Functional and Structural Endophenotypes in Schizophrenia

Abstract

Various studies show that a longer duration of untreated psychosis relates to a worse prognosis. Thus the early recognition of schizophrenia seems a crucial challenge. However, many clinical symptoms of prodromal schizophrenia stages are not sufficiently specific. Here we present an overview over recent contributions of neuroimaging and electrophysiological as well as genetic studies: Which additional information offer endophenotypes (such as P300, P50 sensory gating, MMN, smooth pursuit eye movements; indicating a specific genetic vulnerability) together with a better understanding of schizophrenic pathophysiology (state-dependent biological markers, e.g. aggravated motor neurological soft signs during psychosis) in prodromal schizophrenia when still ambiguous clinical symptoms are present. Examples (e.g. from COMT polymorphisms to working memory deficits) are given to illustrate more specific underlying neuronal mechanisms behind behavioural symptoms. This way, a characteristic pattern of disturbed cerebral maturation might be distinguished in order to complement clinical instruments of early schizophrenia detection. While today, the specificity and sensitivity of the aforementioned markers does still not allow diagnosing all the heterogeneous forms of the schizophrenic syndrome, it seems a promising approach to define specific high-risk constellations for subgroups of patients to allow timely early interventions when they are justified. The main focus of this chapter will be to connect clinical symptoms with genetic findings via endophenotypes and to give an impression how clinical early recognition attempts could be complemented by functional and structural endophenotypes that could serve as diagnostic markers. State markers and endophenotypes as a specific kind of trait marker are compared, possibilities and limitations with respect to sensitivity and specificity are discussed. (PsycINFO Database Record (c) 2019 APA, all rights reserved)