Pragmatic and executive dysfunction in schizophrenia

Many studies have reported that patients with schizophrenia (SZ) can be impaired in their pragmatic abilities, typically affecting the processing of non-literal speech acts (e.g., metaphors, indirect requests). Various hypotheses have been proposed to account for impairments in understanding non-literal language, such as executive dysfunction or problems attributing mental states to others; the latter is referred to as theory of mind (ToM) abilities. The aim of this study was to explore whether pragmatic deficits do or do not coexist with ToM impairments and/or impairments of executive functions in schizophrenia. Twenty SZ patients and twenty matched healthy control (HC) participants - all right-handed and native French-speakers - were tested individually for three abilities: (a) pragmatic, (b) ToM (original first- and second-order mental state attribution tasks) and (c) executive functions. The main results showed that SZ patients exhibit pragmatic impairments which co-occurred with an executive dysfunction such as a lack of flexibility and a ToM deficit. Subsequent analyses of covariance suggested that ToM could play a role in pragmatic understanding while flexibility did not. Our study gives partial support to neuroimaging literature showing an impaired involvement of the prefrontal cortex in such processing in schizophrenia.