Alzheimer's dementia (AD) is the sixth leading cause of death in the U.S., with an estimated $305 billion cost of care in 2020. Currently there are no cures or therapies to ameliorate the disease progression and symptoms. Growing evidence links a diet characterized by high antioxidant components with benefits to cognitive function, which is indicative of the preventative potential of dietary inteventions. The Mediterranean-DASH Intervention for Neurodegenerative Delay (MIND) study is a 3-year, multicenter, randomized controlled trial to test the effects of the MIND diet on cognitive function in 604 individuals at risk for AD. Men and women ages 65 to 84 years were recruited. Eligible participants were randomized to either the MIND diet with mild caloric restriction or their usual diet with mild caloric restriction. Cognitive assessments, medical history, blood pressure, anthropometric measurements, and blood and urine sample collections will be taken at baseline and follow-up visits. MRI scans will be completed on approximately half of the enrolled participants at the start and end of the study. Unique features of the MIND study include: 1) a dietary pattern, rather than single nutrient or food, tested in an at-risk population; 2) foods featured as key components of the MIND diet (i.e. extra-virgin olive oil, blueberries, and nuts) provided for participants; and 3) MRI scans of brain structure and volume that may provide potential mechanistic evidence on the effects of the diet. Results from the study will be crucial to the development of dietary guidelines for the prevention of AD.