Clustering and switching in semantic fluency: predictors of the development of Alzheimer's disease

Fagundo, Ana B.; López, Samuel Sacido; Romero, M Ortega; Guarch, Joana; Marcos, T.; Salamero, Manel

doi:10.1002/gps.2025

Cited by 55 publications

(57 citation statements)

References 24 publications

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“…Alzheimer disease (AD) is the main cause of dementia (World Alzheimer Report 2015). It has been previously reported that abnormal performance in this specific task was associated with the occurrence of AD (Fagundo et al 2008). Thus, we suggested that this cognitive task may be more difficult to perform while walking compared to counting backward in early stages of the disease that leads to greater gait variability.…”

Section: Discussionmentioning

confidence: 73%

Association of increased gait variability while dual tasking and cognitive decline: results from a prospective longitudinal cohort pilot study

et al. 2017

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Dual task-related changes in gait are considered as a sensitive and a specific marker of adverse effects of cognitive impairment on the highest levels of gait control. No study has examined the longitudinal association between gait performance while dual tasking and the occurrence of cognitive decline. This study aims to examine the association of stride time parameters (i.e., mean value and coefficient of variation (CoV)) during single and dual tasking with the occurrence of cognitive decline in non-demented older community dwellers. A total of 56 non-demented community dwellers were recruited in a longitudinal prospective cohort study. Mini-Mental Status Examination (MMSE) scores at baseline assessment and at 5-year follow-up assessment, and mean value and CoVof stride time at self-selected usual pace, while usual walking and dual tasking (i.e., counting backward and verbal fluency task) at baseline assessment were recorded. Variation (i.e., delta) of MMSE score from baseline to follow-up assessment as well as of stride time parameters from single to dual task was used as outcomes. Worse stride time values were reported while dual tasking compared to single tasking (P < 0.03). An increase of mean value, CoV, and delta of CoVof stride time was associated with an increased delta MMSE while performing verbal fluency task (P < 0.05). Worsening stride time parameters while performing a verbal fluency task at baseline assessment was associated with decline in MMSE score during the 5-year follow-up period in this sample of older community dwellers.

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Section: Discussionmentioning

confidence: 73%

Association of increased gait variability while dual tasking and cognitive decline: results from a prospective longitudinal cohort pilot study

et al. 2017

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“…Words produced during these tasks are the result of more than one underlying cognitive process, such as “clustering” (automatic activation of one concept by a related, activated concept, making it more probable that a subject will say, “Dog, cat”) and “switching” (a deliberate, goal-oriented change from one sub-category to another, e.g . “dog… seahorse”) (Abwender, Swan, Bowerman, & Connolly, 2001; Hirshorn & Thompson-Schill, 2006; Troyer & Moscovitch, 2006; Troyer, Moscovitch, Winocur, Alexander, & Stuss, 1998; Fagundo, Lopez, Romero, Guarch, Marcos, & Salamero, 2008; Pakhomov & Hemmy, 2013). These component processes are affected in MCI and may predict conversion to dementia (Fagundo, Lopez, Romero, Guarch, Marcos, & Salamero, 2008; Murphy, Rich, & Troyer, 2006; Clark, Gatz, Zheng, Chen, McCleary, & Mack, 2009; Price, et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

Latent information in fluency lists predicts functional decline in persons at risk for Alzheimer disease

Clark¹,

Kapur²,

Geldmacher³

et al. 2014

Cortex

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Objective We constructed random forest classifiers employing either the traditional method of scoring semantic fluency word lists or new methods. These classifiers were then compared in terms of their ability to diagnose Alzheimer disease (AD) or to prognosticate among individuals along the continuum from cognitively normal (CN) through mild cognitive impairment (MCI) to AD. Method Semantic fluency lists from 44 cognitively normal elderly individuals, 80 MCI patients, and 41 AD patients were transcribed into electronic text files and scored by four methods: traditional raw scores, clustering and switching scores, “generalized” versions of clustering and switching, and a method based on independent components analysis (ICA). Random forest classifiers based on raw scores were compared to “augmented” classifiers that incorporated newer scoring methods. Outcome variables included AD diagnosis at baseline, MCI conversion, increase in Clinical Dementia Rating-Sum of Boxes (CDR-SOB) score, or decrease in Financial Capacity Instrument (FCI) score. ROC curves were constructed for each classifier and the area under the curve (AUC) was calculated. We compared AUC between raw and augmented classifiers using Delong’s test and assessed validity and reliability of the augmented classifier. Results Augmented classifiers outperformed classifiers based on raw scores for the outcome measures AD diagnosis (AUC 0.97 vs. 0.95), MCI conversion (AUC 0.91 vs. 0.77), CDR-SOB increase (AUC 0.90 vs. 0.79), and FCI decrease (AUC 0.89 vs. 0.72). Measures of validity and stability over time support the use of the method. Conclusion Latent information in semantic fluency word lists is useful for predicting cognitive and functional decline among elderly individuals at increased risk for developing AD. Modern machine learning methods may incorporate latent information to enhance the diagnostic value of semantic fluency raw scores. These methods could yield information valuable for patient care and clinical trial design with a relatively small investment of time and money.

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“…This notion has been highlighted by studies showing that semantic fluency clustering is one of the best neuropsychological markers of focal regions affecting the temporal lobe (Troyer et al 1998). Clustering performance is also impaired in pathologies such as Alzheimer's disease, characterized by memory deficits and neurodegenerative damage to medial temporal structures (Fagundo et al, 2008;Pantel et al, 2004). Our results suggest, therefore, that the poorer semantic-based word fluency observed in ecstasy users (De Sola et al, 2008) can be explained in terms of a disorganization or a degradation of the semantic store, putatively associated with MDMA effects on hippocampus/temporal lobe functioning.…”

Section: Discussionmentioning

confidence: 96%

“…On semantic fluency, clusters were defined as groups of successively generated words that belonged to the same semantic subcategory, such as farm animals, pets, aquatic animals, African animals, and insects. The subcategories were determined a priori (Fagundo et al, 2008; for examples see also the Appendix). Cluster size was computed by adding up series of words from the same subcategory, starting from the second word within each cluster (i.e.…”

Section: Verbal Fluency Assessmentmentioning

confidence: 99%

“…Clustering relies on the integrity of semantic stores, whereas switching depends on flexibility skills needed to perform subcategory changes when necessary. A deeper analysis of these strategies has been useful in revealing the cognitive mechanisms underlying fluency deficits across different clinical populations, including schizophrenia (Bozikas et al, 2005;Sumiyoshi et al, 2005), Parkinson's disease (De Gaspari et al, 2006), Huntington disease (Ho et al, 2002;Troster et al, 1998), vascular dementia (Duft et al, 2004), focal brain lesions (Troyer et al, 1998), and Alzheimer's disease (Epker et al, 1999;Fagundo et al, 2008;Troster et al, 1998). In addition, these studies have contributed to the finding that clustering is associated with temporal lobe functioning (Troster et al, 1998;Troyer et al, 1998), while switching is mostly impaired among patients with left dorsolateral and superior medial frontal lobe lesions (Troyer et al, 1998) as well as in fronto-subcortical pathologies (Ho et al, 2002;Troster et al, 1998).…”

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confidence: 99%

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The influence of 5-HTT and COMT genotypes on verbal fluency in ecstasy users

et al. 2010

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Deficits in verbal fluency associated with ecstasy use have been well established; however, the mechanisms underlying this impairment have yet to be elucidated. In this study we investigated for the first time whether there was a disproportionate impairment in two cognitive subcomponents of verbal fluency: clustering (ability to generate words within the same subcategory) and switching (ability to change the subcategory). We also investigated a possible association between ecstasy use and verbal fluency in subjects genotyped for 5-HTT (5-HTTLPR and 5-HTTVNTR) and COMT (val(108/158)met, rs165599 and rs2097603) polymorphisms, in order to find a potential implication of genetic factors. Ecstasy polydrug users (n = 30) and non-ecstasy users (n = 41) were evaluated in both semantic and phonemic fluency. Results showed that ecstasy users had poorer semantic (but not phonemic) fluency performance than controls. Detailed analysis of clustering and switching performance revealed that this impairment was associated with poorer clustering mechanisms. Clustering was also modulated by the COMT rs165599 polymorphism independently of the group. A specific effect of the 5-HTTLPR polymorphism on switching performance was also found, with ss carriers performing significantly worse than ls and ll carriers, suggesting a serotonin modulation of frontal-executive flexibility. Based on the impaired clustering and switching strategies observed in ecstasy users, it might be proposed that both semantic knowledge and retrieval are impaired in this population. The verbal fluency deficit in ecstasy users may be attributable to a disruption of frontal-striatal circuits directly related with the serotonin function as well as a depletion of lexical-semantic stores mediated by temporal structures.

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Clustering and switching in semantic fluency: predictors of the development of Alzheimer's disease

Abstract: Subjects with memory complaints and AD patients have an alteration in both qualitative and quantitative aspects of semantic fluency. A clustering analysis could enhance the reliability of early AD diagnosis.

Cited by 55 publications

References 24 publications

Association of increased gait variability while dual tasking and cognitive decline: results from a prospective longitudinal cohort pilot study

Association of increased gait variability while dual tasking and cognitive decline: results from a prospective longitudinal cohort pilot study

Latent information in fluency lists predicts functional decline in persons at risk for Alzheimer disease

The influence of 5-HTT and COMT genotypes on verbal fluency in ecstasy users

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