PROJECT SUMMARY An estimated 5.3 million Americans have Alzheimer's disease in 2015. 1 Barring scientific innovations, the number of Americans with Alzheimer's disease (AD) is expected to increase to over 7 million by 2025 and 13.8 million by 2050. 1 In 2013, the Centers for Medicare and Medicaid Services (CMS) established that amyloid PET scans would be covered under the CMS Coverage with Evidence policy, and the Imaging Dementia – Evidence for Amyloid Scanning (IDEAS) study was created. IDEAS examines how amyloid PET scans guide doctors in diagnosing AD and other dementias early in disease progression, where the cause is ambiguous. IDEAS recruitment of 18,500 Medicare beneficiaries began in March 2016, and supplemental studies expanding on the rich clinical imaging and medical report data were encouraged. The approved CARE IDEAS supplemental study introduces the voice of the patient and care partner through open-ended survey questions and standardized measures on decision making, preferences, cognitive status, and emotional well-being. CARE IDEAS baseline recruitment and data collection on 3,500 IDEAS patients and their care partners is ongoing [R56 AG053934, NIH/NIA]. This proposed R-01 project will collect follow-up surveys from all respondents at 24 months, linking repeated survey responses to amyloid PET scan, clinical reports, and Medicare Part A, B, and D claims data. Our study will inform the urgent call from The Institute of Medicine to establish comprehensive policies to support family caregivers in the US by providing findings on the value of information from diagnostic scans, as well as the impact of a scan on care-seeking behavior, planning, emotional well-being, and economic security. The proposed CARE IDEAS study will fill important gaps in our understanding of how care partners and patients react to the results of amyloid PET scans. Merging CARE IDEAS survey data with IDEAS data, we will: (Aim 1) enhance our understanding of the reasons for pursuing a definitive diagnosis of the “cause” of cognitive deficits and the importance of learning the amyloid PET scan results, and characterize concordance within dyads about test importance; (Aim 2) estimate whether patients with a diagnosis of cognitive impairment due to AD, based on the amyloid PET scan, pursue fewer Medicare- reimbursed AD-related diagnostic tests compared to patients with negative scans; (Aim 2.1) empirically estimate whether concordance between patients' and care partners' perspectives about the importance of obtaining definitive diagnostic results leads to fewer AD-related diagnostic tests; (Aim 3) estimate whether patients with positive scans are more likely to adopt advanced directives, compared to patients with negative scans; (Aim 3.1) explore the effect of patient and care partner knowledge about preferences for care and concordance in preferences for care on the adoption of advanced directives; (Aim 4) estimate whether care partners of patients with positive sc...