Hypertension is a particularly important risk factor for hemorrhagic stroke, though it contributes to atherosclerotic disease that can lead to ischemic stroke as well. 9 Risk factors for hemorrhagic and ischemic stroke are similar, but there are some notable differences there are also differences in risk factors among the etiologic categories of ischemic stroke. Ischemic stroke can be further divided into what have been referred to as etiologic subtypes, or categories thought to represent the causes of the stroke: cardioembolic, atherosclerotic, lacunar, other specific causes (dissections, vasculitis, specific genetic disorders, others), and strokes of unknown cause. Hemorrhagic strokes can be either primarily intraparenchymal or subarachnoid. The majority (approximately 80%) of strokes are ischemic, although the relative burden of hemorrhagic versus ischemic stroke varies among different populations. At the most basic level, stroke is divided into hemorrhagic and ischemic strokes. Unlike myocardial infarction, which is almost always due to large vessel atherosclerotic disease affecting the coronary arteries, identification of risk factors for stroke is complicated by the fact that strokes come in many varieties. Furthermore, the global burden of stroke is high, with stroke remaining the fourth leading cause of death worldwide, with a particularly large impact in developing nations. It is increasingly appreciated, for example, that subclinical cerebrovascular disease-including so-called “silent infarction” identified on brain imaging in up to 28% of the population over age 65 6, and ischemic white matter disease-is associated with memory loss, dementia, gait impairment, and other functional disability. 3, 5 It is likely that estimates of morbidity and cost burden, moreover, based on studies of clinical stroke and using traditional measures such as physical disability and healthcare costs, underestimate the burden of cerebrovascular disease. The morbidity associated with stroke remains high, with costs estimated at $34 billion per year for healthcare services, medications and missed days of work. Reasons for this remain uncertain, but could reflect the consequences of the obesity epidemic, and associated diabetes. 3, 4 While stroke mortality had decreased in the US over the past two decades, recent trends in mortality indicate that these decreases may have leveled off, and that stroke mortality may even be rising again. 1, 2 The aging of the population, coupled with the reduction in case fatality after stroke, is expected to increase the prevalence of stroke by 3.4 million people between 20. Stroke is the leading cause of long-term adult disability and the fifth leading cause of death in the US, with approximately 795,000 stroke events in the US each year.