The importance of lowering blood pressure in hypertensive subjects is well known and studies suggest that lowering of blood pressure in patients who may already be in the normotensive range further reduces the risk of vascular events, particularly stroke. Epidemiological data have also shown that lower blood pressure and antihypertensive treatment may be associated with cognitive impairment once cerebrovascular disease is established. However, the relationship between hypertension and cerebrovascular disease is more complex than suggested by epidemiological or intervention studies and this book investigates the relationship between blood pressure, white matter disease load and cognitive performance in patients with cerebral small vessel disease.