Event Related Potentials and its role as Endophenotypes in Psychiatry

Abstract

Familial segregation is a norm rather than an exception in psychiatry. Genetic research has failed to provide much anticipated unanimous, if not awaited answers to the complex predispositions to psychiatric disorders. Hence, the concept of endophenotype took birth. Endophenotype is an attribute which is hidden phenotype, which is described as internal phenotypes discoverable by biochemical test or microscopic examination. This concept was immediately picked up by psychiatry, giving a totally new direction to the search for root cause of various psychiatric disorders.Cognitive deterioration is inseparable from psychiatric disorders, known since dawn of psychiatry. However, cognitive deficits in FDRs (First Degree Relatives) of psychiatric patients were one of the first endophenotypes noted. Event Related Potential (ERP), a science known to be electrophysiological counterpart of various cognitive processes, was soon incorporated in search of endophenotypes in psychiatry. In schizophrenia reduced amplitude of MMN(Mismatch negativity), impaired suppression of P50 and reduced amplitude of P300; reduced P300 amplitude, impaired P50 suppression in Bipolar Affective Disorders; reduced P300 amplitude in substance dependence disorders have been reported to have endophenotypic values. Various other ERP waves such as CNV, N400 have been investigated but no conclusive reports are out yet. The ultimate goal of this science is to search for genes governing the cognitive processes responsible for ERP waves identified as Endophenotypes for specific psychiatric disorders, and the search has just started.
Keywords : Event Related Potential, Endophenotype, Psychiatric Disorder, Mismatch negativity,
P 300, P 50, CNV