March 31, 2008

Gene Variations Affect PTSD Risk for Adults Abused as Children

Photo of an African-American man comforting an African-American woman

Certain gene variations, a new study has found, make adults who were abused as children more likely to develop posttraumatic stress disorder (PTSD) after a traumatic event.

Researchers have known that adults who experienced trauma in childhood are more likely to develop PTSD after a traumatic event later in life. But scientists believe there’s also a genetic component to the disorder. Some people are more likely than others to develop PTSD after being exposed to similar levels of trauma. Inherited genetic variations are estimated to account for 30-40% of the risk of developing PTSD, although the genes involved haven’t yet been identified.

A research team headed by Dr. Elisabeth Binder and Dr. Kerry J. Ressler of Emory University set out to explore the interaction between environmental and genetic influences on the development of PTSD. The researchers surveyed 900 people from poor, urban neighborhoods. The participants were between 18 and 81 years old and were primarily African-American. Many had severe traumatic experiences in childhood and later other kinds of traumatic incidents as adults.

The researchers also examined 765 of the participants for variations in a gene called FKBP5, which plays a role in regulating the response to stress. Their work was supported primarily by NIH’s National Institute of Mental Health (NIMH), with additional funding from NIH’s National Institute on Drug Abuse (NIDA), National Center for Research Resources (NCRR) and others.

The results appeared in the March 19, 2008, issue of the Journal of the American Medical Association. The researchers found that adults with a history of child abuse—almost 30% of the people in the study—developed more than twice the number of PTSD symptoms when they underwent later traumas as those who weren't abused in childhood.

Among the participants who weren’t abused in childhood, the researchers found no links between FKBP5 and the likelihood of developing PTSD.  However, for those with a history of child abuse, 4 FKBP5 variations affected the likelihood that they would develop PTSD after a later trauma.

These findings suggest that, for people with certain genetic variants, early-life abuse can result in potent changes to the stress response system as it develops. “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.

“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,” said NIMH Director Dr. Thomas R. Insel. “It can help us learn which prevention and treatment strategies are likely to work best for each person.”

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