The language profile of formal thought disorder

Abstract

Formal thought disorder (FTD) is clinically manifested as disorganized speech, but there have been only few investigations of its linguistic properties. We examined how disturbance of thought may relate to the referential function of language as expressed in the use of noun phrases (NPs) and the complexity of sentence structures. We used a comic strip description task to elicit language samples from 30 participants with schizophrenia (SZ), 15 with moderate or severe FTD (SZ + FTD), and 15 minimal or no FTD (SZ−FTD), as well as 15 first-degree relatives of people with SZ (FDRs) and 15 neurotypical controls (NC). We predicted that anomalies in the normal referential use of NPs, sub-divided into definite and indefinite NPs, would identify FTD; and also that FTD would also be linked to reduced linguistic complexity as specifically measured by the number of embedded clauses and of grammatical dependents. Participants with SZ + FTD produced more referential anomalies than NC and produced the fewest definite NPs, while FDRs produced the most and thus also differed from NC. When referential anomalies were classed according to the NP type in which they occurred, the SZ + FTD group produced more anomalies in definite NPs than NC. Syntactic errors did not distinguish groups, but the SZ + FTD group exhibited significantly less syntactic complexity than non-SZ groups. Exploratory regression analyses suggested that production of definite NPs distinguished the two SZ groups. These results demonstrate that FTD can be identified in specific grammatical patterns which provide new targets for detection, intervention, and neurobiological studies.

The maturation of speech structure in psychosis is resistant to formal education

“…32 This is in agreement with the fact that schizophrenia subjects with formal thought disorder speak with more referential anomalies and less syntactic complexity than healthy controls. 33 Please note that the use of LSC as a proxy of syntactic complexity does not necessarily correspond to its definition in linguistics as the number of embedded clauses or dependents. Future investigation shall elucidate the precise relationship between graph-theoretical and linguistic measures in the discourse of subjects with psychosis, as well as the psychosis-related differences in the use of syntactic vs. semantic words (i.e., functional words such as possessive and relative pronouns, articles, and determiners, versus referential/content words such as nouns).…”

Acute conceptual disorganization in untreated first-episode psychosis: A combined magnetic resonance spectroscopy and diffusion imaging study of the cingulum

“…We chose this cut-off to distinguish those who have clinically severe versus minimal symptoms recommended by the Remission Working Group 31 . This cut-off has also been recently employed to distinguish patients with or without formal thought disorder and language dysfunction 32 . These two groups were not different in their severity of other positive and negative symptoms ( Table 1).…”

Language in schizophrenia and aphasia: the relationship with non-verbal cognition and thought disorder

“…It has been argued that thought in humans is intrinsically linguistic (Hinzen, Rosselló, & McKenna, 2016) and that linguistic abnormalities play a causal role in the development of FTD and delusions (Hinzen & Rosselló, 2015). These include loss of the referent in noun phrases, reduced syntactic complexity, including fewer clausal combinations, a lack of clausal embedding, and reduced figurative language (Çokal et al, 2018;Fraser, King, Thomas, & Kendell, 1986;Oh et al, 2002;Sevilla et al, 2018;Titone, Libben, Niman, Ranbom, & Levy, 2007). The apparent association of the origin of schizophrenia with the evolution of human language has been cited as providing further support for the pathogenic salience of language impairments (Crow, 2008;Palaniyappan et al, 2013).…”