The last two decades have witnessed increasing research efforts into age-related white matter changes (WMC) and their possible association with clinical deficits. In addition to cross-sectional investigations on representative numbers of individuals, more and more information has come from longitudinal studies. Furthermore, novel analysis and imaging techniques have enabled one to obtain an evermore sensitive and specific view of the range of WMC and the correlation with other morphologic abnormalities. Consistent with prevailing subcortical damage, deficits were seen primarily in the speed of motor and cognitive processing and regarding executive function. In these investigations, an impact on cognitive performance was better demonstrable in non-demented individuals, although extensive WMC were also judged to make a (small) contribution to the cognitive impairment in Alzheimer's disease. Some types of small-vessel disease (SVD)-related morphologic changes, such as lacunar infarcts especially, are certainly also of importance for the development of cognitive dysfunction.