Inclusion Criteria:

1. Males and females (of non-childbearing potential), 50 to 79 years of age.
2. Undergoing CABG surgery with the use of extracorporeal circulation.
3. Willing and able to complete cognitive testing.
4. Score < 16 on the Center for Epidemiological Studies in Depression scale (CES-D).
5. Score > or = 28 on the Mini-Mental State Examination (MMSE).
6. Willing and able to provide informed consent to participate in this study
7. Fluency in written and spoken English.

Exclusion Criteria:

1. Presence of any severe mental illness that could affect interpretation of efficacy data, such as schizophrenia or bipolar affective disorder; any untreated or unstable psychiatric condition including depressive disorder or anxiety disorder.
2. History of stroke or other significant neurological disorder
3. Transient ischemic attack (TIA) with ongoing cognitive sequelae
4. Chronic atrial fibrillation or uncontrolled atrial fibrillation prior to surgery
5. Myocardial infarction (MI) within the last 8 weeks and/or previous history of more than 3 MIs
6. History of liver dysfunction with ongoing sequelae (including but not limited to liver enzymes > 2.5 x upper limit or normal (ULN) at screening).
7. History of renal dysfunction with ongoing sequelae (including but not limited to creatinine value > 2.5 mg/dL at screening).
8. Known active alcohol or drug abuse.
9. Concurrent use of prescription medications known to enhance memory
10. General anesthesia (defined as anesthesia requiring intubation or ventilatory support) within 3 months prior to randomization.
11. Cardiopulmonary bypass or thoracotomy within 2 years prior to randomization.
12. Undergoing valvular repair or replacement during scheduled CABG surgery.
13. Chronic obstructive pulmonary disease (COPD) requiring oxygen therapy.
14. Decompensating congestive heart disease
15. Subjects on immunosuppressive drugs, such as azathioprine, chemotherapeutic agents, mycophenolate, monoclonal antibodies, or more than 20 mg/day prednisone, within the previous 3 months
16. Receipt of any investigational agent or device within 30 days of screening.