Dement Neurocogn Disord.  2019 Jun;18(2):47-61. 10.12779/dnd.2019.18.2.47.

Clustering and Switching Patterns in Semantic Fluency and Their Relationship to Working Memory in Mild Cognitive Impairment

• Oh SJ
• Sung JE
• Choi SJ
• Jeong JH

• KMID: 2451001
• DOI: http://doi.org/10.12779/dnd.2019.18.2.47

Abstract

BACKGROUND AND PURPOSE
Semantic verbal fluency test is a neuropsychological assessment that can sensitively detect neuropathological changes. Considering its multifactorial features tapping various cognitive domains such as semantic memory, executive function, and working memory, it is necessary to examine verbal fluency performance in association with underlying cognitive functions. The objective of the current study was to investigate semantic fluency patterns of people with mild cognitive impairment (MCI) based on clustering and switching and their relationship with working memory.
METHODS
Twenty-six individuals with MCI and 23 normal elderly adults participated in this study. A semantic verbal fluency test (animal version) was administered and the performance was analyzed using the following measures: number of correct words, cluster size, and number of switches. Scores of digit forward (DF) and backward span tasks were employed as working memory measures.
RESULTS
Analyses of variance revealed significant group differences in the numbers of correct words and switches. Multivariate logistic regression and receiver-operating characteristic analyses showed that the number of switches more sensitively distinguished MCI existence than the number of correct words. Stepwise linear regression analysis showed that DF task and age significantly predicted the number of correct words while only the DF task significantly predicted the number of switches.
CONCLUSIONS
Decrement in semantic verbal fluency in MCI seems to be associated with impaired switching abilities. Working memory capacity might serve as the underlying cognitive factor related to decreased verbal fluency in MCI.

Keyword

Mild Cognitive Impairment; Semantic Fluency; Clustering; Switching; Working Memory

MeSH Terms

Adult
Aged
Cluster Analysis*
Cognition
Executive Function
Humans
Linear Models
Logistic Models
Memory
Memory, Short-Term*
Mild Cognitive Impairment*
Semantics*

Figure

• 

  Fig. 1 Number of correct words, mean cluster size, and number of switches in MCI and normal elderly groups. MCI: mild cognitive impairment. *p<0.05; †p<0.01.

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  Fig. 2 ROC curves of number of correct words, number of switches, and K-MMSE for MCI. ROC: receiver-operating characteristic, AUC: area under the curve, K-MMSE: Korean-Mini Mental State Examination, MCI: mild cognitive impairment.

• 

  Fig. 3 Scatterplot for both groups (MCI and normal elderly) in number of correct words, mean cluster size, and number of switches. MCI: mild cognitive impairment, DF: digit forward, DB: digit backward.

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