Comparisons of polio-araiosis and leuko-araiosis in dementias of ischemic vascular and alzheimer types.

Computed tomography scanners were utilized to quantitate, by Hounsfield unit (HU) densities, normal and abnormal cerebral gray and white matter compartments and their perfusion values, among patients with probable dementia of ischemic vascular (IVD: n= 10,72.7 ± 9.0 years) and Alzheimer's types (DAT: n = 10, 72.7 ± 5.8 years). Results were compared with similar measures among age-matched normal volunteers (n = 10, 71.0 ± 8.2 years). "Normal" HU values for gray and white matter were previously obtained among younger normal volunteers (n = 27, 49.7 ± 8.9). After adjusting for cerebral atrophy, IVD patients showed reduced HU and cerebral blood flow (CBF) values in white matter, but gray matter HU values were only reduced in frontotemporal cortex. In DAT, mean HU and CBF values for cortical and subcortical gray matter were severely reduced compared with age-matched normal and with IVD patients. Cognitive test performance correlated directly with volumes of hypodense cortex or "polio-araiosis" in DAT, but not in IVD, in which cognitive performance correlated directly with volumes of leuko-araiosis.