Disconnected and underproductive speech in schizophrenia: unique relationships across multiple indicators of social functioning.

BACKGROUND: Cognitive deficits and communication abnormalities are central features of schizophrenia. Although cognition is a robust predictor of adaptive functioning, recent evidence suggests that communication abnormalities better predict social functioning.
METHODS: In 90 community-dwelling individuals with schizophrenia, we examined the contribution of two subtypes of communication disorder (disconnected speech and verbal underproductivity) to three interrelated but independent domains of social functioning: performance-based social competence, observer-rated social behavior, and self-reported quality of life (QOL). Using stepwise regression analyses, we examined the predictive value of disconnected speech and verbal underproductivity while simultaneously considering neurocognitive, clinical, and course of illness variables.
RESULTS: Regression analyses demonstrated robust relationships of communication abnormalities with measures of social functioning even when accounting for neurocognition, clinical symptoms, and course of illness. When examining real-world behavior, observer-rated social behavior was predicted by verbal underproductivity, whereas socially acceptable behavior was predicted by neurocognition and disconnected speech. Greater impairment in self-reported social quality of life was predicted by verbal underproductivity and neurocognition. Furthermore, there was an apparent differential deficit in the two scenes of the performance-based social competence task as a function of communication abnormality symptom (i.e., disconnected and verbally underproductive speech).
CONCLUSION: Discrete communication abnormalities are differentially associated with specific social competencies and behaviors; as such, they may be considered treatment targets to improve social functioning.