Altered signal intensity in the subcortical white matter on magnetic resonance imaging of the brain, referred to as leukoaraiosis, is frequently observed on imaging studies in elderly persons and was previously considered a benign accompaniment of aging. However, recent studies have found a clear association between the presence of leukoaraiosis and an increased risk for stroke, cognitive decline, and dementia. Moreover, epidemiologic studies have shown an association of leukoaraiosis with age, and several risk factors that are amenable to treatment, including smoking, hypertension, diabetes, homocysteinemia, hyperlipidemia, and excess alcohol use. Although results from prospective trials are not available, current evidence suggests that vigorous treatment of cardiovascular disease risk factors may prevent the development or progression of leukoaraiosis and the attendant risks of stroke and dementia.