Exploring Verbal Fluency Strategies among Individuals with Normal Cognition, Amnestic and Non-Amnestic Mild Cognitive Impairment, and Alzheimer's Disease

Styliani Bairami; Vasiliki Folia; Ioannis Liampas; Eva Ntanasi; Panayiotis Patrikelis; Vasileios Siokas; Mary Yannakoulia; Paraskevi Sakka; Georgios Hadjigeorgiou; Nikolaos Scarmeas; Efthimios Dardiotis; Mary H Kosmidis

doi:10.3390/medicina59101860

Exploring Verbal Fluency Strategies among Individuals with Normal Cognition, Amnestic and Non-Amnestic Mild Cognitive Impairment, and Alzheimer's Disease

Medicina (Kaunas). 2023 Oct 19;59(10):1860. doi: 10.3390/medicina59101860.

Authors

Affiliations

¹ Lab of Cognitive Neuroscience, School of Psychology, Aristotle University of Thessaloniki, University Campus, 54124 Thessaloniki, Greece.
² Department of Neurology, University Hospital of Larissa, School of Medicine, University of Thessaly, Mezourlo Hill, 41110 Larissa, Greece.
³ Department of Nutrition and Dietetics, Harokopio University, 70 El. Venizelou, 17671 Athens, Greece.
⁴ 1st Department of Neurology, Aiginition Hospital, National and Kapodistrian University of Athens Medical School, Vassilissis Sofias Ave 72, 11528 Athens, Greece.
⁵ Athens Alzheimer's Association, 89 M. Mousourou & 33 Stilponos St, 11636 Athens, Greece.
⁶ School of Medicine, University of Cyprus, 93 Agiou Nikolaou St, Engomi, Nicosia 2408, Cyprus.
⁷ Taub Institute for Research in Alzheimer's Disease and the Aging Brain, The Gertrude H. Sergievsky Center, Department of Neurology, Columbia University, 710 West 168th St, New York, NY 10032, USA.

Abstract

Background and Objectives: The present study explored the utilization of verbal fluency (VF) cognitive strategies, including clustering, switching, intrusions, and perseverations, within both semantic (SVF) and phonemic (PVF) conditions, across a continuum of neurocognitive decline, spanning from normal cognitive ageing (NC) to mild cognitive impairment (MCI) and its subtypes, amnestic (aMCI) and non-amnestic (naMCI), as well as AD. Materials and Methods: The study sample was derived from the Hellenic Longitudinal Investigation of Aging and Diet (HELIAD) cohort. The sample included 1607 NC individuals, 146 with aMCI (46 single-domain and 100 multi-domain), 92 with naMCI (41 single-domain and 51 multi-domain), and 79 with AD. Statistical analyses, adjusting for sex, age, and education, employed multivariate general linear models to probe differences among these groups. Results: Results showed that AD patients exhibited poorer performance in switching in both VF tasks and SVF clustering compared to NC. Similarly, the aMCI group performed worse than the NC in switching and clustering in both tasks, with aMCI performing similarly to AD, except for SVF switching. In contrast, the naMCI subgroup performed similarly to those with NC across most strategies, surpassing AD patients. Notably, the aMCI subgroup's poor performance in SVF switching was mainly due to the subpar performance of the multi-domain aMCI subgroup. This subgroup was outperformed in switching in both VF tasks by the single-domain naMCI, who also performed better than the multi-domain naMCI in SVF switching. No significant differences emerged in terms of perseverations and intrusions. Conclusions: Overall, these findings suggest a continuum of declining switching ability in the SVF task, with NC surpassing both aMCI and AD, and aMCI outperforming those with AD. The challenges in SVF switching suggest executive function impairment associated with multi-domain MCI, particularly driven by the multi-domain aMCI.

Keywords: amnestic MCI; clustering; continuum of neurocognitive decline; intrusions; mild cognitive impairment; non-amnestic MCI; perseverations; switching; verbal fluency strategies.

MeSH terms

Alzheimer Disease* / complications
Cognition
Cognitive Dysfunction*
Executive Function
Humans
Neuropsychological Tests

Grants and funding

This work was supported by the following grants: IIRG-09-133014 from the Alzheimer’s Association; 189 10276/8/9/2011 from the ESPA-EU program Excellence Grant (ARISTEIA), which is co-funded by the European Social Fund and Greek National resources, and DY2b/oik.51657/14.4.2009 from the Ministry for Health and Social Solidarity (Greece). The funders had no role in the design, analysis, or writing of this article.