Low posttrauma GABA plasma levels as a predictive factor in the development of acute posttraumatic stress disorder

Background Gamma amino-butyric acid (GABA) regulates the intensity and the duration of the central hyperadrenergic response in times of high stress and has been negatively associated with anxiety, depression, and sleep problems. We hypothesized that individuals with low plasma GABA levels may be more prone to develop posttraumatic stress disorder (PTSD) in the aftermath of trauma exposure. Methods To test this hypothesis, we measured plasma GABA levels in a population of 108 road traffic accident victims on arrival at a traumatology department and assessed them for PTSD 6 weeks later. Results The mean GABA level (nmol/mL) in the PTSD group (n = 55; M = .20; SD = .08) was significantly lower compared with members of the trauma-exposed group who did not develop PTSD [n = 17; M = .30; SD = .09), t(70) = 3.94, P = .0002]. Conclusions Provided that GABA levels in the brain are genetically predetermined, our results would suggest that individuals with low plasma GABA levels are premorbidly more vulnerable to stress-related disorders such as acute PTSD. If replicated, plasma GABA levels measured in the aftermath of trauma exposure might help to identify individuals at high risk for developing PTSD.