This research study aims to examine biomarkers of Alzheimer's disease as early as possible which could potentially be a screening tool for the general population. This observational study will take place at the Memory and Aging Program at Butler Hospital. The study will enroll up to 200 cognitively healthy subjects aged 50 to 80 years with ongoing recruitment and enrollment for 2 years, and subject participation lasting approximately 4 years. Disclosure of AD risk assessments will be an optional procedure. Two PET imaging sub-studies will also be optional.

Inclusion Criteria:

• Individuals between the ages of 50 and 80 years old (inclusive)
• Score of 16 or above on the MoCA telephone
• Score of 27 or greater on the MMSE for individuals aged 50 to 64 years old or a score of 26 or greater for individuals aged 65 to 80 years old
• Participants in the 50-60 age range will additionally need to meet at least one of the following: (1) First degree family history of dementia with onset before age 75; (2) APOE e4 allele carrier; or (3) Prior elevated result on amyloid PET or amyloid CSF testing
• Conversationally fluent in English to the extent that an interpreter is not necessary for comprehension of the study information, procedures, and cognitive tests.
• If participants elect to participate in the optional disclosure procedure, they will be required to have an appropriate study partner who agrees to participate in the study and who is intellectually, visually, and auditory capable, and conversationally fluent in English to the extent that an interpreter is not necessary.
• Adequate visual and auditory acuity to allow neuropsychological testing.
• Participants must be willing and able to provide written informed consent.

Exclusion Criteria:

• Diagnosis of mild cognitive impairment or dementia
• History of significant brain injury or other known neurologic disease or insult, resulting in lasting cognitive sequelae that would confound the assessment and staging of potential neurodegenerative disease (e.g., Huntington's disease, Parkinson's disease, Parkinsonism due to multiple system atrophy (MSA), progressive supranuclear palsy (PSP), Shy Drager Syndrome (SDS) or other neuro-degenerative dementias, encephalitis or other brain infection, epilepsy or stroke with lasting impairment to cognitive function).
• Current serious or unstable systemic illness or organ failure that, in the PI's judgement, would make it difficult to participate in the study (e.g., such as terminal cancer, cardiovascular, hepatic, renal, gastroenterological, respiratory, endocrinologic, neurologic, psychiatric, immunologic, or hematologic disease or other conditions ). History of cancer is acceptable with at least one year in remission with a good prognosis.
• Individuals with clinically significant depression, bipolar disorder, anxiety, or suicidal ideations within the past year as defined by the most current version of the Diagnostic and Statistical Manual of Mental Disorders (DSM).
• A history of schizophrenia as defined by the most current version of the DSM.
• History within the past year of chronic alcohol or drug abuse/dependence as defined by the most current version of the DSM.
• Marijuana use is acceptable, but frequent users will be asked to abstain from use within 24 hours of any assessments.
• Refusing or unable to complete any study procedures.
• Currently enrolled in another study which involves clinical drug trial or other medical intervention.

This study will be conducted in up to 200 subjects between the ages of 50-80 who are cognitively unimpaired. Participants must also pass all inclusion/exclusion criteria.