GOAL and RAPID Studies: Purpose: The purpose of these studies is to identify biological, environmental, social, and behavioral factors that influence risk for or protection against age-related cognitive decline and Alzheimer's Disease and Related Dementias (ADRD). The researchers hope to learn more about the causes of age-related cognitive decline and ADRD, how to prevent, and how to better treat them from the information that you and other participants provide in this study. GOAL Procedures: The main things that will happen in this study are blood draw, tear fluid collection, review of your medical history and records, physical and neurological examination, cognitive testing, completion of questionnaires, brain MRI, and assessments of your walking, strength, smell, and eye structure, function. A study partner, such as a close friend or family member (if available) will also be invited to answer questions about your thinking, mood, and daily functioning. OPTIONAL procedures include a lumbar puncture (LP) and eye dilation. The procedures in this study are conducted in-person. RAPID Procedures: The main things that will happen in this study are a medical record review, completion of surveys, blood collection, and brief cognitive testing. If you are undergoing a lumbar puncture (LP) or blood draw for clinical purposes, we will ask to store or draw additional fluid for research purposes. Tear fluid collection is an optional study procedure. The main study procedures can be completed in person or entirely remotely. Duration of GOAL or RAPID: You will be invited to complete the study procedures each year. There is no prespecified end date for this study. You may remain in the main study as long as you are (1) willing to participate, (2) remain eligible for the study procedures, and (3) the study remains open.