Effects of social cognitive impairment on speech disorder in schizophrenia.

Disordered speech in schizophrenia impairs social functioning because it impedes communication with others. Treatment approaches targeting this symptom have been limited by an incomplete understanding of its causes. This study examined the process underpinnings of speech disorder, assessed in terms of communication failure. Contributions of impairments in 2 social cognitive abilities, emotion perception and theory of mind (ToM), to speech disorder were assessed in 63 patients with schizophrenia or schizoaffective disorder and 21 nonpsychiatric participants, after controlling for the effects of verbal intelligence and impairments in basic language-related neurocognitive abilities. After removal of the effects of the neurocognitive variables, impairments in emotion perception and ToM each explained additional variance in speech disorder in the patients but not the controls. The neurocognitive and social cognitive variables, taken together, explained 51% of the variance in speech disorder in the patients. Schizophrenic disordered speech may be less a concomitant of "positive" psychotic process than of illness-related limitations in neurocognitive and social cognitive functioning.