DIFFUSE VACUOLIZATION (SPONGIOSIS) AND ARTERIOLOSCLEROSIS IN THE FRONTAL WHITE-MATTER OCCURS IN VASCULAR DEMENTIA

Objective: To examine quantitatively white-matter changes at different sites in patients with definite vascular dementia and Alzheimer's dis ease. Design: Prospective clinical and neuropathological series. Setti ng: University hospital clinics (Helsinki, Finland, and London, Ontari o).Subjects: Twenty-two patients with a clinical and neuropathological diagnosis of vascular dementia and 20 patients with Alzheimer's disea se. Measures: The frequencies of focal white-matter lesions, arteriolo sclerosis, and cerebral amyloid angiopathy were assessed. Validated ra tings and cell counts were done in the subcortical U-fiber, centrum se miovale, and periventricular areas of the frontal white matter. Degree s of abnormality (none, mild, moderate, severe) were rated for spongio sis (vacuolization of white matter), etat crible (widening of perivasc ular spaces), myelin loss, oligodendrocyte density, axonal loss, and o verall. Densities of oligodendrocytes and astrocytes (cells per square millimeter) were determined. Results: Patients with vascular dementia showed focal white-matter lesions and arteriolosclerosis more often t han patients with Alzheimer's disease. The patients with vascular deme ntia also had significantly greater spongiosis (P<.001), etat crible ( P=.004), myelin loss (P=.005) and overall white-matter abnormality (P< .001). Arteriolosclerosis was found in association with spongiosis but not with etat crible. Cerebral amyloid angiopathy did not appear to b e related to any of the white-matter changes in patients with either v ascular dementia or Alzheimer's disease. The U-fiber area showed fewer changes, and the periventricular area tended to be most affected. Con clusion: In addition to focal infarcts, patients with vascular dementi a showed widespread diffuse changes, including spongiosis and arteriol osclerosis, along with etat crible and myelin loss. White-matter chang es in patients with Alzheimer's disease could not be related to infarc tion. Pathologic changes in small blood vessels are associated with di ffuse white-matter changes and may have a distinct role in the genesis of vascular dementia.