Stability in cognitive function over 18 years: Prevalence and predictors among older Mexican Americans

Purpose: Numerous studies have examined the association of physical, behavioral and social factors with cognitive decline in older adults. Less attention has been placed on factors associated with long-term maintenance of intact cognition even into very old age. A greater understanding of those factors can inform the development of activities for maintaining cognitive strength. Methods: Using a sample from the Hispanic Established Populations for Epidemiologic Study of the Elderly, a population-based study of non-institutionalized Mexican Americans aged 65 and older from five Southwestern states (N =2767), latent class mixture models were developed to identify subgroups of cognitive change over time. Results: Three distinct trajectories of cognitive change were identified and characterized as stable, slow decline and rapid decline. Compared to the rapid decline group, a higher proportion of the stable cognition group were women, had high school education, were married and attended church one or more times per week. Regular church attendance had a significant positive impact in the stable group (β = 0.64, p <0.01), the slow decline group (β = 0.84, p <0.001) and the rapid decline group (β= 2.50, p <0.001). Activity limitations had a consistently negative association with cognition in the stable, slow decline and rapid decline groups (β = -0.37, p <0.001; β = -0.85, p <0.001; and β = -1.58, p <0.001 respectively). Conclusion: Substantial heterogeneity exists in rates of cognitive decline among older Mexican Americans. Interventions targeting cognitive maintenance may benefit from increased focus on factors associated with continued social engagement.