THEORY OF MIND AND PSYCHOSES

Background. A cardinal feature of schizophrenia is the sufferer's diff iculty in interacting appropriately within the social milieu. This def icit has recently been associated with the concept of theory of mind, more commonly construed as a working model to understand behavioural p atterns in autistic children. In this paper the complex relationships between theory of mind, IQ and psychoses are addressed. Methods. Five experimental groups were used; non-psychiatric controls, affective dis order, schizophrenia with normal pre-morbid IQ, schizophrenia with pre -morbid IQ in the mildly learning disabled range, and mild learning di sability with no history of psychiatric illness. All subjects were giv en a first order Theory of Mind Task and if successful, a second order Theory of Mind Task was then administered. All subjects were rated us ing the Positive and Negative Symptom Scale (PANSS). Results. Subjects with schizophrenia and subjects with mild learning disability show im paired ability on a second order theory of mind task. However, when pa tients who are unable to answer reality questions are removed from the analysis specific impairment of theory of mind is only seen in subjec ts with schizophrenia. Furthermore, this impairment is relatively spec ific to particular psychopathological clusters in subjects with schizo phrenia. Even though the same clusters of psychopathology are also see n in patients with affective disorder, their presence is not associate d with poor second order theory of mind performance. Conclusions. Impa ired theory of mind on second order tests is specific to schizophrenia when compared to mild learning disability and affective disorder cont rol groups. Subjects with schizophrenia and pre-morbid mild learning d isability show greater impairment than subjects with schizophrenia and a pre-morbid IQ within the normal range.