Persons with Alzheimer’s disease (AD) and AD-related dementia (AD/ADRD) are vulnerable to heat-illness, particularly in socioeconomically disadvantaged neighborhoods, due to limited resources to combat heat exposure. High temperature is a risk factor for acute ischemic stroke (AIS), and is associated with worse stroke morbidity and mortality. The problem is that both environmental heat and socioeconomic stressors independently impact persons with AD/ADRD and also are associated with worse stroke outcomes. Yet, no extant studies have evaluated the combined impact of environmental heat and socioeconomic stressors (i.e., heat vulnerability) on stroke outcomes in persons with AD/ADRD. The objective of this proposal is to evaluate the role of the heat vulnerability index (HVI) on stroke functional outcomes in persons with AD/ADRD. HVI was developed by the New York State and City Departments of Health as a combined metric integrating environmental and socioeconomic factors to identify neighborhoods with higher risk of heat-related deaths. We hypothesize that persons with AD/ADRD in high-HVI neighborhoods suffer higher rates of AIS, worse stroke severity (National Institutes of Health Stroke Scale - NIHSS≥6, Alberta Stroke Program Early CT Score - ASPECTS<6), and worse outcomes on discharge with higher mortality (modified Rankin scale - mRS6), dependent disability (mRS3-5), and new-onset oropharyngeal dysphagia. The rationale is based on our preliminary data, which shows significantly higher AIS rates in high-HVI, compared to low-HVI neighborhoods. In this proposal, we will establish the AD/ADRD and AIS rates and trends in high- and low-HVI neighborhoods over the past decade from 2014-2023 (Aim 1); and we will compare AIS rates (Aim 2), stroke severity (Aim 3), and stroke outcomes (Aim 4) between high- and low-HVI neighborhoods in patients with AD/ADRD. Since HVI has not been evaluated in prior AD/ADRD studies, we will analyze the most comprehensive and diverse database from New York State's largest health system, with the following advantages relevant to this proposal: 1) Large sample size of >1,100,000 hospitalized patients, >80,000 patients with AD/ADRD, and >25,000 AIS events. 2) Broad racial and ethnic diversity for robust evaluation of socioeconomic disparities in the AD/ADRD and AIS populations. 3) Over 200 unique, relevant clinical variables (that do not exist in state or nationwide claims data) for patients with AD/ADRD and AIS that will advance studying health inequities in the AD/ADRD population. Our proposal is highly significant because we aim to uncover the link between environmental heat, socioeconomic disparities, and stroke outcomes in AD/ADRD that can drive meaningful change in the following ways: a) Discover a novel stroke risk factor to provide new targets for intervention that will improve functional outcomes in persons with AD/ADRD. b) Identify specific neighborhoods with health inequities to implement preventative strategies that ...