Associations among domains of self-disturbance in schizophrenia

Abnormal Oculomotor Corollary Discharge Signaling as a Trans-diagnostic Mechanism of Psychosis

BACKGROUND AND HYPOTHESIS

Corollary discharge (CD) signals are "copies" of motor signals sent to sensory areas to predict the corresponding input. They are a posited mechanism enabling one to distinguish actions generated by oneself vs external forces. Consequently, altered CD is a hypothesized mechanism for agency disturbances in psychosis. Previous studies have shown a decreased influence of CD signals on visual perception in individuals with schizophrenia-particularly in those with more severe positive symptoms. We therefore hypothesized that altered CD may be a trans-diagnostic mechanism of psychosis.

STUDY DESIGN

We examined oculomotor CD (using the blanking task) in 49 participants with schizophrenia or schizoaffective disorder (SZ), 36 bipolar participants with psychosis (BPP), and 40 healthy controls (HC). Participants made a saccade to a visual target. Upon saccade initiation, the target disappeared and reappeared at a horizontally displaced position. Participants indicated the direction of displacement. With intact CD, participants can make accurate perceptual judgements. Otherwise, participants may use saccade landing site as a proxy of pre-saccadic target to inform perception. Thus, multi-level modeling was used to examine the influence of target displacement and saccade landing site on displacement judgements.

STUDY RESULTS

SZ and BPP were equally less sensitive to target displacement than HC. Moreover, regardless of diagnosis, SZ and BPP with more severe positive symptoms were more likely to rely on saccade landing site.

CONCLUSIONS

These results suggest that altered CD may be a trans-diagnostic mechanism of psychosis.

"Feeling shattered and ephemeral": How do positive and negative symptoms affect self-concept clarity among individuals experiencing psychosis?

PURPOSE

Incoherence in sense of self in schizophrenia may mask individuals' ability to perceive reality accurately, and cause them to feel alienated from themselves and others. This descriptive correlational study investigates the relationship between positive and negative symptoms in relation to self-concept clarity (SCC) in schizophrenia.

METHOD

A sample of 200 inpatients with schizophrenia were recruited to complete the Self-Concept Clarity Scale and were rated on the Brief Psychiatric Rating Scale (BPRS-version 4.0).

RESULTS

A strong inverse correlation between positive and negative symptoms in relation to SCC (r = 0.242, P < 0.001, and r = 0.225, P = 0.001, respectively).

CONCLUSION

The overall BPRS scores were identified as independent precursors of low SCC.

Anomalous self-experiences in cognition are negatively associated with neurocognitive functioning in schizophrenia

INTRODUCTION

Anomalous self-experiences (ASEs) are disturbances in the subjective experience of the self and are common in people with schizophrenia. Theorists have suggested that ASEs may underlie the neurocognitive deficits that are also common in people with schizophrenia; however, few studies have empirically investigated the relationship between these variables. Thus, the current study aimed to determine whether self-reported ASEs, particularly disturbances in cognitive or mental experiences, are meaningfully related to neurocognitive performance in individuals with schizophrenia.

METHODS

48 individuals with schizophrenia and 34 healthy comparison participants completed the Inventory of Psychotic-Like Anomalous Experiences (IPASE), which is composed of five subscales including disturbances in cognition, and the MATRICS Consensus Cognitive Battery (MCCB).

RESULTS

Participants with schizophrenia performed worse than controls on each MCCB domain and had higher ASE scores on the total IPASE and all five subscales. Only the IPASE-Cognition subscale was associated with cognitive performance. Specifically, IPASE-Cognition was negatively correlated with scores in attention, visual learning, reasoning, and working memory.

CONCLUSIONS

These results suggest that self-reported subjective disturbances in cognition may be meaningfully associated with several objectively-measured domains of neurocognition. Severity of ASEs may therefore be an important consideration when analysing the extent of cognitive deficits in schizophrenia.

The Self in the Spectrum: A Meta-analysis of the Evidence Linking Basic Self-Disorders and Schizophrenia

Disturbed self-experience has been reported as a characteristic feature of schizophrenia since the first formulation of its diagnostic concept; however, only in the last 2 decades an explicit notion of basic Self-disturbance, or Self-Disorders (SD), has emerged as target for a systematic research program. We conducted systematic searches in bibliographical databases to identify cross-sectional studies that explored SD across different diagnostic groups and explored diagnostic ascription within or outside schizophrenia spectrum disorders (SSD) as main outcome. Data were pooled using fixed- and random-effects meta-analysis models. Heterogeneity was assessed using stratified meta-analyses and meta-regression. Of 218 identified studies, 32 were included in the systematic review and 27 in the meta-analysis. Patients diagnosed with SSD scored higher on measures of SD than healthy controls (HC) (Hedges' g = 1.8; 95% CI = 1.5 to 2.0), individuals diagnosed with other mental illness (OMI) (1.9; 1.6 to 2.2), bipolar or affective disorders (1.8; 1.4 to 2.2), and clinical high risk for psychosis (CHR) (1.6; 0.9 to 2.4). Patients with schizotypy or schizotypal personality disorder scored higher on measures of SD than OMI (1.5; 1.3 to 1.8) and HC (1.4; 1.1 to 1.7). Patients with first-episode psychosis scored higher on measures of SD than HC (2.5; 2.1 to 2.9) and OMI (1.6; 1.2 to 2.1). Subjects at CHR scored higher on measures of SD than HC (2.0; 1.7 to 2.2) and OMI (19; 1.6 to 2.2). Overall, heterogeneity ranged from negligible to high, especially in comparisons of the target group with OMI, probably as a reflection of the immanent diagnostic heterogeneity of this group. The findings suggest that SD selectively aggregate within schizophrenia spectrum disorders as compared to other mental disorders and that they could be a central phenotypic marker of vulnerability to schizophrenia across the different shades of severity of its spectrum of disorders.

Visual-Tactile Spatial Multisensory Interaction in Adults With Autism and Schizophrenia

Background: Individuals with autism spectrum disorder (ASD) and schizophrenia (SZ) exhibit multisensory processing difficulties and social impairments, with growing evidence that the former contributes to the latter. However, this work has largely reported on separate cohorts, introducing method variance as a barrier to drawing broad conclusions across studies. Further, very few studies have addressed touch, resulting in sparse knowledge about how these two clinical groups may integrate somatic information with other senses. Methods: In this study, we compared adults with ASD (n = 29), SZ (n = 24), and typical developmental histories (TD, n = 37) on two tasks requiring visual-tactile spatial multisensory processing. In the first task (crossmodal congruency), participants judged the location of a tactile stimulus in the presence or absence of simultaneous visual input that was either spatially congruent or incongruent, with poorer performance for incongruence an index of spatial multisensory interaction. In the second task, participants reacted to touch in the presence or absence of dynamic visual stimuli that appeared to approach or recede from the body. Within a certain radius around the body, defined as peripersonal space (PPS), an approaching visual or auditory stimulus reliably speeds reaction times (RT) to touch; outside of this radius, in extrapersonal space (EPS), there is no multisensory effect. PPS can be defined both by its size (radius) and slope (sharpness of the PPS-EPS boundary). Clinical measures were administered to explore relations with visual-tactile processing. Results: Neither clinical group differed from controls on the crossmodal congruency task. The ASD group had significantly smaller and more sharply-defined PPSs compared to the other two groups. Small PPS size was related to social symptom severity across groups, but was largely driven by the TD group, without significant effects in either clinical group. Conclusions: These results suggest that: (1) spatially static visual-tactile facilitation is intact in adults with ASD and SZ, (2) spatially dynamic visual-tactile facilitation impacting perception of the body boundary is affected in ASD but not SZ, and (3) body boundary perception is related to social-emotional function, but not in a way that maps on to clinical status.

The placement of anomalous self-experiences within schizotypal personality in a nonclinical sample

Anomalous self-experiences are disturbances in the subjective experience of the self and have been shown to be related to the premorbid, prodromal, acute, and chronic phases of schizophrenia-spectrum disorders. Despite having a long history in psychopathology research, anomalous self-experiences are not explicitly represented in any major nosology of mental disorders. Previous research suggests that anomalous self-experiences are correlated, but distinct from other aspects of schizotypal personality, but this has not been examined with confirmatory factor analysis. The current research aimed to examine where anomalous self-experiences fit within the structure of schizotypal personality including cognitive-perceptual, interpersonal, disorganized, and paranoid factors. It also examined the measurement invariance of the factor structure across ethnicity and between sexes. Seven hundred forty-four participants completed multiple measures of anomalous self-experiences and schizotypal personality. The best fitting model was a five-factor model with anomalous self-experiences, cognitive-perceptual, interpersonal, disorganized, and paranoid factors. This model fit better than models with anomalous self-experiences loading on any of the four schizotypal personality factors. The structure had configural, metric, and scalar invariance across race/ethnicities, but lacked scalar invariance between sexes. Anomalous self-experience scores did not differ among race/ethnicity or between sexes. These results suggest that anomalous self-experiences are highly correlated with but distinct from other facets of schizotypal personality. Future research may examine whether anomalous self-experiences should be added to nosologies of psychotic-spectrum disorders.

A combination of self-disturbances and psychotic-like experiences. A cluster analysis study on a non-clinical sample in Poland

We aimed to perform a cluster analysis to investigate the group structure of a combination of psychotic-like experiences (PLEs) and self-disturbances in a non-clinical sample. Non-clinical adults (n = 677) were assessed with the Community Assessment of Psychic Experiences (CAPE), the Davos Assessment of Cognitive Biases Scale (DACOBS) and the Inventory of Psychotic-Like Anomalous Self-Experiences (IPASE). Cluster analysis was conducted based on the positive and negative dimension of CAPE and a total score of IPASE. Four distinct groups were revealed by the cluster analysis. The High Profile group had the highest means, and the Low Profile had the lowest scores of positive and negative subscales of the CAPE and IPASE. The Positive Profile group had a significantly higher level of self-disturbances (in 'Cognition', 'Consciousnesses and 'Somatization' dimensions) from participants with the 'Negative Profile'. The High Profile group had more cognitive biases (i.e., inadequate cognitive inference about internal and external events) related to psychosis as assessed with DACOBS, had the highest means on each IPASE subscale and had a higher level of emotional distress. A combination of high level of PLEs and self-disturbances may capture the highest risk of psychosis in the general population associated with cognitive biases characteristic for psychosis.