WHITE-MATTER MAGNETIC-RESONANCE HYPERINTENSITIES IN DEMENTIA OF THE ALZHEIMER-TYPE - MORPHOLOGICAL AND REGIONAL CEREBRAL BLOOD-FLOW CORRELATES

In a prospective MRI study the presence, appearance, volume, and regio nal cerebral blood flow (rCBF) correlates of periventricular hyperinte nsities (PVHs) and deep white matter hyperintensities (DWMHs) were exa mined in 18 patients with probable Alzheimer's disease and in 10 age m atched healthy control subjects, all without major cerebrovascular ris k factors. The Xe-133 inhalation method and the [Tc-99m]-d,l-hexamethy l-propyleneamine-oxime (HMPAO) technique with single photon emission c omputed tomography (SPECT) were used to measure rCBF. Rating scores fo r PVHs were significantly higher in the Alzheimer's disease group (p< 0.01) and correlated significantly with the volume of ventricles (p < 0.05) and with systolic arterial blood pressure (p < 0.01), but not wi th rCBF. By contrast, there was no significant difference in the ratin g scores or volumes of DWMHs between the two groups, although three pa tients had extensive DWMH lesions in the central white matter. In the group of patients with Alzheimer's disease as a whole, the volume of D WRMHs correlated well with rCBF in the hippocampal region (r = -0.72; p < 0.001), but not with frontal, temporal, parietal, or occipital rCB F. Postmortem histopathology of extensive DWMH lesions in one patient with definite Alzheimer's disease showed a partial loss of myelin and astrocytic gliosis, but no ischaemic changes. It is concluded that DWM H lesions may be associated with reduced rCBF in the hippocampal regio n. The heterogenous topography of neocortical rCBF deficits in Alzheim er's disease could not be explained by deaf-ferentation from underlyin g white matter hyperintensities and therefore may reflect variations i n the topography of cortical abnormalities.