In the paper from the Rotterdam Scan Study (this issue pp9-14),1 de Leeuw et al take another step towards understanding the conundrum of white matter disease (leukoarosis) and its associations with aging and gender. This will hopefully lead towards better understanding of cognitive decline with age, Alzheimer's disease, and vascular dementia.

The assessment of the role of white matter disease in these processes poses several problems. White matter disease is difficult to quantify. The existence of upwards of some 12 different scales for assessing white matter lesion load, few of which have been validated for interobserver or intraobserver variability, or tested in populations other than the one in which they were generated, testifies to the difficulty of trying to make some sense out of different degrees of …