ADRC Clinical Cohort (Alzheimer's Disease)

Inclusion Criteria: * Each subject must be ≥ 25 to ≤ 80 years of age. * Each subject must be able to read at a 6th grade level, as determined by the investigator, and must have a history of academic achievement and/or employment sufficient to exclude intellectual disability. * Each subject (or legal representative) must sign the informed consent form after the scope and nature of the investigation have been explained to them, and before screening assessments. Some consent may be obtained via phone script and REDCap eConsent. * Each participant must be willing to have an MRI and a lumbar puncture, or alternately (to the lumbar puncture) a series of PET scans. * Each participant ages 45 to 80 must have a study partner who agrees to participate in the study and who is able to read at a 6th grade level, as determined by the investigator, and must have a history of academic achievement and/or employment sufficient to exclude intellectual disability. Exclusion Criteria: * Evidence of a clinically relevant or unstable neurological disorder including history of multiple head injuries, stroke or other CNS conditions (MS, Parkinson's disease, etc.) * Evidence of a clinically relevant or unstable psychiatric disorder. * History of alcoholism or drug dependency/abuse within the last 2 years before enrollment. * GAD-7 score \>9 and/or PHQ-8 score \>9 * An ongoing uncontrolled, clinically significant medical condition such that, in the judgment of the investigator, a subject's participation in the trial would pose a significant medical risk to the subject. * Contraindication or intolerance to 3T MRI investigations, including implanted devices * History of malignancy of any organ system, treated or untreated, within the past 60 months, regardless of whether there is evidence of local recurrence or metastases. However localized nonmalignant tumors not requiring systemic chemo- or radiotherapy, localized basal or squamous cell carcinoma of the skin, or in-situ cervical cancer are permitted.