A new study has suggested that people who have been abused as kids and who have variations of a gene, FKBP5, related to stress response may be at an increased risk of suffering from posttraumatic stress disorder (PTSD) symptoms as adults.
Researchers led by Dr Rebekah G. Bradley conducted the study in a sample of highly traumatized, low-income men and women living in an urban area. The research appears in the March 19 issue of JAMA, a theme issue on Genetics and Genomic.
The researchers tried to determine the role of variations (polymorphisms) in FKBP5 in predicting PTSD symptoms, and whether these genetic variations interact with increasing levels of both child abuse and other types of trauma exposure to be a predictor of PTSD symptoms during adulthood.
"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," wrote the authors.
They also added that it is becoming clear that there are critical roles for pre-disposing genetic and environmental influences in determining the psychological risk to the traumatized individual, with child abuse appearing to provide significant risk for the development of PTSD.
The study involved an examination of genetic and psychological risk factors in 900 general medical clinic patients with significant levels of childhood abuse as well as other types of trauma, using a survey combined with genetic testing (single-nucleotide polymorphism [SNP] genotyping).
The participants were largely urban, low-income, black men and women looking for care in the general medical care and obstetrics-gynaecology clinics of an urban public hospital, between 2005 and 2007.
It was found that both the level of child abuse and level of other types of trauma each separately predicted level of adult PTSD symptomatology.
Though genetic variations (FKBP5 SNPs) did not directly foretell PTSD symptom outcome or interact with level of non-child abuse trauma to predict PTSD symptom severity, four variations (SNPs) in the FKBP5 locus (the specific site of a particular gene on its chromosome) significantly interacted with the severity of child abuse to predict level of adult PTSD symptoms.
However, this gene-environment interaction was not considered significant enough while controlling for depression severity scores, age, sex, levels of trauma exposure other than child abuse and genetic ancestry.
"The most novel and important finding of our study was the interaction between FKBP5 polymorphisms and child abuse history to predict the levels of adult PTSD symptoms. These genotypes potentially serve as predictors of both risk and resilience for adult PTSD among survivors of child physical and sexual abuse," said the authors.
The findings of this study were presented at a JAMA media briefing at the National Press Club in Washington, D.C.