Theory of mind and language comprehension in schizophrenia: Poor mindreading affects figurative language comprehension beyond intelligence deficits

Patients suffering from schizophrenia have been found to be impaired in their pragmatic abilities in the comprehension of figurative language (e.g., metaphors, ironies, proverbs). Impairments in theory of mind (ToM; that is, the ability to attribute/infer mental states) have been proposed to be underlying high level language understanding. Even though ToM has been shown to be defective in schizophrenia, there is little information about the pattern of relations between ToM and language comprehension (LC) abilities. Our aim in this study is to explore how deficits in ToM concern the LC capacity in schizophrenia when general intelligence is controlled for. A total of 22 Spanish-speaking inpatients and 22 healthy controls matched in age, sex, education and language dominance were assessed using 3 ToM tasks and 6 LC tasks (covering lexical, syntactic, and semantic–pragmatic language processing levels) in order to establish to what extent ToM gets associated with LC abilities. Correlational analysis showed a connection between impairments in ToM and difficulties in LC. A discriminant function analysis showed that the variables that best discriminate between patients and controls are those corresponding to ToM-critical items and figurative LC tasks. Impairments in ToM seem to be mainly associated to LC in the semantic–pragmatic processing level and this association appears to be genuine, non dependent on IQ. In schizophrenia, mindreading impairments contribute negatively to the process of understanding figurative meanings beyond the presence of an impoverished intelligence.

from the Journal of Neurolinguistics