Clinical Utility of Early vs. Late Blood Biomarker Testing for Alzheimer's Disease

Inclusion Criteria: 1. Minimum age: 50 years. 2. Patients presenting with symptoms of mild cognitive impairment (MCI) or other cognitive impairments in which the enrolling clinician clinically suspects Alzheimer's pathology as the primary cause of symptomatic presentation 3. Patients presenting with mixed brain pathologies including MCI/ cognitive impairments in which the investigator clinically suspects Alzheimer's pathology as the primary or contributing cause of symptomatic presentation 4. Patients are able to attend study visits and standard care visits over the period of 1 year from the date of enrollment 5. Patients are able to undergo routine phlebotomy and provide up to six (6) 10 ml tube(s) of blood for study related tests plus any additional blood necessary for standard laboratory testing at each study timepoint 6. Patients are able to undergo standard care diagnostic procedures to include MRI (or CT), amyloid PET and/or CSF biomarker testing for AD diagnosis if prescribed by investigator 7. Patients are able to provide informed consent. Or, if in the opinion of the clinician, the patient is unable to adequately understand the nature of the trial and protocol requirements, a family member or appropriate representative of the patient is present to consent, with additional assent by the patient. Exclusion Criteria 1. Patients younger than 50 years of age 2. Patients being evaluated for cognitive impairment known to be predominantly the result of a disease or condition other than AD 3. Patients previously diagnosed with AD, unless the ADELAIDE investigator has a strong clinical suspicion suggestive of an incorrect initial diagnosis upon referral 4. Patients with no cognitive impairment or clinical symptoms of AD 5. Patients desiring genetic testing for Alzheimer's disease markers without current cognitive impairment or other relevant clinical symptoms 6. Patients who are not able or not willing to undergo standard care diagnostic procedures to include MRI (or CT), amyloid PET and/or CSF biomarker testing for AD diagnosis as prescribed by investigator 7. Patients who are not able to understand the nature of the study nor the study requirements and not represented by a family member or other appropriate representative who is able to consent on behalf of the patient 8. Patients who are not able to commit to attending the required study and/or standard care visits 9. Patients who are not able to undergo routine phlebotomy or provide blood samples in the quantity required by the study protocol