by Internet Medical Society
In medicine, a biomarker can be a traceable substance that is introduced into an organism as a means to examine organ function or other aspects of health. It can also be a substance whose detection indicates a particular disease state, for example, the presence of an may indicate an . More specifically, a biomarker indicates a change in expression or state of a protein that correlates with the risk or progression of a disease, or with the susceptibility of the disease to a given treatment.
Biochemical biomarkers are often used in , where they are derived from bodily fluids that are easily available to the early phase researchers.
Other biomarkers can be based on mesures of the electrial activity of the brain (using or ), or volumetric measures of certain brain regions (using ). During recent years a huge effort is being done in the identification of biomarkers for neurological diseases (read a review).