A – 93 Cognitive Variability, Global Cognitive Functioning, and Verbal Fluency Change in Cognitively Normal Older Adults

Abstract Objective This study examined the relationship between intra-individual variability (IIV), overall cognitive performance, and verbal fluency change in cognitively normal older adults. Method 186 participants (M = 72.95 years old, SD = 5.92; 61.3% Female; 81.7% White, 15.6% African American) from the Harvard Aging Brain Study (HABS) completed the Boston Naming Test, Category Fluency Test, Controlled Oral Word Association Test (FAS), Digit Span Test, Digit Symbol Substitution Test, Letter Number Sequencing Test, Logical Memory I & II, and Trail Making Test: Parts A & B. IIV was measured using the coefficient of variation (CoV). CoV was calculated as overall test battery mean (OTBM) standard deviation divided by OTBM. Verbal fluency change was calculated as the difference between FAS total scores at time 1 data collection and time 6 data collection. Results Pearson correlations were used to evaluate the relation between CoV, OTBM, and change in verbal fluency over time. OTBM was negatively correlated with CoV (r = -.323; p = < .001) and verbal fluency change (r = -.154; p = .036). There was not a significant association between CoV and verbal fluency change, nor between OTBM and OTBM SD. Conclusion Higher overall cognitive performance was associated with more cognitive consistency and less decline in verbal fluency over time. However, CoV was not significantly related to longitudinal change in verbal fluency. While prior research suggests that cognitive inconsistency may be a useful biomarker of neuropathology in clinical populations, additional research is needed to explore the underlying mechanisms contributing to cognitive variability in cognitively normal individuals.