Disturbances of spatial vision and object vision correlate differently with regional cerebral glucose metabolism in Alzheimer's disease

There is evidence of two neuronal systems for visual cognition which are re ferred to as spatial vision and object vision. We subjected 49 patients wit h mild-to-moderate probable Alzheimer's disease (AD) to tasks associated wi th these two types of visual cognition. Visual counting was employed as a t ask to assess visuospatial recognition. Identification of overlapping figur es and discrimination of visual forms were used as visuoperceptual tasks th at require an ability to recognize objects. Regional cerebral glucose metab olism (rCMRglc) of the subjects was also deter-mined by positron emission t omography. Multivariate statistics controlling for the confounding factors assessed the correlation between the task performances and the rCMRglc. The visual counting score significantly correlated with the metabolic rate of the bilateral inferior parietal lobules. On the other hand, the scores of t he visuoperceptual tasks significantly correlated with the metabolic rate o f the right middle temporal gyrus and the right inferior parietal lobule. T he present study showed that visuospatial disturbance was related to bilate ral parietal metabolism, and that visuoperceptual disturbance was related t o right temporo-parietal metabolism in patients with mild-to-moderate AD. ( C) 2000 Elsevier Science Ltd. All rights reserved.