Figure 7. Creatine and cyclocreatine in brain function.

(A) The creatine/CK system is essential for shuttling energy from sites of energy production to sites of energy use. Creatine and phosphocreatine can modulate energy metabolism at the mitochondria and glycolytic pathways. When creatine is absent, energy supply can be insufficient or slow during energy demands. Having cyclocreatine and phospholylated cyclocreatine keeps ATP levels more constant and decreases pathophysiological consequences. (B) In contrast to the transport and use of creatine by the normal brain, with CRT deficiency, creatine cannot enter the brain, resulting in poor speech and cognition. In the cyclocreatine-treated CRT deficiency brain, cyclocreatine enters brain cells and works with the cell’s metabolism to improve speech and cognition.