Project 3: Prevention or treatment of vision or hearing impairments

Sensory impairments, including hearing and vision loss, affect up to 40% of older adults and have been linked to higher risk of Alzheimer’s disease and Alzheimer’s disease related dementias (AD/ADRD). Identification and treatment (or corrections) of hearing and vision impairment could be a high-impact strategy for AD/ADRD prevention, yet uncertainty remains about whether these strategies are likely to deliver true benefits. Large and diverse longitudinal studies offer advantages over intervention trials to understanding the long-term impacts of sensory impairment and their treatments on population-level AD/ADRD burden. However, estimating causal effects of sensory impairment and treatments using observational data requires sophisticated methods to address potential bias from confounding, reverse causation, selection bias, and measurement error. Furthermore, the effect of sensory impairment on AD/ADRD may be modified by other risk factors including sex/gender, race/ethnicity, socioeconomic status, genetic risk, and cardiovascular comorbidities. Understanding heterogeneity by social strata is essential to anticipate the potential impacts of interventions of sensory impairment on reducing AD/ADRD inequities. Few prior studies have implemented such methods or comprehensively evaluated heterogeneity by population subgroups. Our overarching goal is to rigorously evaluate the influence of sensory impairment and treatment of sensory impairments on AD/ADRD risk using modern causal inference methods and a data triangulation framework, which is a process of integrating evidence from multiple study designs and settings. Our secondary objective is to leverage multiple data sources to evaluate heterogeneity of effects in diverse populations and whether sensory impairments contribute to social inequities in AD/ADRD incidence. We will leverage 3 diverse longitudinal cohort studies complemented by other large-scale samples with integrated health care and genetic information to conduct our specific aims. Following our data triangulation framework, we will estimate whether hearing impairments and vision impairments increase risk of AD/ADRD (Aim 1) and whether treatment of impairments in hearing (hearing aid use) or vision (cataract surgery) reduces risk of AD/ADRD (Aim 2). Under Aim 3, we will examine heterogeneity (effect modification by other AD/ADRD risk factors (social factors, genetic risk, cardiovascular risk factors) in the estimated effects obtained in Aim 1 and 2. Finally, we will quantify reductions in AD/ADRD social inequities that could be achieved through prevention or treatment of hearing or vision impairments. The integration of this project within the TIMEAD program, our team’s expertise in cognitive aging, sensory impairment epidemiology, and the use of the proposed methods and data sources will uniquely enable us to accomplish our aims. This study’s findings will provide critical insight into whether prevention or treatment of hearing and vision impairment should be high priorities in efforts to reduce AD/ADRD incidence and inequities.