The proposed study will be the first to examine whether changes in blood flow patterns within the brain account for the possible cognitive benefits of CR. A clearer understanding of this possibility may provide key insight into the way CVD affects the brain, help identify effective treatments, help a greater number of patients return to work, and improve quality of life.

Based on recent patient referrals, we expect that 30 participants will subsequently enroll in CR and 30 will not. CR patients will complete standardized neuropsychological tests (45-60 minutes) and Transcranial Doppler (30-40 minutes) during their first and last week in the CR program. Patients who do not enroll in CR will undergo testing at similar intervals to serve as a matched control group. Standard medical records will be collected for participants in both groups to obtain demographic and medical information. CR-specific medical records will also be collected to obtain information about possible mechanisms for cognitive benefits (e.g. improved stress test performance, reduced blood pressure, etc.). All participants will be compensated for their time.

Inclusion Criteria:

- 50 to 85 years of age, able to communicate in English, history of heart disease

Exclusion Criteria:

- history of significant neurological disorders, such as stroke, Alzheimer's disease, or severe head injury significant psychological problems such as schizophrenia or bipolar disorder

Those with cardiovascular disease