Psychopathological and neuropsychological correlates of source monitoring impairment in schizophrenia

Abstract 

Schizophrenic patients are known to show a deficit in the source monitoring function, which refers to the set of processes involved in the attribution of an origin to memories and beliefs. A failure in source monitoring was found to be associated with Schneiderian delusions in the recent literature. This study aimed to explore in a sample of schizophrenic patients and controls two aspects of the source monitoring process–recognition and source attribution– and their possible correlation with psychopathology and basic neuropsychological performances. A group of 45 stabilized schizophrenic patients and 54 normal volunteers were studied with a Source Monitoring Task and a battery of neurocognitive functions known to be disturbed in schizophrenia. Recognition of self-generated items was significantly worse than control values in Schneiderian delusional patients only, while source attribution of recognized self-generated items was significantly biased towards the external sources in all delusional patients in comparison to controls. Among schizophrenic patients, source misattribution of self-generated items was significantly correlated to an executive, planning performance. Both performances were correlated to verbal memory in controls. Results confirm an impairment of different subcomponents of source monitoring performance in schizophrenia, heterogeneously related to psychopathological features and neuropsychological performances known to be impaired in schizophrenia.

Keywords: Source monitoring, Schizophrenia, Delusions, Memory, Executive function