Postoperative cognitive decline (POCD) affects up to 50% of non-cardiac surgical patients greater than or equal to 65 years of age.

This study will test the hypothesis that preoperative presence of brain beta-amyloid plaques in non-demented subjects increases postoperative cognitive decline (POCD) in elderly subjects scheduled for hip or knee replacement.

The investigators hypothesize that preoperative beta-amyloid plaques will predict postoperative cognitive decline.

Inclusion Criteria:

• Scheduled for total knee arthroplasty or total hip arthroplasty under general anesthesia (primary arthroplasties and revisions)
• English speaking
• Anticipated stay in the hospital
• Not anticipated to stay intubated postoperatively
• Patients who live with or have regular visits from an individual ("study partner") willing to provide information about the patient's cognitive status
• Willing and able to undergo all testing procedures including neuroimaging and agree to longitudinal follow up
• Adequate visual and auditory acuity to allow neuropsychological testing
• Subjects with Clinical Dementia Rating Scale (CDR) of 0-0.5
• Patients who are not demented
• Subjects sho signed an IRB approved informed consent prior to any study procedures

Exclusion Criteria:

• Clinically significant hepatic, renal, pulmonary, metabolic, or endocrine disturbances as indicated by history, which in the opinion of the investigator might pose a potential safety risk to the subject
• Current clinically significant cardiovascular disease.
• History of drug or alcohol abuse within the last year, or prior prolonged history of abuse
• Clinically significant infections disease, including Acquired Immune Deficiency Syndrome (AIDS) or Human Immunodeficiency Virus (HIV) infection or previous positive test for hepatitis
• History of relevant severe drug allergy or hypersensitivity
• Received an investigational medication under an FDA IND protocol within the last 30 days.
• Current clinically significant unstable medical comorbidities, as indicated by history or physical exam, that pose a potential safety risk to the subject
• Received a radiopharmaceutical for imaging or therapy within the past 24 hours prior to the imaging session for this study
• Severe psychiatric disorders including schizophrenia, bipolar disorders, and major depression as described in DSM-IV within the past year (medical record, GDS score, interview with the patient and study partner)
• Obvious causes for their cognitive impairment (e.g. onset coincides with recent head trauma or stroke)
• Dementia of any cause
• CDR score > 0.5
• Expressed the preference to undergo the procedure under regional anesthesia in form of spinal or epidural anesthesia
• Patients who, in the opinion of the investigator, are otherwise unsuitable for a study of this type