Date of Award

January 2016

Document Type

Open Access Thesis

Degree Name

Medical Doctor (MD)

Department

Medicine

First Advisor

Philip Corlett

Second Advisor

Marc Potenza

Abstract

LANGUAGE IN SCHIZOPHRENIA: WHAT WE CAN LEARN FROM QUANTITATIVE TEXT ANALYSIS

Sasha Deutsch-Link, Sarah Fineberg, Philip R. Corlett. Department of Psychiatry, Yale University School of Medicine, New Haven, CT.

Background: People living with schizophrenia demonstrate broad language and communication deficits. Prior research has focused on qualitative changes in thought, speech production, and language comprehension. In this thesis I expand upon our understanding of language in schizophrenia, by using a novel, quantitative method for language analysis, Linguistic Inquiry Word Count (LIWC).

Methods: I examined essays by four groups of authors: people with schizophrenia (n=77), family history of schizophrenia (n=25), psychiatric controls (mood/anxiety, n=29), and non-psychiatric controls (college students, n=418). Essays were then processed using Linguistic Inquiry Word Count (LIWC), which organizes language into parts of speech and pre-defined content themes and then calculates percent word type used. I performed multiple ANOVAs to examine group differences followed by Tukey post-hoc and FDR correction for multiple variables. Standard of significance was determned at p < .05. Afterwards, I performed a cluster analysis using MClust in R to examine whether patients living with schizophrenia tended to cluster with people with a family history of schizophrenia.

Results: Mood disorder essays used more affective language and “I.” Essays written by patients with schizophrenia used more external referential language (“humans” and “religion”) and less “I” than controls. Family members used less “I” and more religion-related words than controls, but had similar reference to other humans. In function word use, schizophrenia and family member essays used more articles, and fewer pronouns than controls. Schizophrenia and family member essays also contained more perceptual language.

Conclusions: Important differences emerged between schizophrenia essays, family member essays and controls. Decreased “I” and increased external referential language likely reflect loss of agency/power in schizophrenia. Decreased pronoun use in schizophrenia and family members likely reveals a degree of social isolation or withdrawal. The cluster analysis demonstrated that family members clustered with the schizophrenia group, suggesting a possible intermediate language phenotype. These findings can be expanded upon in future studies by analyzing spoken and/or unedited speech, controlling for demographic variables, and by using more standardized essay prompts.

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