Individuals who experience both childhood adversity and traumatic events in adulthood appear more likely to develop post-traumatic stress disorder than those exposed to only one of these types of incidents, according to a report in the November issue of Archives of General Psychiatry, one of the JAMA/Archives journals. In addition, the risk was further increased in individuals with a certain genetic mutation.
Although 40 percent to 70 percent of Americans have experienced traumatic events, only about 8 percent develop PTSD during their lifetimes, according to background information in the article. PTSD is a complex anxiety disorder that involves re-experiencing, avoidance and increased arousal following exposure to a life-threatening event. "In addition to the obvious effect of environmental factors, PTSD has a heritable component," the authors write. Recent studies estimate that genetic factors account for approximately 30 percent of the difference in PTSD symptoms.
Pingxing Xie, B.S., of Yale University School of Medicine, New Haven, Conn., and VA Connecticut Healthcare Center, West Haven, and colleagues studied 1,252 individuals who had experienced childhood adversity (including abuse or neglect), adult trauma (such as combat, sexual assault or a natural disaster) or both. Participants age 17 to 79 (average age 38.9) were interviewed and assessed for a variety of psychiatric and substance use disorders. DNA was extracted and used to differentiate between versions of a particular polymorphism or gene mutation—known as the 5-HTTLPR genotype—previously found to be associated with emotional response after stressful life events.
About one-fifth of the participants (229, or 18.3 percent) met criteria for PTSD. A total of 552 of the 1,252 participants (44.1 percent) experienced both childhood adversity and traumatic events in adulthood. These individuals were more likely to have a lifetime diagnosis of PTSD than were those who experienced trauma in only one life stage (29 percent vs. 9.9 percent).