PROJECT SUMMARY/ABSTRACT The public health burden of Alzheimer's disease and related dementias (AD/ADRD) continues to increase as the American population ages. We are becoming increasingly aware of myriad physical and emotional needs confronted by people with dementia and their informal caregivers (unpaid family and friends) particularly at end of life (EOL). Most persons with AD/ADRD in the U.S. die in long-term care (LTC) communities, and assisted living (AL), as the fastest growing LTC option in the U.S., is a primary provider of this care. AL is a social model of care and in most states does not provide 24-hour skilled nursing care; most care is provided by unlicensed direct care workers with little or no healthcare training. Therefore, residents' informal caregivers play a critical role in supplementing this care. Their involvement ranges from social visits to more intensive types of informal care provision, including hands-on-care and monitoring and managing care that AL staff and other formal care providers (e.g., hospice) provide. What effect such involvement has on the health of informal caregivers and their care recipients over time is unknown. Limited empirical evidence from cross-sectional and retrospective research shows that greater informal caregiver involvement, particularly involvement that is more labor intensive and emotionally taxing, is associated with higher caregiver burden and suggests that this burden may be greater for informal caregivers in AL compared with other LTC settings, particularly in the context of caring for residents with advanced dementia at EOL. Some studies show that lower informal caregiver involvement is associated with lower resident quality of life of residents but these relationships have not been investigated in AL in depth or over time and the direction of these effects is unclear. To address these critical knowledge gaps, we propose a prospective longitudinal multilevel study that will follow 280 residents diagnosed with advanced AD/ADRD (6 or higher on the 7-stage dementia scale) for 12 months and assess the caregiving experiences of residents' primary informal caregivers (n=280). We will select residents and their informal caregivers from a stratified random sample of 45 assisted living communities in Georgia. The overall goal of this 5-year study is to improve understanding of the relationships between and among informal caregiver involvement, informal caregiver health (e.g., perceived physical and mental health, caregiver burden, and distress), and quality of life of assisted living residents with advanced dementia at EOL and to identify potentially modifiable factors at multiple socioecological levels (individual, AL, and wider community-level) associated with adverse outcomes. The proposed study supports the National Alzheimer's plan and its mission to improve care and support of persons with AD/ADRD and their caregivers. It will address significant knowledge gaps that will advance science an...