S55. PRAGMATIC INFERENCES IN SCHIZOPHRENIA: RELATIONSHIP WITH SYMPTOM DOMAINS, THEORY OF MIND AND NEUROCOGNITIVE FUNCTIONS

BACKGROUND: Severe impairment in interpersonal functioning is a common feature of schizophrenia. Deficits in communicative abilities are likely to be among the important factors contributing to social dysfunction in schizophrenia. Difficulties in pragmatic language abilities including understanding intended meaning, beyond explicit and literal content of conversational statements can significantly hamper interpersonal and occupational functioning. An important aspect of pragmatic inference is the ability to derive scalar implicatures (SIs), which are based on linguistic expressions like some, or, often etc. For deriving SIs, one need to go beyond simple semantic and logical level. To date, only a single study has investigated SIs in schizophrenia (Wampers et al 2018). In this study, people with psychosis were less likely to derive SIs than controls. A preliminary analysis of 17 patients with schizophrenia in the same study also showed that better ToM was associated with a higher ability to derive SIs Importantly, the association with schizophrenia and abnormalities in pragmatic infererence might be mediated by clinical features of this illness including formal thought disorder and negative symptoms. Also, difficulties in pragmatic inferences might potentially be secondary to neurocognitive dysfunction rather than being primary deficits. No previous study has investigated clinical and neurocognitive correlates of impairment in ability to derive SIs in schizophrenia. METHODS: The study included 79 patients with schizophrenia-spectrum disorders (66 schizophrenia and 13 schizoaffective disorder) and 49 healthy controls who completed a SI task. SAPS, SANS were also administered. Comprehension of irony, metaphor and faux pas were assessed using verbal story tasks. A subgroup of patients were also administered a comprehensive neuropsychological battery and two ToM tasks (Hinting task and RMET (Reading the Mind from the Eyes). RESULTS: There were no significant group difference between schizophrenia and healthy controls for age (F=0.69, p=0.41) and gender (Chi square=2.2, p=0.13). The schizophrenia sample had a shorter duration of education compared to the healthy controls (F=27.2, p<0.001). The patients with schizophrenia had significant impairment in understanding the SIs (F=8.2, p=0.005). Comprension impairment of SIs were significantly associated with SANS negative symptoms (r=-0.29, p= 0.009) but not with SAPS positive formal thought disorder (r=-0.09, p=0.44) and symptoms ratings for hallucinations and delusions. Understanding SIs in schizophrenia was significantly related to better performance in RMET (r=0.34, p=0.036) and irony comprehension (r=-0.38, p=0.001). DISCUSSION: Schizophrenia is associated with significant deficits in understanding pragmatic utterances. These deficits were significantly related to some aspects of social cognition but not neurocognition. Current findings do not support the proposed relationship between formal thought disorder and pragmatic abnormalities in schizophrenia. These findings might have implications in management of social functioning deficits in schizophrenia.