Background: We studied the costs of formal and informal care in relation to Alzheimer's disease (AD) progression. Methods: 231 persons with AD with a family caregiver were followed up for 5 years. The Clinical Dementia Rating Scale-Sum of Boxes (CDR-SB) was used to measure AD progression. Health and social care unit costs were used for formal care costs. An opportunity cost method for lost leisure time was applied to analyse the cost of informal care.