The aim of this research is to determine if the biological fluids (blood/saliva) from chronic brain-injured patients (both blast and non-penetrating TBI) contain reproducible protein markers. To accomplish this two populations of chronic TBI patients who are receiving treatment at The Institute for Research and Rehabilitation (TIRR): blast injury victims and non-penetrating TBI will be studied. Using multiple proteomic approaches including mass spectrometry, multiplex ELISAs, and antibody microarrays, as well as RNA profiling, the investigators aim to identify biomarkers in the blood/saliva of patients suffering from chronic TBI and to determine the similarities/differences between the blast and non-penetrating injury groups. Identification of these biochemical changes will give insight into the long-lasting changes associated with head injury, and may identify new targets for treating the associated pathologies.