Biomarkers are molecules that can be measured in accessible biological fluids that reflect physiological, pharmacological, or disease processes and can suggest the etiology of, susceptibility to, activity levels of, or progress of a disease. Biomarkers have historically been critical to patient progress in a broad range of clinical conditions. Diagnostic and therapeutic advances in fields as disparate as cardiology and oncology have relied on the ability to measure biomarkers that are reliable indicators of the underlying pathology. The absence of validated biomarkers in the neurotrauma field is a major factor limiting our understanding of the natural history and the long-term effects of traumatic brain injury (TBI), as well as a barrier to drug development in this area. According to the US Food and Drug Administration,1,2 biomarkers fall into the following 4 categories, which are not mutually exclusive: diagnostic, prognostic, predictive, and pharmacodynamic. Diagnostic biomarkers measure disease characteristics that categorize a person by the presence or absence of a specific physiological or pathophysiological state. Prognostic biomarkers are baseline measurements that categorize patients by degree of risk for disease progression and inform about the natural history of the disorder. Predictive biomarkers are baseline characteristics that categorize patients by their likelihood of response to a particular treatment. Finally, pharmacodynamic biomarkers are dynamic measurements that show that biological response has occurred in a patient after a therapeutic intervention.
Bogoslovsky T, Diaz-Arrastia R. Dissecting Temporal Profiles of Neuronal and Axonal Damage After Mild Traumatic Brain Injury. JAMA Neurol. 2016;73(5):506-507. doi:10.1001/jamaneurol.2016.0290