Biomarkers of cognitive dysfunction in traumatic brain injury.

Acetylcholine, glutamate, dopamine, serotonin (5-HT), gamma-aminobutyric acid, substance P (SP), amyloid-β (Aβ) and neurotrophic protein S100B are arguably the most important cognition-related biomarkers in the brain. Among this list are five neurotransmitters that signal through postsynaptic receptors. Our knowledge of cognition-related biomarkers has been advanced through translational experiments and clinical case-study data. Although these biomarkers are widespread in the brain and pronounced individual variations exist, these biomarkers can be used to identify both acute and chronic abnormalities following traumatic brain injury. Changes in these biomarkers likely indicate damage to brain networks or to key brain cell types that support cognitive functions. Identification of such biomarker abnormalities could result in earlier diagnoses, improved prognoses and therapies that enable neurotransmitters to return to normal levels.