The BCAAs, particularly leucine, play an important role in mediating amino acid–regulated steps of protein synthesis. To get an idea of the importance of active protein synthesis for the brain structures of TBI patients, it is sufficient to mention that de novo protein synthesis is essential for brain tissue repair, sprouting, and circuitry remodeling. BCAAs may also favor the recovery of cognition indirectly by an insulin-mediated action. This hypothesis is highly plausible, both because BCAAs induce insulin secretion and release and because this hormone crosses the blood-brain barrier, exerting profound effects on the CNS