Association of Amino Acid Prevalence and Chronic Brain Injury

Years after a suffering a brain injury, individuals remain in a physically and cognitively impaired state. The investigators believe that the concentrations of amino acids in the blood are chronically altered and yield negative effects on the individuals health. Preliminary data has shown significantly lower concentrations of amino acids in serum samples from the TBI population, these diminished levels of amino acids may be due to changes in the microbiome. Understanding these changes will help guide rehabilitative services for this population. Individuals with a chronic brain injury will donate samples of blood, oral tissue, and fecal matter to be compared to that of non-injured individuals. Genetic information from the hosts will be striped and discarded; participant's genetic information will not be retained. To better understand changes in the microbiome, any history of antibiotics and probiotics will be assessed.

The purpose of this study is to evaluate the levels of Amino Acids in adult individuals with chronic (\> 2 years) traumatic brain injury (TBI) when compared to a non-brain injured cohort population. Preliminary data from an assay of amino acids in individuals with chronic TBI compared to an assay of individuals without a TBI revealed significantly lower concentrations of amino acids within the TBI group. The composition and structure of the oral and fecal microbiome will be determined by 16S rDNA sequencing. Taxonomic and community structure profiles will be treated as outcome variables and modeled together with the participant's plasma amino acid concentration, years post-injury, age, sex and other variables to determine correlations. These correlations may improve our understanding of the diminished amino acid metabolism within the chronic TBI population. The endpoint will identify the microbiome structure and composition by 16S rRNA gene sequencing within the TBI and healthy participants and to assess the participant's amino acid concentrations and other participant demographics and phenotypic characteristics (years post-injury, age, sex). This comparison may improve our understanding of the diminished amino acid metabolism within the chronic TBI population.