White Matter Hyperintensities and Cognition

Despite the well-established relationship between cerebrovascular disease (CVD) and cognitive decline, confusion remains regarding the clinical importance of the white matter hyperintensities (WMH), also called leukoaraiosis ( 1 ), that frequently appear on neuroimaging. These phenomena, when occurring in patients who have risk factors for vascular disease and stroke, are typically interpreted as evidence of small-vessel ischemic disease ( 2 ), although they can also be the result of other processes. However, the clinical significance of these changes is a matter of debate in both the scientific literature and the daily work of clinicians. This point is illustrated by the fact that although one clinician may consider WMH on magnetic resonance imaging (MRI) as validation of the working diagnosis of vascular dementia (VaD), another may interpret a nearly identical scan as “normal for patient’s age” and move on to consider other causes of cognitive decline. That this situation exists is hardly surprising, because of the contradictory literature on the topic and the variable importance of WMH in the various sets of diagnostic criteria for vascular-related cognitive conditions. This chapter represents an attempt to summarize the existing literature on this topic, as well as present key issues for continued research and debate. These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.