Idea density in the life-stories of people with schizophrenia: Associations with narrative qualities and psychiatric symptoms

Disordered speech and language deficits are well-documented in schizophrenia-spectrum disorders. Researchers often assess speech samples using manualized rating systems, though recently computerized language assessment methods have been used more frequently in the study of speech from people with schizophrenia. Most typically, these computerized assessments measure aspects of expressivity (i.e., pause durations, prosody) or use word-count technology; less attention has focused on similar methods that can capture more sophisticated aspects of linguistic complexity (e.g., idea density). The primary objective of the present study was to assess idea density - via a computerized measure - in the life-story narratives of people with schizophrenia (n = 32) compared to a group of community control participants (n = 15). In the schizophrenia group, we also examined associations between idea density, narrative qualities rated via a manualized measure, and psychiatric symptoms. Our findings indicate that idea density is diminished in individuals with schizophrenia compared to controls. Further, our results suggest that though people with schizophrenia with richer idea density tended to have more developed insight into illness, they also had higher levels of depression, anxiety, and avolition. Implications of these results and suggestions for future research are discussed.