Theory of mind impairments in patients with deficit schizophrenia.

The deficit syndrome, a subgroup within schizophrenia, is characterized by enduring, idiopathic negative symptoms. Theory of mind (ToM), a domain of social cognition, is the ability of attributing mental states to ourselves and other people. ToM impairments have not been investigated earlier in deficit schizophrenia. The aim of the present study was to examine ToM differences between patients with deficit (SZ-D) and non-deficit schizophrenia (SZ-ND). Gender differences were also investigated, and based on the literature a better ToM performance was expected in female patients. The participants were 28 patients with SZ-ND, 30 patients with SZ-D, and 29 healthy control volunteers. The "Reading the Mind in the Eyes Test" was used to asses ToM deficits. Control subjects outperformed both patient groups, while there were no significant differences between the two schizophrenia subgroups. In female subjects, both controls and patients with SZ-ND performed significantly better than the SZ-D subgroup. In male subjects, controls performed significantly better than both patient groups. The "diminished emotional range" and the "curbing of interest" items of the Schedule for the Deficit Syndrome showed significant negative relationship with the ToM score. Our main finding is that female subjects with SZ-ND performed significantly better than female subjects with SZ-D.