Theory of mind in schizophrenia: The role of clinical symptomatology and neurocognition in understanding other people's thoughts and intentions

A wealth of studies has demonstrated that patients with schizophrenia are impaired in "theory of mind" (ToM). Here, we used a novel five-factor model of the Positive and Negative Syndrome Scale (PANSS) to test the hypothesis that selectivity of ToM deficits in schizophrenia depends on the predominating symptoms. We predicted that ToM impairments would be non-selective in patients with pronounced negative (NF) or disorganized symptoms (DF), whereas selective ToM impairment would occur in patients with predominant positive symptoms (PF). We recruited 50 patients diagnosed with schizophrenia or schizoaffective disorder and examined premorbid intelligence, executive functioning, ToM and psychopathology in comparison to a group of 29 healthy controls. Compared with healthy controls, patients performed more poorly on tasks involving executive functioning and ToM abilities. Using a novel PANSS five-factor model, we found a significant association of ToM deficits with the "disorganization" factor. Moreover, several individual PANSS items that were included within the disorganization factor correlated with impaired ToM, albeit the majority of correlations disappeared when controlled for executive functioning, and, to a lesser degree, when controlled for IQ. In addition, in the patient group we found interactions of poor ToM with symptoms belonging to the "emotional distress" factor of the PANSS. Contrary to expectations, associations of impaired ToM with positive symptoms were absent, and poor with regards to negative symptoms. This study lends further support to the assumption of differential associations of ToM deficits with individual symptoms and symptom clusters in schizophrenia.