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

ABSTRACT

Data on clustering and switching during semantic fluency (SF) in patients with first-episode psychosis (PwFEP) are scant. We aimed to investigate (1) clustering and switching on SF in PwFEP using more detailed clustering analyses and (2) the possibility of disproportionate clustering deficits across different SF tasks in PwFEP and healthy subjects (HS), with the latter being suggested by the current literature on patients with schizophrenia. We recruited 22 Croatian-speaking PwFEP with schizophrenia features or symptoms and 22 HS matched in age, sex distribution, and handedness. All patients were medicated and had a mean illness duration of 1 month. The categories animals, trees, vegetables, fruits, and musical instruments were administered for SF. 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. Our results further suggest that PwFEP might show normal clustering performance on some SF tasks. We discuss the results in the context of the hypothesis of semantic hyperactivation in psychoses.

KEYWORDS:

• Semantic fluency
• schizophrenia
• first-episode psychosis
• clustering
• hypernymy
• semantic memory

Acknowledgments

We thank Ninoslav Mimica and Aleksandar Savić from the University Psychiatric Hospital ‘Vrapče’ of the University of Zagreb for making this research possible, allowing us to work with patients at the Hospital, as well as their generous insight. We further thank them for their assistance in data collection, data analyses, and interpretations relating to psychiatric practice. We also thank Vlasta Erdeljac and Martina Sekulić Sović from the Department of Linguistics of the University of Zagreb for inviting us and encouraging us to work on these data.

Disclosure Statement

The authors report no conflict of interest.

Notes

¹ Is added because the subcategory which is accessed first can never be a switch (because there is no preceding subcategory), but it can be a cluster.

Additional information

Funding

This work was supported by the Faculty of Humanities and Social Sciences of the University of Zagreb under Grant 11-831-1006.