Deficit in the ability to understand others' mental conditions, opinions, beliefs, fantasies and desires have been reported among schizophrenic patients so far. However, fewer studies have examined the type of positive/negative symptoms and delusions on their social cognition abilities. The main purpose of this study was to investigate the theory of mind (ToM) performance in schizophrenic patients and compare it with healthy controls.

This cross-sectional study conducted at Ibn-e-Sina psychiatric hospital in Mashhad, included 28 schizophrenic patients, aged between 18 and 50, based on DSM-IV-TR criteria and 14 healthy subjects. Evaluation of symptoms was performed by positive and negative syndrome scale (PANSS) test and the ToM assessed by the 'Reading the Mind in the Eyes” Test.

Analysis of variance showed a significant impaired ToM in schizophrenic patients as compared with the healthy controls (p=0.00). But the ToM deficits did not differ in positive and negative symptoms (p=0.951), genders (p=0.286) and the frequency of episodes (p= 0.470). The delusions of persecution and grandeur showed a significant lower ToM performance as compared with the delusions of control (p=0.041).

Although the ToM abilities impairment in schizophrenia has been proved, its relationship with types of symptoms and delusions, and the duration of illness require further investigations. This may help to improve the possible treatments and prevention potentials in future.