Objective and Subjective Clustering Methods for Verb Fluency Responses From Individuals With Alzheimer's Dementia and Cognitively Healthy Older Adults.
Madison N Fisher, Devin M Casenhiser, Eun Jin Paek
PMID 37722380WHAT IT FOUND
People with Alzheimer's dementia produced significantly fewer verbs and fewer switches between action categories than healthy adults, while cluster size did not differ.
An automated database matched human raters well enough to offer a replicable way to score verb fluency.
Key findings
01Individuals with Alzheimer's dementia produced significantly fewer total words, fewer clusters, and fewer switches than cognitively healthy older adults when using the objective clustering method.
02There was no significant difference between the groups regarding average cluster size.
03Interrater reliability for the subjective clustering method was variable, particularly for average cluster size, suggesting human coding can be inconsistent without strict criteria.
STILL TO COME
How it was doneWhat they foundWhat it means for SLPs
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What it does not show
Small sample size (42 participants total) limits generalizability. The subjective clustering method lacked strict, standardized criteria, leading to poor interrater reliability for key variables like cluster size. The study used a task-congruent clustering method only, so results may not apply to other ways of analyzing fluency data. The groups differed significantly in age, which could influence cognitive performance, although secondary analyses excluding outliers maintained the main results.
Declared interests
Research was supported by the National Institute on Aging (NIH Grant R03AG072236).
The easy way to misread this
Do not interpret the lack of difference in average cluster size as evidence that semantic memory is intact in Alzheimer's dementia. The study found significant deficits in total output and switching, suggesting that while the ability to group words may be preserved, the overall retrieval process and executive control are impaired.