Individual differences in cognitive plasticity and variability as predictors of cognitive function in older adults




Grand, Jacob Harold Gross

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Background: With the growth in elderly populations worldwide, there is a pressing need to characterize the changes in cognition and brain function across the adult lifespan. The evolution of cognitive abilities is no longer considered to reflect a universal, cumulative process of decline. Rather, significant inter- and intra-individual differences exist in cognitive trajectories, with the maintenance of functions ultimately determined by multi-dimensional biological and psychological processes. The current study examined the relationship between intra-individual variability, cognitive plasticity, and long-term cognitive function in older adults. Methods: Data were analyzed from Project Mental Inconsistency in Normals & Dementia (MIND), a 6-year longitudinal burst design study, integrating micro-weekly assessments (reaction time (RT) tasks), with macro-annual evaluations (cognitive outcome measures). Participants included 304 community-dwelling adults, ranging in age from 64 to 92 years (M = 74.02, SD = 5.95). Hierarchical multiple regression models were developed to examine long-term cognitive function, along with multilevel modeling (HLM) techniques for the analysis of specific predictors of longitudinal rates of cognitive change. Results: Baseline intraindividual variability (ISD) emerged as a robust and highly sensitive predictor, with increased variability associated with decreased long-term cognitive performance. Complex baseline cognitive plasticity (1-Back 4-Choice RT Task) uniquely predicted subsequent cognitive function for measures of processing speed, fluid reasoning, episodic memory, and crystallized verbal ability. Multilevel models revealed chronological age to be a significant predictor across cognitive domains, while intraindividual variability selectively predicted rates of change for performance on measures of episodic memory and crystallized verbal ability. Conclusion: These findings underscore the potential utility of intraindividual variability and cognitive plasticity as dynamic predictors of longitudinal change in older adults.



older people, cognitive, reasoning, memory