The Combat Polytrauma Triad: Photosensitivity as a Link Between PTSD and Chronic Pain After TBI
Abstract
Veterans who have sustained a traumatic brain injury (TBI) are particularly likely to experience both chronic pain and posttraumatic stress disorder (PTSD), a combination referred to as the polytrauma clinical triad. Chronic pain and PTSD can occur together subsequent to even mild TBI and have significant, long-lasting (decades) impact on both psychological and physical function. Effective treatments for PTSD and pain subsequent to TBI are limited, in part due to incomplete understanding of the brain mechanisms that tie these outcomes together after TBI. However, symptoms of PTSD and pain are mutually reinforcing, and one clue comes from the considerable overlap between brain circuits implicated in PTSD and those contributing to chronic pain. My laboratory has shown in animal studies that brain circuits contributing to chronic pain can be activated by psychological stress and by light, causing increased sensitivity to pain in both cases. We now have preliminary evidence from a largely Veteran population that elevated sensitivity to light is associated with chronic pain and pain-related disability, and that light is processed differently in individuals with high-impact chronic pain. These individuals with high-impact chronic pain are more likely to report PTSD symptoms and to endorse elevated levels of depression, sleep-disturbances, and other disability. The goal of the proposed experiments is to determine whether photosensitivity could serve as a marker of PTSD and high-impact chronic pain after TBI. This marker would be quantitative and free from the stigma felt by individuals endorsing PTSD or pain. Our objectives are to quantify sensitivity to light in Veterans with TBI with and without associated PTSD, and determine whether photosensitivity is associated with greater pain and pain-related disability, poor sleep, and poor functional outcomes in individuals living with PTSD and pain. We will also use functional brain imaging (brain scans) to determine whether a dim light stimulus can activate the pain-related brain regions in Veterans who have PTSD after TBI compared to those with TBI without PTSD. This would be strong evidence that pain pathways in the brain are changed in individuals who suffer from PTSD following a TBI. The proposed project will help us better Understand PTSD and chronic pain after TBI. Pain in the absence of identifiable peripheral triggers is no longer dismissed as imaginary by most physicians, but underlying mechanisms are only now beginning to emerge with the concept of brain changes contributing to chronic pain. This work could thus provide insights into the mechanisms connecting pain and PTSD after TBI, and ultimately help identify individuals whose pain is caused by underlying brain changes. This project also has relevance to Prevention of PTSD and pain after TBI by providing a quantitative measure that has the potential to link PTSD with chronic pain after TBI, identifying individuals with highest risk. If we are correct, photosensitivity could be developed as a quantitative marker of brain changes contributing to PTSD and pain in Veterans with TBI, guiding their treatment and serving as a measure of their responses to different therapies. This work would also provide a better understanding of the brain mechanisms of pain in individual Veterans with chronic pain or PTSD, giving us a simple, inexpensive test that could be applied in a standard clinical setting, and, importantly, validating these hard-to-explain symptoms. Because this test would provide us with a window into brain function, this could guide pharmacological treatments that act directly upon these brain mechanisms and reduce the need for unnecessary surgical procedures or chronic non-specific opioid use. Finally, these studies could pave the way for modifying the light environment as a way to improve pain, functional outcomes, and quality of life for these Veterans.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jan 04, 2024
- Source ID
- HT94252310703
Entities
People
- Mary Heinricher
Organizations
- Oregon Health & Science University
- United States Army