Mental state attribution, neurocognitive functioning, and psychopathology: what predicts poor social competence in schizophrenia best?

BACKGROUND: Research into mental state attribution has repeatedly shown that patients with schizophrenia are impaired in their capacity to reflect upon their own and others' beliefs, knowledge and intentions, with important confounds being executive functioning, intelligence, duration of illness, and medication. Furthermore, the extent to which impaired mental state attribution, neurocognition and psychopathology explain abnormal social behavior in schizophrenic patients has been a matter of debate. We sought to determine whether mental state attribution in schizophrenia predicts poor social competence better than "non-social" cognitive factors or psychopathology.
METHODS: Intelligence, executive functioning, mental state attribution, psychopathology and social behavior were assessed in 38 patients diagnosed with schizophrenia according to DSM-IV criteria and compared with 29 healthy controls paralleled for age and sex. All patients received antipsychotic treatment, and all participants had no history of substance abuse or traumatic brain injury.
RESULTS: In the entire schizophrenia group impaired mental state attribution alone accounted for about 50% of the variance of deviant social behavior, whereas the PANSS positive score and the duration of illness contributed an additional small amount of variance. This effect was even more pronounced in a subgroup of patients with at least normal intelligence, where neither the PANSS score nor the chronicity of the disorder remained significant predictors of poor social competence. Medication was not associated with any one of the neurocognitive measures including mental state attribution, psychopathology or social behavior.
CONCLUSIONS: Impaired capacity to appreciate one's own and others' mental states is the single-best predictor of poor social competence in schizophrenia, and should perhaps be included in future definitions of the "core" symptomatology of schizophrenic disorders.