Clustering and switching analysis of verb fluency in individuals with Alzheimer's disease.
Bárbara Costa Beber, Franceia Veiga Liedtke, Felipe Schroeder de Oliveira and 4 others
PMID 37075412WHAT IT FOUND
Older adults with Alzheimer's disease named fewer action words and shifted between groups of related verbs less often than healthy adults.
The size and number of verb groups did not differ.
Key findings
01After age and education were controlled, the Alzheimer's disease group produced an estimated mean of 7.0 verbs, compared with 9.6 in controls, and made an estimated mean of 3.9 switches, compared with 5.5 in controls.
02Number of clusters and average cluster size did not differ significantly: estimated mean clusters were 2.4 in controls and 2.1 in the Alzheimer's disease group, and estimated mean cluster size was 1.6 and 1.5.
03The mild Alzheimer's disease subgroup (n=18) and moderate subgroup (n=11) did not differ significantly on any verb fluency outcome.
STILL TO COME
How it was doneWhat they foundWhat it means for SLPs
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What it does not show
The final analyzed sample was 68 of an initial 102 participants, because some had missing data or could not understand the task instructions. The analyzed Alzheimer's disease and control groups differed in age and education despite the stated matching, so the comparison relied on statistical adjustment. The study compared groups at one time point, so it cannot show that verb fluency changes cause Alzheimer's disease or track progression. The mild and moderate Alzheimer's disease subgroups were small, with 18 and 11 participants, and no verb fluency outcome reached significance, so the study cannot rule out a severity effect. Cluster and switch scoring included errors and repetitions, and the verb categories were developed by the research team, which may make comparison with standard fluency scoring difficult. The supplied text did not include a funding or conflict-of-interest declaration.
The easy way to misread this
Do not conclude that verb fluency is a diagnostic test for Alzheimer's disease or that it can distinguish mild from moderate disease. The study compared groups at one time point, and the mild and moderate subgroups did not differ significantly on any verb fluency outcome.