Automated lexical analysis of interviews with individuals with schizophrenia

Schizophrenia is a chronic mental disorder that contributes to poor function and quality of life. We are aiming to design objective assessment tools of schizophrenia. In earlier work, we investigated non-verbal quantitative cues for this purpose. In this paper, we explore linguistic cues, extracted from interviews with patients with schizophrenia and healthy control subjects, conducted by trained psychologists. Specifically, we analyzed the interviews of 47 patients and 24 healthy age-matched control subjects. We applied automated speech recognition and linguistic tools to capture the linguistic categories of emotional and psychological states. Based on those linguistic categories, we applied a binary classifier to distinguish patients from matched control subjects, leading to a classification accuracy of about 86% (by leave-one-out cross-validation); this result seems to suggest that patients with schizophrenia tend to talk about different topics and use different words. We provided an in-depth discussion of the most salient lexical features, which may provide some insights into the linguistic alterations in patients.NRF (Natl Research Foundation, S’pore)NMRC (Natl Medical Research Council, S’pore)Accepted versio

Some markers of mirroring appear intact in schizophrenia: evidence from mu suppression

Although schizophrenia is associated with impairments in social cognition, the scope and neural correlates of these disturbances are largely unknown. In this study, we investigated whether schizophrenia patients show impaired functioning of the mirror neuron system (MNS), as indexed by electroencephalographic (EEG) mu (8-13 Hz) suppression, a hypothesized biomarker of MNS activity that is sensitive to the degree of social interaction depicted in visual stimuli. A total of 32 outpatients and 26 healthy controls completed an EEG paradigm that included six action observation or execution conditions that differed in their degrees of social interaction. Participants also completed a validated empathy questionnaire. Across both groups, we found a significant linear increase in mu suppression across the conditions involving greater levels of social engagement and interaction, but no significant group or interaction effects. Patients self-reported diminished empathic concern and perspective taking, which showed some moderate relations to mu suppression levels. Thus, the schizophrenia group showed generally intact modulation of MNS functioning at the electrophysiological level, despite self-reporting empathic disturbances. The disturbances commonly seen on self-report, performance, and neuroimaging measures of mentalizing in schizophrenia may largely reflect difficulties with higher-level inferential processes about others' emotions, rather than a basic incapacity to share in these experiences