White matter changes in dementia: does radiology matter?

White matter changes are frequently seen on MRI in elderly patients. The significance of these changes is still debated. The origin of white matter changes is heterogeneous but the majority are due to arteriosclerosis in brain vessels. The clinical consequence of the presence of white matter changes in relation to dementia is still unclear. Lately, however, many studies have found a relation between the presence and the degree of white matter changes and cognitive dysfunction. This is most obvious in vascular dementia, but has also been suggested to be of importance in Alzheimer's disease. In this review we discuss the background of these changes and the clinical consequences of them in relation to cognitive disorders.