Alzheimer?s disease and related dementias (AD/ADRD), age-related cognitive decline, stroke, and heart disease are pressing public health problems with high prevalence in racial/ethnic minority older adults. Building on our strong cross-sectional findings linking greenness exposure (vegetative presence) to lower rates of chronic diseases -- including AD, cardiometabolic indicators (diabetes, hypertension, hyperlipidemia), heart disease and stroke -- we propose to investigate neighborhood greenness exposure as a novel environmental protective factor for cognitive decline and vascular outcomes (stroke, myocardial infarction [MI] and vascular death). The proposed study will be the first to investigate prospectively and longitudinally: 1) the relationship of cumulative greenness exposure to cognitive performance and vascular outcomes; 2) the mediating roles of behavioral, cardiometabolic, novel inflammatory/infectious and novel vascular brain imaging biomarkers in the relationship of cumulative greenness exposure to cognitive performance and vascular outcomes; and, 3) for whom (individual moderators) and under what conditions (neighborhood moderators) greenness has its impact on cognitive performance and vascular outcomes. We will also examine 4) the longitudinal relationship of cumulative greenness exposure to brain reserve; and 5) the moderating effect of brain reserve in the relationship of greenness to cognitive resilience/performance. Finally, we will 6) explore in post-hoc analyses the relationship of cumulative greenness exposure to adjudicated MCI, AD and ADRD. This proposal builds on the Northern Manhattan Study (NOMAS), a prospective cohort that focuses on risk factors for stroke and cognitive decline in a multi-ethnic/multi-racial aging population. The study of cognitive performance trajectories will be conducted using cognitive performance assessments conducted at three time points (over 10 years minimum) in 1,290 NOMAS participants (with magnetic resonance imaging at baseline). The study of vascular outcomes will include all 3,298 NOMAS participants over ~14 years. Mediating pathways include: 1. Behavioral measures (physical activity; social support); 2. cardiometabolic biomarkers (blood pressure; fasting glucose; BMI; waist circumference); 3. novel inflammatory biomarkers (IL6, TNFR1); and, 4. novel vascular brain imaging biomarkers (white matter hyper-intensity volume, silent brain infarction, cortical thickness). Moderators (for whom and under what conditions) include age, race/ethnicity, sex, education and APOE status, neighborhood income, walkability and crime. Several factors enable us to efficiently and cost-effectively conduct the study, including the rich array of NOMAS data in a diverse sample; availability of archived data on built, natural and social environmental factors for NYC; collaboration of NOMAS study PIs and co-investigators to facilitate smooth data access; and an established and experienced interdisciplinary team of architects and urban planners, biostatisticians, cognitive psychologists, epidemiologists and environmental public health scientists, geographers, and neurologists.