Semantic fluency reveals reduced functional connectivity between subcategorical co-hyponyms in recent-onset inpatients with first-episode psychosis

Abstract

In the wake of limited knowledge on clustering and switching during semantic fluency (SF) in patients with first-episode psychosis (PwFEP), the present study aimed (1) to investigate clustering and switching on SF in PwFEP using more precise statistical procedures and (2) to investigate the possibility of disproportionate clustering patterns across different SF tasks in PwFEP and healthy subjects (HS), as this has been indicated by the current literature on patients with schizophrenia. We recruited 22 PwFEP and 22 HS matched in age, sex distribution, and handedness. All patients were medicated and had a mean illness duration of 1 month (median: 0). Five categories were administered for SF: animals, trees, vegetables, fruits, and musical instruments (60 seconds each). PwFEP produced significantly fewer correct words in the aggregate score, as well as across all categories. The switching rate was significantly higher in PwFEP, but no post hoc comparisons were significant. PwFEP also produced significantly smaller clusters, yet the post hoc comparisons for the tree and fruit task were not significant. A higher switching rate and smaller clusters indicate less efficient functional connectivity within subcategories of the given categories, but not necessarily between the subcategories. Although both less likely to produce a cluster once a switch has been uttered and less likely to produce clusters larger than two words compared to HS, the latter deficit was more pronounced. Possibly, PwFEP might have greater difficulty in processing more concrete compared to more abstract concepts. Finally, our results also indicate that there are category-specific effects on the clustering deficit in PwFEP, possibly demonstrating that PwFEP might show normal performance on executively more demanding SF subtasks. We discuss the results in the context of the hypothesis of semantic hyperactivation in schizophrenia.

Spoken Word Segmentation in First and Second Language: When ERP and Behavioral Measures Diverge

“…On the other hand, this apparent language dominance imbalance might also be caused by the different letters and categories used in the English and French versions of the verbal fluency task. Research has suggested that speakers tend to produce more tokens overall in the "animals" category than in the "fruits" category (Moreno-Martínez et al, 2017;Gabrić and Vandek, 2020). Thus, the apparent language proficiency imbalance in favor of English might be caused by our use of an "easier" category in the testing of English proficiency.…”

Performance on verbal fluency tasks depends on the given category/letter: Preliminary data from a multivariable analysis

“…Discrepancies were discussed until mutual agreement was achieved. Clustering and switching variables were calculated according to Gabrić and Vandek (2021a).…”

“…It is clear from studies reporting descriptive data of multiple SF tasks that there are stark discrepancies in the number of legal words produced by healthy subjects across different semantic categories. Typically, adult healthy subjects produce the most words on animal fluency, while productivity on other semantic categories may be reduced by more than twofold (Bosanac et al, 2017; Gabrić & Vandek, 2021a; Jebahi et al 2020, 2021; Kim et al, 2015; Moreno-Martínez et al, 2017; Vicente et al, 2021). For example, Jebahi et al (2020) reported that subjects produced 18 words on average on animal fluency but less than ten on the categories accessories, tools, transportation means, furniture , and sports .…”

“…Ferrett et al, 2014). Gabrić and Vandek (2021a) reported that inpatients with first-episode psychosis displayed deficient clustering on the categories animals, vegetables , and musical instruments but not on trees and fruits , while Tagini et al (2021) reported that patients with Parkinson’s disease showed semantically disorganized output on the category fruits but not animals .…”

“…One study on SF in Alzheimer’s disease has revealed that the extent of the deficit is dependent on the given category’s size (Diaz et al, 2004), while Moreno-Martínez et al (2017) and Neves et al (2020) found that although the animal fluency is by far the most commonly utilized SF task for research on dementia, other categories such as supermarket items, fruits , and vegetables are more sensitive in distinguishing healthy people from patients with dementia. Gabrić and Vandek (2021a) reported that inpatients with first-episode psychosis displayed deficient clustering on the categories animals, vegetables , and musical instruments but not on trees and fruits , despite the presence of a normative deficit in productivity across all categories, while Tagini et al (2021) reported that patients with Parkinson’s disease showed semantically disorganized output on the category fruits but not animals .…”