Mismatch negativity and cognitive performance in the course of schizophrenia.

BACKGROUND: Cognitive deficits and abnormal event-related brain potentials (ERP) have been proposed as risk markers for the development of schizophrenia. Evidence is inconclusive whether these markers indicate a risk for the development of psychosis or illness progression. METHODS: The present study aimed at further clarification by comparing symptom expression (Brief Psychiatric Rating Scale, BRPS), the ERP Mismatch Negativity (MMN), and neuropsychological performance on the MATRICS Consensus Cognitive Battery between healthy controls (HC, n = 38) and individuals at different stages of illness: individuals at risk for psychosis (ARP, n = 33), patients at first admission, thus, early stage (ES, n = 35), chronic schizophrenia patients (CS, n = 25). Moreover, symptom expression was reassessed for ARP and ES at a 6 months follow-up. RESULTS: MMN was smaller in individuals with manifest psychosis (ES, CS) than in HC, but did not differ between ARP and HC. In contrast, ARP showed similar cognitive deficits as ES and CS, all three groups differing from HC. Lower cognitive performance predicted higher symptom severity at index assessments and 6 months follow-up in ARP and ES, while MMN did not explain additional variance. CONCLUSION: MMN seems to mark manifest psychosis, independent of early or chronic stage, while cognitive deficits mark early present psychopathology in individuals at risk for and with diagnosed psychosis rather than illness progression.

Environmental adversities and psychotic symptoms: The impact of timing of trauma, abuse, and neglect.

BACKGROUND: Trauma and adverse childhood experiences (ACE) occur more often in mental illness, including psychosis, than in the general population. Individuals with psychosis (cases) report a higher number and severity (dose) of adversities than healthy controls. While a dose-dependent increase of adversities has been related to more severe psychopathology, the role of type and timing is still insufficiently understood on the exacerbation of positive and negative psychotic symptoms. Moreover, dissociative symptoms were examined as potential mediator between adversities and severity of psychotic symptoms. METHODS: Exposure to adversities were assessed by interviews in n=180 cases and n=70 controls. In cases, symptom severities were obtained for psychotic symptoms and dissociation. Conditioned random forest regression determined the importance of type and timing of ACE for positive and negative symptom severity, and mediator analyses evaluated the role of dissociative symptoms in the relationship between adversities and psychotic symptoms. RESULTS: Cases experienced substantially more abuse and neglect than controls. Adversities were related in a dose-dependent manner to psychotic disorder. An array of adversities was associated with more severe positive symptoms, while the conditioned random forest regression depicted neglect at age 10 as the most important predictor. Dissociative symptoms mediated the small relation of trauma load in childhood and positive symptoms. CONCLUSION: The role of trauma and ACE on psychotic symptoms can be specified by neglect during frontocortical development in the exacerbation of positive symptoms. The mediating role of dissociation is restricted to the relation of childhood trauma and positive symptoms.