A study of regional cerebral blood flow and cognitive performance in Alzheimer's disease.

Abstract

Thirty five patients with dementia of the Alzheimer type (DAT) and 35 controls matched for age, sex and handedness were investigated using single photon emission computer tomography (SPECT) with 99m technetium HMPAO. Regional cerebral blood flow (rCBF) was assessed semiquantitatively in 18 cortical and 4 subcortical areas by normalising mean information density in each region to cerebellar mean information density. Analysis revealed significantly reduced rCBF to temporal, parietal, frontal and left occipital cortex in the patients whilst blood flow to subcortical areas showed no differences between the 2 groups. In addition, significant left-sided cortical hypoperfusion was seen in the DAT group but not in controls. When patients were subdivided on the basis of disease severity, those with mild disease showed temporal, parietal and left frontal changes with more severely affected patients also showing right frontal and left occipital involvement. rCBF patterns did not distinguish between presenile and senile onset cases once duration and severity of illness were controlled. Eight cortical areas were also rated visually for perfusion deficits on a simple 4 point scale. Perfusion deficits were detected in 34 of 35 patients but in only 4 of 35 controls. In the DAT group significant correlations were found between many of the neuropsychological tests used and rCBF. Memory correlated with left temporal activity, praxis, perception, object assembly and block design with right parietal activity and language with activity throughout the left hemisphere. Significant correlations were also seen between subcortical and cortical blood flow, possibly explaining the correlations observed between many of the neuropsychological tests and thalamic blood flow.

Cerebral Hypoperfusion Generates Cortical Watershed Microinfarcts in Alzheimer Disease

“…19 -25 Several earlier studies reported reduced cerebral blood flow in AD. [5][6][7][22][23][24][25]28,29 Pavics et al, 30 studying regional cerebral blood flow, showed that bilateral cerebral hypoperfusion occurs in the temporal and/or parietal region in 70% (23/33) of patients with AD and in 33% (6/18) of patients with vascular dementia. Many authors have concluded that diffuse cerebral hypoperfusion is responsible for leukoaraiosis in AD.…”

Are Alzheimer’s disease, hypertension, and cerebrocapillary damage related?☆

“…Clinical measurements of regional CBF by the noninvasive SPECT method have indicated that AD is accompanied by a decreased regional CBF in the hippocampal formation, the temporal cortex, the parietal cortex and the frontal cortex [4,11,13,29,36,40,41,46,53]. The region specificity is remarkable because the typical neuropathological hallmarks of AD also appear first and most extensively in the entorhinal region and the temporal cortex.…”

The neural substrates of memory systems impairment in Alzheimer's disease. A PET study of resting brain glucose utilization

“…This metabolic heterogeneity plays a major role in the neuropsychological profile in Alzheimer's disease, as shown by reproducible correlations between corresponding cognitive and metabolic ratios (Haxby et al, 1988;Penniello et al, 1995; for reviews, see Haxby, 1990;Friedland, 1990). Some studies, using PET (McGeer et al, 1990;Jagust et al, 1993;Ichimiya et al, 1994;Slansky et al, 1995;Soininen et al, 1995;Ishii et al, 1996;Meltzer et al, 1996), or SPECT which provides only semi-quantitative perfusion images with lesser resolution (Goldenberg et al, 1989;Besson et al, 1990;O'Brien et al, 1992) have reported significant correlations between memory scores and cerebral metabolism or blood flow in Alzheimer's disease. However, these studies did not focus on the neuronal systems underlying memory impairment in Alzheimer's disease, i.e.…”