PROJECT SUMMARY This administrative supplement aims to reduce unnecessary or inappropriate care in older adults with Alzheimer’s disease and related dementias (AD/ADRD), using breast cancer over-screening as a case study. Mammography screening may decrease breast cancer mortality and morbidity, but the potential benefits are often delayed for many years while significant harms can occur in the short term. The harms of routine screening outweigh the benefits among older women with limited life expectancies, but many of these women, including those with AD/ADRD, continue to be screened. The parent project (R01AG066741) is studying the novel use of messaging interventions to reduce over-screening in the general population but does not focus on older women with AD/ADRD. Breast cancer screening decisions in AD/ADRD patients may differ in process (e.g., caregiver involvement), decisional factors, and communication. We propose in this supplement to examine whether the messaging strategies developed in the parent grant will be acceptable and effective for older women with AD/ADRD and their caregivers. The supplement also builds upon the parent project to examine AD/ADRD patients and caregivers’ decision-making about stopping breast cancer screening, which can serve as a case study to provide key insights on the de-implementation of other unnecessary or inappropriate preventive care where short-term harms outweigh delayed benefits. We propose to examine the perspectives of older women with AD/ADRD and their caregivers, including how they make breast cancer screening decisions and consider de-implementation, and feedback on the messaging strategies for reducing breast cancer over-screening from the parent project. We will conduct qualitative interviews of 15-20 older women with AD/ADRD and 15-20 caregivers (Aim 1) and quantitative survey of 400 caregivers for older women with AD/ADRD recruited from a nationally representative online panel (Aim 2). Lastly, we will leverage stakeholder engagement that is already planned in the parent project for devising messaging strategies. We propose to add stakeholders relevant to AD/ADRD patients and to expand discussion to de-implementation of breast cancer over-screening in patients with AD/ADRD. The proposed supplement will 1) enhance the parent project by ensuring that the developed messaging strategies are applicable to older women with AD/ADRD, and 2) provide key preliminary data on other intervention approaches for de-implementing breast cancer over-screening and other unnecessary or inappropriate care in older adults with AD/ADRD.