The carotid arteries are blood vessels in the neck that supply blood to the brain. Carotid stenosis disease is defined as a narrowing of these arteries due to the build up of plaque. The plaque material can also break off and move into the brain. The resulting blockage of blood supply to a portion of the brain is what causes 80% of all strokes. One treatment option is to have surgery on the carotid artery and remove the plaque. This procedure is called a carotid endarterectomy (CEA). There is evidence that proves CEA reduces the risk of stroke. The objective of this research project is to determine who is most likely to benefit from CEA surgery.

Inclusion Criteria:

• Greater than 30 years of age
• Greater than grade 9 education level
• Mini-mental state exam (MMSE) greater than 19 for carotid stenosis patients

Exclusion Criteria:

• History of acute stroke
• History of current psychiatric disorder, such as depression or movement disorder
• Diagnosed Alzheimer's Disease or dementia

Atherosclerosis is a major risk factor for ischemic cerebrovascular events such as stroke (Bots, Hoes et al. 1997). Carotid endarterectomy (CEA) and carotid stenting (CAS) are common surgical procedures aimed at reducing stroke risk. For individuals with symptomatic stenosis > 70%, CEA has a higher event-free survival compared to medical therapy (Barnett, Taylor et al. 1998) and is considered highly beneficial treatment (Rothwell, Eliasziw et al. 2003). To date, however, few studies have attempted to relate effects of the surgery to changes in brain physiology and function.