Amino Acid Supplementation in Recovery From Traumatic Brain Injury (TBIS)

Traumatic brain injury (TBI) is a leading cause of death and disability in young people. It has been called the "signature wound" of the Iraq war because of its frequency among troops. TBI is associated with many chronic disabilities. Physical alterations include reduced exercise tolerance and profound muscle weakness, whereas psychological alterations include diminished sense of well-being, depression, fatigue and anxiety. Muscle and brain tissues rely upon circulating blood amino acids as precursors for metabolic functions. The investigators have shown that even one year after injury, plasma valine, an essential amino acid (EAA), was markedly reduced in patients with TBI compared to healthy controls. The investigators speculate that low plasma valine concentration contributes to chronic fatigue after TBI, since valine and tryptophan compete for the same transporter into the brain, and a low plasma valine concentration will allow more tryptophan to be transported. As a consequence, increased brain tryptophan will increase serotonin production, which may significantly contribute to the development of fatigue. Thus, the investigators will test if restoring valine concentration in persons with TBI may reduce fatigue perception and improve physical and neuropsychological function. Further, the investigators have previously shown that EAA intake has an anabolic effect in healthy young and elderly individuals. However, no data are currently available in persons recovering from TBI. Thus,the investigators will also test if EAA and/or valine can improve muscle mass in patients with TBI.

TBI patients are deficient in a number of essential amino acids (EAA) post injury and we have shown that TBI patient are deficient in valine up to 17 months post injury. We propose to assess plasma amino acid concentrations in TBI patients who are receiving EAA supplementation or valine supplementation compared to placebo patients.

Reduced plasma EAAs may be related to the psychological and metabolic complications associated with TBIs. We aim to assess measures of psychological and physical functionality in TBI patients receiving EAA supplementation.

Inclusion Criteria: Presence of traumatic brain injury Age 18-65 years Ability to sign informed consent >3 months post-injury, <36 months post-injury Ambulatory or require minimal to moderate assistance for safe ambulation Exclusion Criteria: Subjects with cardiac abnormalities considered exclusionary by the study physicians Subjects with uncontrolled metabolic disease, including liver or renal disease Subjects with cancer or recently (6 months) treated cancer other than basal cell carcinoma Any subject currently on a weight-loss diet or a body mass index >34 kg/m2 Recent anabolic or corticosteroids use (within 3 months) Dementia Inability to tolerate an upright position Postural reflexes prohibiting ambulation and inability to follow 2-step commands Any other condition or event considered exclusionary by the PIs and covering physician