PROJECT SUMMARY/ABSTRACT Loneliness and social isolation are related, but distinct, social risk factors critical to the health and quality of life of older adults in their last years of life. Loneliness is a subjective feeling of being alone, whereas social isolation is an objective loss in the number of relationships with family, friends, or the community. Both social risk factors are common and independently associated with poor health outcomes relevant to late life such as depression, functional impairment, and mortality. Very little is known, however, about loneliness and social isolation among the general population of older adults in the last years of life, particularly those with cognitive impairment or Alzheimer’s Disease and Related Dementia. Unfortunately, older adults with and without Alzheimer’s Disease and Related Dementia may be particularly vulnerable to loneliness and social isolation and their effects in the last years of life. While the last years of life have an intense focus on medical care, less recognized social factors like loneliness may be more important to patients, especially for persons with cognitive impairment or Alzheimer’s Disease and Related Dementia. The objective of this study is to establish the epidemiology of loneliness and social isolation in the last years of life among older adults with and without cognitive impairment or Alzheimer’s Disease and Related Dementia and determine their association with intensive health care use at the end of life. We hypothesize that loneliness and social isolation are a common source of suffering among older adults in their last years and associated with worse quality end-of-life health care, especially for those with cognitive impairment or Alzheimer’s Disease and Related Dementia. To test this hypothesis, the following aims are proposed: Aim 1) Determine the prevalence and predictors of loneliness and social isolation during the last four years of life among older adults with and without cognitive impairment or Alzheimer’s Disease and Related Dementia using a nationally-representative cohort; Aim 2) Determine the relationship between loneliness and social isolation with potentially burdensome healthcare at the end of life for those with and without cognitive impairment or Alzheimer’s Disease and Related Dementia; and Aim 3) Develop an in-depth understanding of the experience of loneliness, social isolation, and potentially burdensome healthcare among older adults with cognitive impairment or Alzheimer’s Disease and Related Dementia using qualitative interviews. This proposal will have a significant impact in characterizing a substantial source of suffering among older adults with and without Alzheimer’s Disease and Related Dementia in the crucial end of life period and potential intervention strategies. I will obtain advanced training in observational and health services research, qualitative analysis, implementation sciences, and clinical writing, along with mentorship fro...