Since 2001, more than 1.5 million U.S. military personnel have been deployed to Iraq or Afghanistan. Traumatic brain injury (TBI) has become a major health problem, often referred to as the “signature injury” of these wars and affecting an estimated 320,000 U.S. troops. Although most TBI cases are classified as mild, approximately 30% experience residual symptoms, including headaches and dizziness, depression and irritability, as well as deficits in attention and memory and pronounced slowing of information processing. Of note, 17-30% of TBI survivors also develop PTSD.
The search for markers of brain structure and function that index risk for PTSD has begun only recently, and few studies have examined brain markers of risk for PTSD in mild TBI survivors.
Diffusion tensor imaging is a relatively new technique that is uniquely sensitive to subtle, diffuse white matter changes that correlate with diffuse axonal injury. Structural MRI was used to quantify gray matter, white matter, and cerebrospinal fluid, as well as to examine brain regions expected to be abnormal in patients who go on to develop PTSD.
Event-related brain potentials (ERP) provide a powerful and sensitive method for assessing information processing and have been used frequently to evaluate cognitive changes in TBI survivors.
Studies of neurocognitive performance in PTSD have revealed deficits in executive functions. We propose that deficits in specific neurocognitive functions reflecting aspects of frontal and limbic system integrity will be associated with the development of PTSD.
To evaluate associations between baseline indices of brain structure and function and the course of PTSD symptoms in service members with mild TBI. Measures of brain structure (images derived from MRI and DTI) and brain function (ERPs, neurocognitive performance, and neurological soft signs) were recorded soon after injury (baseline) and 6 months later. Outcome was assessed using the Clinician Administered PTSD Scale (CAPS) as well as post-concussion symptoms and measures of health and well-being, which were administered at baseline and 3 and 6 months later. Subjects were service members who had sustained mild TBI (n = 72 completers); a comparison group comprised service members who had sustained serious injuries but screened negative for TBI (n = 33 completers).
Identifying risk factors for PTSD in survivors of mild TBI and survivors of severe extra-cranial injuries would lead to improvements in the ability to predict the onset of PTSD in wounded warriors and allow interventions to prevent its development. Prevention is more effective and more economical than treatment of a disorder. Furthermore, the longer symptoms persist untreated, the more difficult and treatment-resistant the disorder becomes.