Project Summary The last decade has brought spectacular growth in the number of people enrolled in the Medicare Advantage (MA) program, including those with Alzheimer's Disease and Related Dementias (ADRD). One potential but poorly understood challenge for MA enrollees is that unlike the traditional Medicare program, private insurers may cease offering services to beneficiaries. From 2011 to 2020, nearly one-fifth of all MA contracts terminated participating in the Medicare program. Terminations may be particularly disruptive to beneficiaries with ADRD who may struggle to identify an optimal plan that meets their needs from an often-bewildering set of choices. Terminations typically require switching to a MA plan with different benefits, out-of-pocket costs, physician networks, and medication formularies, or to the traditional Medicare program. To mitigate the potential negative consequences of contract terminations, the Medicare program has used default assignments to automatically switch low-income or dual-eligible beneficiaries to the traditional Medicare program and a randomly assigned Part D plan. Our preliminary work suggests that these default assignments have strong effects: dual-eligible beneficiaries in terminated contracts have markedly higher rates of switching to traditional Medicare compared with other enrollees. Little is known about the consequences of MA contract terminations and default assignments, particularly for people living with ADRD, a population with complex clinical and social needs. This mixed-methods project examines the effects of contract terminations on outcomes for MA enrollees with ADRD. We focus on those with ADRD given this population's substantial care needs, risk for adverse outcomes, and the cognitive burden required to make high-stakes and time-sensitive insurance decisions. Our central hypotheses are that: (1) MA contract terminations will have negative health consequences for beneficiaries with ADRD, and (2) these effects will be magnified for persons with ADRD who are forced to make an active insurance decision (or face the loss of drug coverage) compared to those automatically assigned to traditional Medicare and Part D coverage. Specific aims include: 1. examine the impact of contract terminations on acute hospitalizations and mortality among persons with ADRD; 2. determine the effect of enrollment in traditional Medicare vs specific types of MA plans following a termination event; and 3. characterize the consequences of contract terminations through interviews with key informants and engagement with an advisory panel including persons with ADRD and caregivers. We innovate by applying a regression-discontinuity design and leveraging Medicare's default assignments to draw causal inferences about the effects of enrollment in MA contracts vs. traditional Medicare for people with ADRD. By providing rigorous evidence about the impact of terminations for beneficiaries with ADRD, our study has the potential t...