Background: Vision impairment (VI) is associated with incident cognitive decline and dementia. However, it is not known whether VI is associated only with the transition to cognitive impairment, or whether it is also associated with later transitions to dementia.
Methods: We used data from the population-based Aging, Demographics and Memory Study (ADAMS) to investigate the association of visual acuity impairment (VI; defined as binocular presenting visual acuity <20/40) with transitions from cognitively normal to cognitive impairment no dementia (CIND) and from CIND to dementia. Multivariable Cox proportional hazards models and logistic regression were used to model the association of VI with cognitive transitions, adjusted for covariates.
Results: There were 351 participants included in this study (weighted percentages: 45% male, 64% age 70-79 years) with a mean follow-up time of 4.1 years. In a multivariable model, the hazard of dementia was elevated among those with VI (hazard ratio = 1.63, 95% confidence interval = 1.04-2.58). Participants with VI had a greater hazard of transitioning from cognitively normal to CIND (hazard ratio = 1.86, 95% confidence interval = 1.09-3.18). However, among those with CIND and VI a similar percentage transitioned to dementia (48%) and remained CIND (52%); there was no significant association between VI and transitioning from CIND to dementia (hazard ratio = 0.94, 95% confidence interval = 0.56-1.55). Using logistic regression models, the same associations between VI and cognitive transitions were identified.
Conclusions: Poor vision is associated with the development of CIND. The association of VI and dementia appears to be due to the higher risk of dementia among individuals with CIND. Findings may inform the design of future interventional studies.
Keywords: Blindness; Cognitive transitions; Epidemiology; Health and Retirement Study.
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