A traumatic event is much more likely to result in posttraumatic stress disorder (PTSD) in adults who experienced trauma in childhood - but certain gene variations raise the risk considerably if the childhood trauma involved physical or sexual abuse, scientists have found.
The research was conducted with funding from the National Institute of Mental Health, which is part of the National Institutes of Health, and others.
“Untangling complex interactions between genetic variations and environmental factors can help us learn how to predict more accurately who's at risk of disorders like PTSD. It can help us learn which prevention and treatment strategies are likely to work best for each person,” said NIMH Director Thomas R. Insel, M.D.
Results of the study were reported on March 18 in a special issue of the Journal of the American Medical Association devoted to the influence of genes on health and disease, by Elisabeth Binder, M.D., Ph.D., Kerry J. Ressler, M.D., Ph.D., and colleagues from Emory University and other facilities.
“These results are early and will need to be replicated, but they support the hypothesis that combinations of genes and environmental factors affect the risk for stress-related disorders like PTSD,” Ressler said. “Understanding how gene-environment interactions affect mental health can help us understand the neurobiology of these illnesses.”
The gene in question is active in the biochemical make-up of the body's stress-response system. Results of the study suggest that early-life abuse can result in particularly potent changes to this system as it develops – depending partly on whether or not the variations are present in the gene.
Inherited variations in multiple genes, which have yet to be identified, are estimated to account for 30 to 40 percent of the risk of developing PTSD. The gene identified in this study is one likely candidate, although others are almost certain to emerge.
To conduct their study, the researchers surveyed 900 primarily African-American people 18 to 81 years old, from poor, urban neighborhoods. As is common in impoverished environments, many of the people in this study had experienced severe traumatic experiences in childhood and had later experienced other kinds of trauma as adults. The researchers also examined the genetic make-up of 765 of the participants.