Peripersonal Space Plasticity in Relation to Psychopathology and Anomalous Subjective Experiences in Individuals With Early-Onset and Adult-Onset Schizophrenia.

INTRODUCTION: Individuals with schizophrenia present anomalies in the extension and plasticity of the peripersonal space (PPS), the section of space surrounding the body, shaped through motor experiences. A weak multisensory integration in PPS would contribute to an impairment of self-embodiment processing, a core feature of the disorder linked to specific subjective experiences. In this exploratory study, we aimed at: (1) testing an association between PPS features, psychopathology, and subjective experiences in schizophrenia; (2) describing the PPS profile in individuals with early-onset schizophrenia. MATERIALS AND METHODS: Twenty-seven individuals with schizophrenia underwent a task measuring the PPS size and boundaries demarcation before and after a motor training with a tool. The Positive And Negative Syndrome Scale (PANSS), the Examination of Anomalous Self Experience scale (EASE) and the Autism Rating Scale (ARS) were used to assess psychopathology. Subsequently, participants were divided into two subgroups, early and adult-onset schizophrenia. The two groups were compared in regard to their PPS and psychopathological profiles. RESULTS: PPS patterns were associated with psychopathology, particularly positively with PANSS negative scale score, and negatively with subjective experiences of existential reorientation (EASE Domain 5 scores) and of social encounters (ARS scores). Only PPS parameters and ARS scores differentiated between early and adult-onset participants. CONCLUSIONS: Our results, although preliminary and exploratory, can suggest a link between PPS patterns, negative symptoms, and disturbances of the subjective experience, particularly in the intersubjective domain, in schizophrenia. Moreover, they seem to suggest that specific PPS profiles and schizophrenic autism traits could be markers of early-onset schizophrenia.

Language in interaction: turn-taking patterns in conversations involving individuals with schizophrenia.

Individuals with schizophrenia generally show difficulties in interpersonal communication. Linguistic analyses shed new light on speech atypicalities in schizophrenia. However, very little is known about conversational interaction management by these individuals. Moreover, the relationship between linguistic features, psychopathology, and patients' subjectivity has received limited attention to date. We used a novel methodology to explore dyadic conversations involving 58 participants (29 individuals with schizophrenia and 29 control persons) and medical doctors. High-quality stereo recordings were obtained and used to quantify turn-taking patterns. We investigated psychopathological dimensions and subjective experiences using the Positive and Negative Syndrome Scale for Schizophrenia (PANSS), the Examination of Anomalous Self Experience scale (EASE), the Autism Rating Scale (ARS) and the Abnormal Bodily Phenomena questionnaire (ABPq). Different turn-taking patterns of both patients and interviewers characterised conversations involving individuals with schizophrenia. We observed higher levels of overlap and mutual silence in dialogues with the patients compared to dialogues with control persons. Mutual silence was associated with negative symptom severity; no dialogical feature was correlated with anomalous subjective experiences. Our findings suggest that individuals with schizophrenia display peculiar turn-taking behaviour, thereby enhancing our understanding of interactional coordination in schizophrenia.

Tool-use Extends Peripersonal Space Boundaries in Schizophrenic Patients.

BACKGROUND AND HYPOTHESIS: A primary disruption of the bodily self is considered a core feature of schizophrenia (SCZ). The "disembodied" self might be underpinned by inefficient body-related multisensory integration processes, normally occurring in the peripersonal space (PPS), a plastic sector of space surrounding the body whose extent is altered in SCZ. Although PPS is a malleable interface marking the perceptual border between self and others, no study has addressed the potential alteration of its plasticity in SCZ. We investigated the plasticity of PPS in SCZ patients after a motor training with a tool in the far space. STUDY DESIGN: Twenty-seven SCZ patients and 32 healthy controls (HC) underwent an audio-tactile task to estimate PPS boundary before (Session 1) and after (Session 3) the tool-use. Parameters of PPS, including the size and the slope of the psychometric function describing audio-tactile RTs as a function of the audio-tactile distances, were estimated. STUDY RESULTS: Results confirm a narrow PPS extent in SCZ. Surprisingly, we found PPS expansion in both groups, thus showing for the first time a preserved PPS plasticity in SCZ. Patients experienced a weaker differentiation from others, as indicated by a shallower PPS slope at Session 1 that correlated positively with negative symptoms. However, at Session 3, patients marked their bodily boundary in a steeper way, suggesting a sharper demarcation of PPS boundaries after the action with the tool. CONCLUSIONS: These findings highlight the importance of investigating the multisensory and motor roots of self-disorders, paving the way for future body-centred rehabilitation interventions that could improve patients' altered body boundary.