The language profile of formal thought disorder

�okal, Derya; Sevilla, Gabriel; Jones, William Stephen; Zimmerer, Vitor; Deamer, Felicity; Douglas, Maggie; Spencer, Helen; Turkington, Douglas; Ferrier, Nicol; Varley, Rosemary; Watson, Stuart; Hinzen, Wolfram

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.

• Journal Article Type: Article
• Acceptance Date: Nov 8, 2018
• Online Publication Date: Sep 19, 2018
• Publication Date: 2018-12
• Deposit Date: Sep 21, 2021
• Publicly Available Date: Sep 22, 2021
• Journal: npj Schizophrenia
• Print ISSN: 2334-265X
• Electronic ISSN: 2334-265X
• Publisher: Nature Research
• Peer Reviewed: Peer Reviewed
• Volume: 4
• Issue: 1
• Article Number: 18
• DOI: https://doi.org/10.1038/s41537-018-0061-9
• Keywords: Psychiatry and Mental health
• Public URL: https://uwe-repository.worktribe.com/output/7816068
• Additional Information: Received: 24 March 2018; Revised: 5 August 2018; Accepted: 21 August 2018; First Online: 19 September 2018; : The authors declare no competing interests.