Paranoid induction reduces N400s of healthy subjects with delusional‐like ideation

Abstract

A previous study suggests that the amplitude of the N400 event-related potentials (ERPs) of healthy subjects does not vary with their delusional-like ideations. This contrasts with the smaller N400 amplitudes observed in more- than in less-deluded schizophrenia patients. Here, we hypothesize that these smaller N400 amplitudes were related to the paranoid feelings patients had during the ERP recording. We thus induced this type of feelings in healthy subjects. Delusional-like ideation was assessed with the schizotypal personality questionnaire. Thirty-four healthy subjects completed a semantic categorization task. Paranoid feelings were significantly enhanced by the induction. In these conditions, greater delusional-like ideation scores were associated with smaller N400 amplitudes and larger late positive components. Controlling for the two other schizotypal factors strengthened these results. These findings may help us understand why delusions persist.

Paranoid males have reduced lateralisation for processing of negative emotions: An investigation using the chimeric faces test

“…This was particularly the case for participants who scored highly on the ''interpersonal'' scale, one component of which is paranoid ideation. This result is consistent with the work of Mucci et al (2005) in showing reduced 238 BOURNE AND McKAY lateralisation in individuals with paranoia, although Prevost et al (2011) did not consider possible sex differences in their findings. Nunn and Peters (2001) looked at the relationship between language lateralisation and scores on the various scales of the O-LIFE measure of schizotypy (Oxford-Liverpool Inventory of Feelings and Experiences: Mason, Claridge, & Jackson, 1995) in a non-clinical sample.…”

“…Second, it suggests that there may be sex differences in the relationship between non-clinical levels of schizotypic traits and lateralisation. In another study, using event related potentials, a reduction in the left N400 response was found when a state of paranoia was induced (Prevost et al, 2011). This was particularly the case for participants who scored highly on the ''interpersonal'' scale, one component of which is paranoid ideation.…”

Schizotypal traits and N400 in healthy subjects

“…These results are at odds with the findings of Debruille et al (2007) and Kiang et al (2007) in schizophrenia patients and could be used to support a distinction between normal population and schizophrenia patients in contrast with the idea of a continuum between the two (Garety, Bebbington, Fowler, Freeman, & Kuipers, 2007; Shevlin et al, 2007; Verdoux & van Os, 2002). However, the results of Prévost, Rodier, Lionnet, Brodeur, King, and Debruille (forthcoming) suggest that smaller N400s can be found in healthy subjects with high scores on delusion‐like ideation items of the SPQ, when boosting paranoid feelings, which probably diminishes some of the differences between schizophrenia patients and healthy subjects.…”

Behavioral and brain measures (N400) of semantic priming in patients with schizophrenia: Test–retest effect in a longitudinal study

“…The severity of SP abnormalities has been found to be correlated with that of several clinical features: TD, positive symptoms, delusional‐like ideation, as well as with negative symptoms …”