Theory of mind (ToM) deficit is a potential trait marker of schizophrenia, based on an assessment of patients with the disorder and their unaffected siblings.

A family-based control design study of 41 patients with first-episode schizophrenia, 43 unaffected siblings, and 42 healthy controls revealed that patients and unaffected siblings both exhibit ToM impairment vs the control group. However, there was no dissociation between affective and cognitive component.

The siblings performed better than patients but worse than controls on the Faux Pas Task. Meanwhile, patients performed worse than controls on the Yoni Task, whereas their siblings did not.

ToM impairment had previously been consistently demonstrated in individuals with schizophrenia, but the its presence in unaffected siblings was poorly studied. These results support the notion of using ToM as a trait marker of schizophrenia.

Citation: Ho K, Hung K, Wang Y, et al. Theory of mind impairments in patients with first-episode schizophrenia and their unaffected siblings. Schizophr Res. 2015; 166:1-8.