Vanderbilt Memory and Aging Project

Inclusion Criteria: * Participants recruited will include 1,000 adults age 50 and older. * After the eligibility visit, a small portion of participants (\~150) enrolling must meet diagnostic criteria for mild cognitive impairment according to a clinician diagnosis and/or medical records (i.e., participants must have mild memory or cognitive problems, but they must be free of any functional problems and not have Alzheimer's disease or another form of dementia). The remaining \~850 participants will be cognitively unimpaired adults age 50 and older. * Because the neuropsychological tests used to measure cognitive performance are validated on English-speaking populations, we require that English be the primary language of all participants. Exclusion Criteria: * No available reliable study partner * History of major psychiatric illness (e.g., schizophrenia, bipolar), neurological illness (e.g., stroke, epilepsy, multiple sclerosis, Parkinson's disease, dementia), or head injury with significant loss of consciousness. These exclusion criteria have been applied because they affect brain structure and function. * Diagnosis of congestive heart failure * Diagnosis of atrial fibrillation or other heart arrhythmia * Diagnosis of Chronic obstructive pulmonary disease * Diagnosis of cancer (current) * History of serious alcohol or drug abuse (past or current) * Participants unable to undergo MRI will be excluded. Reasons may include: a. Subjects who have any type of bioimplant activated by mechanical, electronic, or magnetic means (e.g., cochlear implants, pacemakers, neurostimulators, biostimulators, electronic infusion pumps, etc.). b. Subjects who have any type of ferromagnetic bioimplant that could potentially be displaced. c. Subjects who have cerebral aneurysm clips. d. Subjects who may have shrapnel imbedded in their bodies (e.g., from war wounds), metal workers and machinists (e.g., potential for metallic fragments in or near the eyes). e. Subjects who are pregnant. Given that the minimum age of recruitment for the current study is 50 years of age, it is unlikely that prospective participants will be excluded because of pregnancy. f. Subjects who have excessive amounts of metal dental work based on records released by their dentist.