S100B as a Potential Neurochemical Biomarker in a Variety of Neurological, Neuropsychiatric and Neurosurgical Disorders

S100B is a calcium-binding protein found in Schwann cells in the peripheral nervous system, and in astrocytes in the central nervous system. It has multiple functions including the inhibition of protein phosphorylation through interacting with kinase substrates, regulating enzyme activity and interacting with cytoskeletal elements. It is also involved in calcium homeostasis, and is believed to have a role in cytosolic calcium buffering. In recent years it has been shown that S100B is elevated and released into the circulation in a wide variety of neuropathologic states. As such it has generated a great deal of interest as a surrogate biomarker for injury to the CNS. It has been shown to be raised in many organic brain disorders such as traumatic brain injury, subarachnoid haemorrhage, stroke, epilepsy, multiple sclerosis, Parkinson's disease and hydrocephalus. In addition to this there is now clinical and laboratory evidence that it is raised in neuropsychiatric disorders such as schizophrenia, depression, bipolar disorder, anxiety, post-traumatic stress disorder and neuropsychiatric systemic lupus erythematosus. S100B has great potential to become a specific neurological screening tool that is predictive of outcome and reactive to treatments.