This study, a parallel ancillary study of the Alzheimer's Disease Neuroimaging Initiative (ADNI), will first examine reproducibility of fMRI activation, using a face-name associative memory paradigm, and then the alterations in memory-related activation that occur over the course of MCI and mild AD. The study will also examine the relationship of fMRI activation to clinical variables, memory task performance, genotype, and other imaging techniques cross-sectionally and longitudinally, sampling at multiple time points over a 3-year period.