Imaging and neuropsychologic study of Alzheimer's disease and multiple infarct dementia

Iodine-123 single photon emission computed tomography (SPECT) and magnetic resonance imaging (MRI) were undertaken in 8 patients with Alzheimer's disease (AD) and 7 patients with multiple infarct dementia (MID). Imaging features and their relationship to neuropsychologic findings were examined. The group of AD patients had markedly decreased activity in the bilateral parietal-occipital areas on SPECT and relatively marked atrophy in the corresponding area and thinning in the posterior part of callosal stem on MRI. The group of MID patients had a widespread and inhomogeneously decreased activity in the frontal lobe and mottled decrease of activity in the other cortical areas on SPECT. Neuropsychologic symptoms steming from the parietal-occipital area, which is considered as an causative area for AD, were frequently observed in the AD group, as opposed to the lack of these symptoms in the MID group. In both AD and MID groups, there was a good correlation between the areas with decreased activity on SPECT and atrophy on MRI. These imaging appearances were correlated with the occurrence of neuropsychologic symptoms as well. The importance of the parietal-occipital lobe that is likely responsible for the pathogenesis of dementia for AD is emphasized. (Namekawa, K.)