Elevated resting heart rate as a predictor of posttraumatic stress disorder after severe traumatic brain injury

Objective: This study indexed the relationship between resting heart rates (HRs) after injury and subsequent posttraumatic stress disorder (PTSD) in patients who sustained severe traumatic brain injury (TBI). Methods: Patients who sustained a severe TBI (N = 68) had their resting HR assessed 1 week and 1 month after injury, and they were assessed for PTSD 6 months after injury with the PTSD Inter-view, a structured clinical interview based on the criteria of the Diagnostic and Statistical Manual of Mental Disorders, 3rd Edition, Revised. Results: PTSD was diagnosed in 23% of patients. PTSD participants had higher HRs at 1 week but not at 1 month after trauma than non-PTSD participants. This difference remained significant when the effect of posttraumatic amnesia was controlled, but it was not significant when the effect of Glasgow Coma Scale was controlled. Conclusion: These findings accord with the proposal that fear conditioning can occur outside the level of awareness and contribute to PTSD development.