Application of Electroencephalography to the Study of Cognitive and Brain Functions in Schizophrenia

The electroencephalogram (EEG) recorded from the human scalp is widely used to study cognitive and brain functions in schizophrenia. Current research efforts are primarily devoted to the assessment of event-related potentials (ERPs) and event-related oscillations (EROs), extracted from the ongoing EEG, in patients with schizophrenia and in clinically unaffected individuals who, due to their family history and current mental status, are at high risk for developing schizophrenia. In this article, we discuss the potential usefulness of ERPs and EROs as genetic vulnerability markers, as pathophysiological markers, and as markers of possible ongoing progressive cognitive and cortical deterioration in schizophrenia. Our main purpose is to illustrate that these neurophysiological measures can offer valuable quantitative biological markers of basic pathophysiological mechanisms and cognitive dysfunctions in schizophrenia, yet they may not be specific to current psychiatry's diagnosis and classification. These biological markers can provide unique information on the nature and extent of cognitive and brain dysfunction in schizophrenia. Moreover, they can be utilized to gain deeper theoretical insights into illness etiology and pathophysiology and may lead to improvements in early detection and more effective and targeted treatment of schizophrenia. We conclude by addressing several key methodological, conceptual, and interpretative issues involved in this research field and by suggesting future research directions

Migration Status, Familial Risk for Mental Disorder, and Schizotypal Personality Traits

Markedly raised incidence rates of schizophrenia and other psychotic disorders have been observed in several migrant and ethnic minority groups. To contribute to a better understanding of the elevated risk for psychotic disorders that is conferred by migration status, the present study examined effects associated with migration risk status on schizotypal personality traits, which are thought to reflect an underlying vulnerability to psychotic disorder. Effects of migration status were also compared to effects associated with a family history of psychopathology, which represents a robust nonspecific risk factor. We assessed schizotypal traits, using the Schizotypal Personality Questionnaire (SPQ), in a community-based sample of 62 Moroccan migrants and 41 Dutch nonmigrants, who were classified by the presence or absence of a family history of psychopathology. Overall, Moroccan migrants obtained higher SPQ scores than Dutch nonmigrants. However, migrants who had been classified as having a familial load of psychopathology displayed higher SPQ scores than migrants without such a family history, who in turn did not differ from Dutch nonmigrants. Furthermore, migrants with a familial load, relative to migrants without such a family history, reported higher levels of substance use and feelings of anxiety or depression, and perceived more often ethnic discrimination, which closely paralleled their SPQ scores. These findings indicate that primarily those migrants who are both intrinsically vulnerable and chronically exposed to social adversity, particularly ethnic discrimination, are at elevated risk for psychotic and other disorders. The results add to the evidence that migration status and perceived discrimination are associated with mental health