Inclusion Criteria:

• Aged 40-65 at study entry.
• For persons enrolling in GRoW, age 40-89.
• Have at least one biological parent diagnosed with dementia due to AD; OR, neither biological parent with a diagnosis of AD (mother lived to 75 years and father lived to 70 years without AD) OR approved by the PI to enroll with indeterminate family history status.
• For GRoW participants, must be a first or second degree relative of the person with AD who was diagnosed by age 75.
• Ability to speak English fluently and ability to understand and be willing to undergo study procedures for the entire length of the study.
• Visual and auditory acuity adequate for neuropsychological testing.
• Good general health with no diseases expected to interfere with the study.
• A spouse, friend or family member that knows the participant well, that can answer informant-based questionnaires and interviews. 

Exclusion Criteria:

• History or diagnosis of a significant learning disability that may interfere with cognitive assessment or obfuscate a cognitive trajectory.
• Major neurological disorders: A prior diagnosis of dementia or MCI; a diagnosis in adulthood of other major neurological disease such as other neurodegenerative disorder; multiple sclerosis, meningitis with focal sequelae or lingering cognitive deficits, clinically significant cerebrovascular accident, significant traumatic brain injury with loss of consciousness of 60 min or more; brain infection, neoplasm, or neurosurgery. 
• Persons with certain cancers in or near the brain whose treatment involved radiation to or near the brain, or chemotherapy within the past 5 years are excluded at entry. These treatments may impact accurate measure of cognitive changes due to aging and or intrinsic AD. 
• Current major Axis I DSM-V disorder that may impact accurate measurement of cognition or obfuscate the effect of aging or AD on cognitive change over time. Examples include bipolar disorder, schizophrenia or other psychotic disorder, severe major depression, self-reported drug or alcohol abuse or dependence that, in the opinion of the study PI or a study clinician may interfere with accurate measurement of cognitive change due to aging or AD.
• Lacks capacity to provide informed consent.
• Active participation in another longitudinal study involving cognition that may interfere with valid cognitive measurement in this study.
• Exceptions may be made by the PI on a case by case basis.