The GERAS Study-US was a prospective, multi-center, observational study that aimed to assess societal costs and resource use associated with Alzheimer's Disease (AD) among patients and their primary caregivers in the United States. Eligible patients were recruited across 76 sites in the United States, were between the ages of 55 and 85 years at baseline, met criteria for early AD in the opinion of the enrolling physician and had partners who were willing to participate. They were followed up for three years.