-traumatic stress disorder than others exposed to similar trauma.

According to the study by scientists at Emory University, PTSD, an anxiety disorder that can appear after a person experiences a terrifying event such as physical abuse, rape, military combat, war, torture, accidents and disasters, is much more likely to affect adults who experienced trauma in childhood, but variations of a certain gene raise the risk even more if the childhood trauma was related to physical or sexual abuse.

The authors of the study wrote, "Posttraumatic stress disorder (PTSD) is a debilitating stress-related psychiatric disorder, with prevalence rates of at least 7 percent to 8 percent in the U.S. population, and with much higher rates among combat veterans and those living in high-violence areas. Initially viewed as a potentially normative response to traumatic exposure, it became clear that not everyone experiencing trauma develops PTSD. Thus, a central question in research on PTSD is why some individuals are more likely than others to develop the disorder in the face of similar levels of trauma exposure."

Involving 900 adults mostly African-American aged from 18 to 81 and most of them had suffered severe traumatic experiences in childhood, followed by other kinds of trauma in adulthood, the study revealed that the adults who suffered severe abuse in childhood, those who showed gene variations had the post-traumatic stress level more than twice as high compared to the ones whose genes showed no variation. The study is one of the few to prove that genes can be influenced by outside factors.

The study concluded that severe abuse that happens very early in life can lead to profound traumas in adulthood, and the gene that controls stress hormones is called FKBP5 and the protein it produces helps cells receptors detect stress hormones.