Cohort Differences in Cognitive Impairment and Cognitive Decline among Mexican-Americans Aged 75 Years or Older

Research suggests that the prevalence and incidence of cognitive impairment among older adults is decreasing. This analysis used data from 9 waves (1993-2016) of the Hispanic Established Populations for the Epidemiologic Study of the Elderly to assess cognitive status and cognitive decline for 2 cohorts of Mexican-Americans aged ≥75 years in 1993-1994 versus 2004-2005. Logistic regression, joint longitudinal survival models, and illness-death models for interval-censored data were used to examine cohort differences in the odds of prevalent cognitive impairment, trajectories of cognitive decline, and the risk of 10-year incident cognitive impairment, respectively. Results indicated that compared with the 1993-1994 cohort, the 2004-2005 cohort had higher odds for prevalent cognitive impairment (odds ratio = 2.51, 95% confidence interval (CI): 1.92, 3.29), particularly among participants with <4 years of education (odds ratio = 2.99, 95% CI: 2.14, 4.18). Conversely, the 2004-2005 cohort exhibited significantly slower rates of cognitive decline (β = 0.50, 95% CI: 0.39, 0.62) and had a significantly lower risk of incident cognitive impairment (hazard ratio = 0.75, 95% CI: 0.62, 0.91) compared with the 1993-1994 cohort. This analysis provides mixed results for cohort trends in the cognitive health of older Mexican-Americans. Continued research is needed to identify risk factors that contribute to these population-level trends.