Consensus paper of the WFSBP Task Force on Biological Markers: Criteria for biomarkers and endophenotypes of schizophrenia part I: Neurophysiology

Abstract

The neurophysiological components that have been proposed as biomarkers or as endophenotypes for schizophrenia can be measured through electroencephalography (EEG) and magnetoencephalography (MEG), transcranial magnetic stimulation (TMS), polysomnography (PSG), registration of event-related potentials (ERPs), assessment of smooth pursuit eye movements (SPEM) and antisaccade paradigms. Most of them demonstrate deficits in schizophrenia, show at least moderate stability over time and do not depend on clinical status, which means that they fulfil the criteria as valid endophenotypes for genetic studies. Deficits in cortical inhibition and plasticity measured using non-invasive brain stimulation techniques seem promising markers of outcome and prognosis. However the utility of these markers as biomarkers for predicting conversion to psychosis, response to treatments, or for tracking disease progression needs to be further studied.

Royal Australian and New Zealand College of Psychiatrists clinical practice guidelines for the management of schizophrenia and related disorders

“…In addition, experts in specific areas contributed to the relevant sections. The working group considered recent international CPGs, including the UK National Institute for Health and Care Excellence (NICE) (2014) clinical guideline on the treatment and management of psychosis and schizophrenia in adults and the World Federation of Societies of Biological Psychiatry guidelines for the biological treatment of schizophrenia (Hasan et al, 2012(Hasan et al, , 2013(Hasan et al, , 2015Thibaut et al, 2015). The staging model (McGorry et al, 2006) provided a framework for assessment and clinical management and for the choice and timing of interventions.…”

“…Research into the various forms of schizophrenia has been assisted by the conceptual tool of endophenotypes, which are heritable, objectively measurable biological traits that co-segregate with clinical illness in pedigrees and may also be expressed in unaffected members. Endophenotypes include distinct patterns on neuropsychological tests of cognitive function, brain electrophysiological measures and neuroimaging variables (Thibaut et al, 2015). Measures of cognitive deficit, including deficits in memory and attention, executive function and sensory gating, have been shown to be particularly sensitive to the dysfunction that sets people with schizophrenia apart from healthy controls (Nuechterlein et al, 2012).…”

Consensus paper of the WFSBP Task Force on Biological Markers: Criteria for biomarkers and endophenotypes of schizophrenia part II: Cognition, neuroimaging and genetics

“…In general, these measurements differ significantly between groups, are robust, reliable and state independent (except for P300 amplitude) and can be used as neurophysiological endophenotypes for genetic studies (Light et al 2012;Swerdlow et al 2015;Thibaut et al 2015).…”

“…In the context of low correlation between phenotype and genotype in schizophrenia, these quantitative measurements could provide intermediate links between genetic variations and clinical phenotypes. Some neuropsychological endophenotypes have been widely studied in schizophrenia (Swerdlow et al 2015;Thibaut et al 2015) and seem promising for both diagnosis (Louchart-de la Chapelle et al 2005;Thibaut et al 2015) and measurement of functional outcome or response to treatment (Arfken et al 2009;Light et al 2012). Among neurophysiological endophenotypes, the largest effect sizes (with Cohen's d effect size >1.5) were reported in schizophrenia patients for neuromotor deviation, auditory-evoked P50 paradigms, functional magnetic resonance imaging (fMRI) activation during the 2-back task, the Continuous Performance Test (CPT) and oculomotor-delayed response (Allen et al 2009).…”

Dissociable auditory mismatch response and connectivity patterns in adolescents with schizophrenia and adolescents with bipolar disorder with psychosis: A magnetoencephalography study

“…Electrophysiological techniques (Thibaut et al, 2015) can help determine biomarkers at the neuronal level. Of particular relevance are passive event related potentials (ERPs) in response to auditory oddball paradigms.…”