Characterizing the Paradoxical Interplay of Semantic Perseveration and Derailment in Psychiatry Using Theory-Driven...

Area of Science:

• Computational linguistics
• Psychiatric diagnostics
• Natural Language Processing (NLP)

Background:

• Formal thought disorder (FTD), marked by derailment and perseveration, is key in psychosis and present in other psychiatric conditions.
• Existing NLP metrics for FTD, like cosine distance, struggle to differentiate between derailment and perseveration due to their opposing effects.
• Novel NLP metrics are needed to specifically identify and quantify perseveration independently of speech disorganization.

Purpose of the Study:

• To develop and validate novel NLP metrics for accurately measuring perseveration in formal thought disorder.
• To differentiate the linguistic markers of perseveration from those of derailment using advanced NLP techniques.
• To assess the utility of these new metrics in a transdiagnostic sample and in relation to psychopathological dimensions.

Main Methods:

• Synthetic narrative data were generated using large language models, manipulating semantic perseveration and derailment independently.
• Novel density-based NLP metrics were developed, focusing on semantic structure and density via clustering and dimensionality reduction.
• The performance of novel metrics was compared against traditional cosine distance metrics on synthetic data and an 811-participant general population sample.

Main Results:

• Traditional cosine distance metrics effectively detected derailment but were less accurate for perseveration.
• Novel density-based metrics demonstrated superior performance in identifying and separating perseveration from derailment.
• Density metrics also outperformed traditional metrics in identifying perseveration linked to repetitive thinking, depressive symptoms, and negative FTD.

Conclusions:

• Integrating density-based NLP metrics with traditional semantic distance measures offers a more comprehensive approach to capturing FTD symptoms.
• This novel approach enhances the understanding of perseveration and its interplay with thought and speech disorganization.
• Further clinical validation is required, but these metrics hold potential for improved clinical assessment and understanding of FTD.