| Description |
Currently, our accuracy in predicting the lasting effects of traumatic brain injury (TBI) is low, due to large sample heterogeneity. Possible negative lasting effects of TBI include mental health disorders and substance use disorders (SUDs). Links between TBI, alcohol use, and Post-Traumatic Stress Disorder (PTSD) are not currently well understood but they are highly comorbid among military populations, demonstrating the importance of the deployment context and/or deployment-specific injury mechanisms, such as blast. Through this research, we sought to elucidate possible links between mental illness and SUDs, especially alcohol misuse, and a relationship to the effects of TBI. We used retrospective data analysis of brain imaging and analysis processed by the Long-Term Impact of Military-Relevant Brain Injury Consortium Chronic Effects of Neurotrauma Consortium, a large sample of US military veteran brain imaging (n=1466) (LIMBIC-CENC). This database of military TBI brain imaging allows us to use different brain processing programs, including FreeSurfer, to organize and collect meaningful data on brain structure. We developed a series of models to represent the complex interactions between TBI, PTSD, and alcohol use. The overarching goal is to build an understanding of the mechanisms of common issues that begin after TBI, and even better, to build an understanding of predictors of worse outcomes. To understand alcohol use, we examined AUDIT responses, a test accredited for testing alcohol use and misuse. To understand PTSD, we used the PCL-5 (PTSD Checklist for DSM-5), a standard test to track PTSD symptoms. Brain metrics were considered and differences in brain size between individuals were controlled for by including intracranial volume (ICV) in the models. The project is relevant as it seeks to understand the relationship between the effects of alcohol use and PTSD on TBI through subcortical volume changes. This research utilized models to determine if a combination of variables better predicts outcomes rather than individual variables. We found a significant relationship between higher alcohol use and smaller thalamus size in individuals with mTBI and PTSD. In our initial evaluation, without controlling for age, gender, and ICV, we found no statistical difference in subcortical brain volumes related to alcohol use. However, after controlling for these factors, and using a continuous scale of alcohol use, we found that in individuals with both PTSD and mTBI, there was a statistically significant relationship between higher alcohol consumption and smaller subcortical brain volumes in the thalamus (p<0.05). Our results are limited to generalizing towards the military population because of the military sample. The study has great implications for military TBI and the unseen lasting consequences of the violence of war, even in cases of mild traumatic brain injury. Given the findings of alcohol use and smaller subcortical brain volumes in the thalamus, recommendations for limiting alcohol use in military survivors of mild TBI are warranted. |
