Introduction: Our objective was to examine the association between perseverations produced on the semantic verbal fluency (SVF) task in asymptomatic individuals and the future diagnosis of cognitive impairment (CI).
Method: Participants were individuals participating in the Mayo Clinic Study of Aging (N = 1269, Mage = 79.3 years, SD = 5.1; 51% men). All were cognitively normal at baseline and were followed in 15-month intervals for up to 6 visits. Each neurocognitive assessment included SVF tasks ("animals," "fruits," and "vegetables"). Cox modeling was used to test for associations between perseverations and time to CI diagnosis.
Results: Perseverations on the "animals" SVF task were associated with incident CI (hazard ratio = 1.35; 95% confidence interval, CI [1.10, 1.66]). No significant association was found with perseverations on the "fruits" or "vegetables" SVF tasks. Mixed-effects modeling in cognitively normal participants revealed that the number of perseverations at baseline is significantly associated with decline in memory and visuospatial cognitive domains but is not associated with decline in attention.
Conclusions: Assessing perseverations together with standard SVF scores on the "animals" SVF task can help in early identification of asymptomatic individuals at an increased risk for CI. Perseverations are not associated with attention, but rather visual and verbal working memory mechanisms. In longitudinal settings aimed at early detection of signs of CI in presymptomatic individuals, SVF testing with scoring that includes counting of perseverations may potentially serve as a practical alternative to the more cumbersome memory tests.
Keywords: Alzheimer’s disease; cognitive impairment; dementia; perseverations; verbal fluency.