Blast-related traumatic brain injury (TBI) is associated with a variety of mental health disorders in veterans including post-traumatic stress disorder (PTSD) and depression. These conditions have been particularly common in veterans returning from the recent conflicts in Iraq and Afghanistan. Treatments for the chronic symptoms that follow blast-related TBI are currently limited to largely supportive care. We have explored the effects of 74.5-kPa blast exposures that mimic mild TBI (mTBI) in a rat model. Blast-exposed rats exhibited a variety of PTSD-related behavioral traits, including increased anxiety, enhanced acoustic startle, altered responses to a predator scent, and altered cued fear responses that are chronic and persistent. The cerebral vasculature is especially sensitive to blast injury with both acute and chronic vascular pathology being present after blast-exposure. The overall goal of the proposed research is to test whether photobiomodulation therapy using transcranial laser therapy (TLT) can improve the chronic anxiety and PTSD-related behavioral traits observed in blast-exposed rats while ameliorating the underlying vascular pathology. Beneficial effects of TLT have been shown in both humans and animal models for a range of neurological and psychological disorders including TBI. We propose to administer TLT to blast-exposed rats at six months after blast exposure, a time when the PTSD-related behavioral phenotype is well established. We will determine whether TLT can reverse the behavioral effects of blast injury using a testing strategy that will focus on those tests previously found most informative. We will determine using micro-CT scanning, quantitative histopathology and biochemistry whether blast associated vascular pathology can be reversed by TLT. Collectively, these studies will explore the potential therapeutic benefits of transcranial photobiomodulation for the treatment of blast-related behavioral effects. These studies may uncover new therapeutic options for the treatment of veterans affected by the chronic effects of blast-related injury.