Abstract
BackgroundImpaired social functioning is one of the most apparent features of psychotic disorders. Deficits in social cognition may explain impaired functioning even more than the other cognitive deficits related to psychosis. Of the areas of social cognition, especially relevant to psychosis appear to be deficiencies in theory of mind (ToM), the ability to perceive and interpret the mental states of others, or “mentalizing”. Currently, it is unclear to what extent general cognitive deficits explain impairment in ToM.We wanted to explore 1) the possible difference in ToM between first-episode psychosis (FEP) patients and controls, 2) whether diagnosis group (schizophrenia vs. other psychotic disorders) and level of functioning are associated with ToM, and 3) to what extent these differences are explained by general cognitive performance.MethodsThis study examined ToM in young adults with FEP (n=66). Of those, 25 had schizophrenia and the rest were diagnosed with other psychotic disorders. Age- and gender-matched controls were identified from the Population Information System (n=62). The participants were administered a broad neuropsychological assessment, part of which was the Hinting Task assessing ToM. With 10 short discussions in everyday situations, the Hinting Task assesses the ability to conclude, from indirect speech, what another person really means.A factor score of the Hinting Task was formed, taking into account the varying difficulty level and relevance of the 10 items. To investigate the association between ToM and general cognitive functions, we summarized non-social cognitive performance constructing a “g factor”, which was used as an overall index of general cognitive performance.ResultsThe internal consistency of the Hinting Task calculated from the dichotomized data was modest, with McDonald’s categorical omega estimated at .57 (95 % CI .36, .71). In the single dimensional factor solution, items 8 and 9 had the weakest loadings and item 10 the strongest. Items 9 and 10 of the Hinting Task were the easiest, and items 1 and 8 were the most difficult.Participants with FEP (mean score 16.0) performed worse than controls (mean score 17.4) on the Hinting Task (Cohen’s d=0.50 calculated from factor scores). However, the difference between FEP and control groups was no longer significant when general cognition was controlled for. 75 % of the variance between the groups was explained by general cognitive deficits, especially impaired processing speed (WAIS-III Digit Symbol) and episodic memory (WMS-III Logical Memory).When the FEP group was divided according to diagnosis, those with schizophrenia scored lower on the Hinting Task than the other psychosis patients. The ToM difference between individuals with schizophrenia and controls (Cohen’s d=1.1) remained significant even when general cognitive performance was controlled for. In contrast, those with other psychotic disorders than schizophrenia did not differ from controls.ToM performance of the best functioning patient group (20 patients who had a GAF score ≥50, Hinting Task mean score 17.8) did not differ from that of the control group.DiscussionBased on this study, and supporting previous findings (Bora & Pantelis, Schizophr. Res. 2013), deficits in ToM were already present in early psychosis. They were largely overlapping with deficits in general cognitive processes. However, and in line with previous meta-analytical findings (Sprong et al., Br. J. Psychiatry 2007), in a subgroup of the FEP patients with schizophrenia, impairments in ToM remained after controlling for overall cognitive functioning. In conclusion, specific deficits in ToM could be found in schizophrenia, independent from general cognitive deficits.
Highlights
Social cognition can be defined as perception and interpretation of and responding to other people’s thoughts and actions
The current study found that in a subgroup of the first-episode psychosis (FEP) patients with schizophrenia, specific impairments are present on the Hinting Task, independent from general cognitive deficits
It should be noted that theory of mind (ToM) performance was heterogeneous in the whole FEP group, with a large portion of the FEP group having no deficits in ToM, as measured with the Hinting Task
Summary
Social cognition can be defined as perception and interpretation of and responding to other people’s thoughts and actions. ToM can be defined as the ability to understand the mental states of others (Green et al, 2008). In order to comprehend the way the other people act, one has to observe their point of view and – based on social cues and context – make assumptions of their mental states. This ―mentalizing‖ enables prediction and understanding of other people’s actions. Social functioning in the community may rely on intact social cognition or ToM
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