Formal thought disorder (FTD) or thought disorder (TD) is clinically manifested as disorganized speech. Eugen Bleuler (1857-1939), who gave his name to schizophrenia, upheld that thought disorder was its defining feature. However, there are few behavioural studies on the linguistic features presented by this cognitive disorder. There is evidence of a strong association between the deterioration of language and cognitive deterioration in FTD, and some authors have argued that all types of schizophrenia are intrinsically related to language.

Two recent studies of 2018, published in Nature Schizophrenia and PLOS One, respectively, both directed by  Wolfram Hinzen, ICREA research professor with the Department of Translation and Language Sciences (DTCL), with the participation of Gabriel Sevilla, a member of the Grammar and Cognition Laboratory and a student of the PhD in Translation and Language Sciences at UPF, have researched the linguistic patterns of schizophrenia.

In the papers published in Nature Schizophrenia and in PLOS One, the authors have examined how FTD is related to language

Language disorders hinder linguistic communication affecting not only linguistic aspects (semantics, syntax, comprehension and expression), but also intellectual aspects. Previous studies have documented a reduction in syntactic complexity and an increase in syntactic errors in patients with schizophrenia. In the papers published in Nature Schizophrenia and in PLOS One, the authors have examined how FTD is related to language and have studied how this disorder is expressed in the use of nominal phrases or sentences, as well as in the complexity of the structures that make up a grammatical sentence.

In the study published in Nature Schizophrenia, the researchers designed a controlled clinical trial in which 30 people diagnosed with schizophrenia performed a language task that involved describing a comic strip. Of these, 15 individuals also had moderate or severe FTD, and in the other 15, the disorder was minimal or absent. The trial also involved 15 first-degree relatives of the patients with schizophrenia and 15 neurotypical individuals who acted as a control group. In the study published in PLOS One they studied the narrative discourse of 40 patients with schizophrenia, 20 of whom also had FTD, and 14 healthy subjects who acted as a control group.

The patients with schizophrenia and FTD produced more referential anomalies than the individuals in the control group and fewer definite nominal phrases. Although syntax errors do not in themselves distinguish the groups, they showed that in people with schizophrenia and FTD, syntactic complexity was lower than that displayed by the group with schizophrenia without FTD.

The results of these studies indicate that thought disorder exhibits a specific and differentiated linguistic profile.

Identifying these specific grammatical patterns in people with FTD provides new targets for the detection, intervention and study of neurobiological disorders such as schizophrenia

Added to cognitive and neuroimaging studies, the linguistic profile of patients with schizophrenia could be included in its diagnosis and prognosis and might be a linguistic marker for the progression of the disease. In the same way, the important role of language for diagnosis and prognosis could be extended to other cognitive disorders, including autism spectrum disorders, depression, Huntington’s disease or Alzheimer’s disease, the authors of this study suggest.

Reference works:

Derya Çokal, Gabriel Sevilla, William Stephen Jones, Vitor Zimmerer, Felicity Deamer, Maggie Douglas, Helen Spencer, Douglas Turkington, Nicol Ferrier , Rosemary Varley , Stuart Watson, Wolfram Hinzen (2018), “The language profile of formal thought disorder”, npj Schizophrenia 4:18 ; doi:10.1038/s41537-018-0061-9.

Gabriel Sevilla, Joana Rosselló, Raymond Salvador, Salvador Sarró, Laura López-Araquistain, Edith Pomarol-Clotet, Wolfram Hinzen (2018), “Deficits in nominal reference identify thought disordered speech in a narrative production task”, PLOS One, https://doi.org/10.1371/journal.pone.0201545.

e-Repositori UPF

Sevilla G, Rosselló J, Salvador R, Sarró S, López-Araquistain L, Pomarol-Clotet E, Hinzen W. Deficits in nominal reference identify thought disordered speech in a narrative production task. PLoS ONE. 2018; 13(8): e0201545. DOI: 10.1371/journal.pone.0201545