Exploratory analysis of disease progression and natural history of MCI and AD Lead Investigator: Tiimothy Swan Institution : Biogen E-Mail : timothy.swan@biogen.com Proposal ID : 1207 Proposal Description: This dataset is being requested to support Biogen's Alzheimer's Disease program research. There are several key aims of the research, with the expected values described below. (1) Estimates of disease progression (from MCI due to AD to mild, moderate, and severe AD dementia): Improved understanding of expected (i.e., background) progression rates, to allow for more precise and generalisable economic modeling of the impact of future therapy outside of the clinical trial setting. (2) Factors associated with disease progression, including demographic, medical, clinical measures, and biomarkers: Improved prediction of disease progression may help identify patient subgroups with a faster or more burdensome disease course, to support the value of and access to new AD therapies. (3) Prevalence and incidence of comorbidities and use of prescription medications associated with cognitive impairment or medical events, among patients with MCI due to AD or mild AD dementia: Improved pharmacovigilance plan at time of marketing authorization submission regarding the expected (i.e., background) rates of adverse events Improved understanding of the medical characteristics of MCI due to AD and mild AD dementia patients outside of the clinical trial setting that may impact the benefit-risk profile of new AD therapies (4) Characteristics of patients with MCI due to AD and mild AD across different research cohorts: Compare an age-matched population from NACC to other cohort studies in other geographies (e.g., Australian Imaging Biomarkers and Lifestyle Study of Ageing US Mayo Clinic Study of Aging) regarding sociodemographics, biomarkers, APO4 status, cognitive and functional measures.