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Clustering and switching on verbal fluency tests in Alzheimer's and Parkinson's disease

Published online by Cambridge University Press:  02 April 2001

Angela K. Troyer
Affiliation:
Rotman Research Institute of Baycrest Geriatric Centre; University of Toronto, Toronto, ON, Canada
Morris Moscovitch
Affiliation:
Rotman Research Institute of Baycrest Geriatric Centre; University of Toronto, Toronto, ON, Canada Department of Psychology, Baycrest Geriatric Centre, Toronto, ON, Canada Erindale College, Mississauga, ON, Canada
Gordon Winocur
Affiliation:
Rotman Research Institute of Baycrest Geriatric Centre; University of Toronto, Toronto, ON, Canada Trent University, Peterborough, ON, Canada
Larry Leach
Affiliation:
Department of Psychology, Baycrest Geriatric Centre, Toronto, ON, Canada
and Morris Freedman
Affiliation:
Rotman Research Institute of Baycrest Geriatric Centre; University of Toronto, Toronto, ON, Canada Behavioral Neurology Program, Baycrest Geriatric Centre; Department of Medicine (Division of Neurology), Mount Sinai Hospital and University of Toronto, Toronto, ON, Canada

Abstract

Two components of verbal fluency performance—clustering (i.e., generating words within subcategories) and switching (i.e., shifting between subcategories)—were examined in patients with dementia of the Alzheimer type (DAT), patients with dementia with Parkinson's disease (DPD), nondemented patients with Parkinson's disease (NPD), and demographically matched controls. The DAT and DPD groups were impaired in the number of words generated on both phonemic and semantic fluency. The DAT group produced smaller clusters on both tasks and switched less often on semantic fluency than controls. The DPD group switched less often on both tasks and produced smaller clusters on phonemic fluency than controls. The NPD group was not impaired on any fluency variable. Thus, the total number of words generated on phonemic and semantic fluency did not discriminate the dementia groups from their respective control groups, but measures of clustering and switching did. This differential pattern of performance provides evidence for the potential usefulness of measures of switching and clustering in the assessment of dementia. (JINS, 1998, 4, 137–143.)

Type
Research Article
Copyright
© 1998 The International Neuropsychological Society

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Footnotes

Reprint requests to: A. Troyer, Rotman Research Institute, Baycrest Centre for Geriatric Care, 3560 Bathurst Street, Toronto, ON M6A 2E1, Canada. E-mail: a.troyer@utoronto.ca.