Comprehensive Care for Alzheimer's Act This bill allows the Center for Medicare and Medicaid Innovation (CMMI) to test a Dementia Care Management Model that provides comprehensive care to Medicare beneficiaries with Alzheimer's disease or a related dementia. Under the model, participating health care providers receive payment under Medicare for comprehensive care management services that are provided to individuals with diagnosed dementia, excluding Medicare Advantage enrollees, hospice care recipients, and nursing home residents. Required services include medication management, care coordination, and health, financial, and environmental monitoring, as well as trainings and other support services for unpaid caregivers. Providers must furnish services through interdisciplinary teams and must ensure access to a team member or primary care provider 24-7. The CMMI must set payments and determine quality measures for the model in accordance with specified requirements. The bill also allows the CMMI to design a similar model under Medicaid.