The purpose of the study is to examine if blood flow in the brain before coronary artery bypass graft surgery has an effect on depression after surgery.

The main hypothesis of the study states that pre-surgical blood flow in the brain will be an independent risk factor for depression after surgery after adjusting for other risk factors such as gender, pre-CABG depression, social support, medical comorbidity burden, socioeconomic status, and neuroticism.

Inclusion Criteria:

• Age: 40 years or older
• Will be having CABG surgery at the Yale New Haven Hospital
• Be able to provide informed consent
• Have a household telephone
• A fluent English speaker, and possessing no communication barrier
• Be able to come to the study site or to have the study team come to his/her home.
• Has a family member or partner/ friend who could provide collateral information

Exclusion Criteria:

• Has had previous CABG surgery
• History of dementia diagnosis or cognitive impairment (CDR >/= 1)
• Auditory or visual impairment that would interfere with study procedures
• Active alcohol or substance abuse problem based CAGE-AID (endorsing two or more items)
• History of Bipolar Disorder, Schizophrenia, Schizoaffective Disorder, or any Psychotic Disorder by medical history or self-report.
• Presence of non-cardiovascular conditions likely to be fatal within 1 year

The study population for this study will be drawn from cardiac surgery patients at a university-based hospital who will undergo coronary artery bypass graft (CABG) surgery.