CHICAGO - Genes could help explain why some people recover from a traumatic event while others suffer post-traumatic stress disorder, researchers say.
Though preliminary, a recent study provides insight into a condition expected to strike servicemen and women returning from Iraq and Afghanistan, a health specialist said.
Researchers found that specific variations in a stress-related gene appeared to be influenced by trauma at a young age - in this case child abuse. That interaction strongly increased the chances for adult survivors of abuse to develop signs of PTSD.
Among adult survivors of severe child abuse, those with the specific gene variations had more than twice as high a score (31) on a scale of post-traumatic stress, compared with those without the variations (13).
The worse the abuse, the stronger the risk in people with those gene variations.
The study of 900 adults is among the first to show that genes can be influenced by outside, nongenetic factors to trigger signs of PTSD. It is the larger of two reports to show molecular evidence of a genetic influence on PTSD.
"We have known for over a decade, from twin studies, that genetic factors play a role in vulnerability to developing PTSD but have had little success in identifying specific genetic variants that increase risk," said Karestan Koenen, a Harvard psychologist doing similar research. She was not involved in the new study.
The results suggest that there are critical periods in childhood when the brain is vulnerable "to outside influences that can shape the developing stress-response system," said study coauthor Dr. Kerry Ressler of Emory University.
The study appears in today's Journal of the American Medical Association.