PROJECT SUMMARY ABSTRACT Age-related hearing loss (ARHL) results from the cumulative effects of aging on the auditory system. There is growing evidence linking ARHL with cognitive impairment and increased risk of Alzheimer’s disease and related dementias. In fact, the 2017 Lancet Commission for Dementia Prevention, Intervention and Care found that hearing loss is associated with the highest relative risk of dementia (RR 1.9) among 9 potentially modifiable risk factors. It is hypothesized that poor peripheral encoding of sound due to ARHL contributes to cognitive impairment by increasing cortical resources to auditory decoding from memory and other cognitive domains. Research shows an association between the severity of hearing loss and disability in activities of daily living, including shopping, preparing meals and household chores. Older adults with ARHL become socially isolated as communication problems increase, resulting in emotional and cognitive difficulties. The goal of this study is to understand the effect of cochlear implants and hearing aids using real-world data documenting daily performance in study subjects’ natural environments as a predictor of cognitive impairment, or progression from mild cognitive impairment to dementia in people with ARHL. Six groups of individuals, 65+ years of age, will be studied: 1) cochlear implant (Implant) users with normal cognition; 2) Implant candidates who naturalistically retained hearing aids (HA retainers) with normal cognition; 3) Implant users with mild cognitive impairment (MCI); 4) HA retainers with MCI; 5) normal hearing/normal cognition; and 6) normal hearing with MCI. Data from a smartphone ecological momentary assessment (EMA) system is this study’s primary outcome measure, including patient-reported outcomes collected in real-time across multiple domains: 1) listening environment; 2) hearing-related function; 3) hearing loss-related mental health; and 4) cognitive function. Aim 1. Compare the cross-sectional association of Implants or HAs on real-world EMA outcomes in ARHL with normal cognition. Hypothesis: Implants will be associated with better EMA outcomes (auditory function, cognitive performance, social interaction, psychosocial wellbeing) as compared to HA retainers. Aim 2. Compare the longitudinal effects of the use of Implants or HAs in AHRL with and without cognitive impairment on cognitive function, using real-world EMA outcomes and a neuropsychological battery. Hypothesis: Implants will be associated with better cognitive performance and less cognitive decline than HA retainers as measured by both EMA cognitive items and by neuropsychological testing in those with baseline ARHL-related MCI. Aim 3. Deploy study data in our visual analytics platform for precision medicine, clinical decision-support, and data-sharing of hearing/cognitive outcomes by 1) identifying predictor variables, 2) developing individualized predictive models for Implants/HAs, and 3) enabling large sc...