| pubmed-article:9194392 | pubmed:abstractText | Constructional apraxia is one of the neuropsychological findings frequently observed in the early stage of the Alzheimer's disease, which may result from the visuo-spatial disturbances. The visual space consists of a variety of visual information processing, viewer-centered coordinate system, objects-centered coordinate system, integration of both coordinate systems, and verifying visual representation with the knowledge in the memory. The reversible operation in space, or mental rotation appears to play an important role in visuo-spatial functions, which refers to the operation of the visual representation at one orientation in viewer-centered coordinate system to construct the representation in object-centered coordinate system so that one can look like if it were presented at another orientation. To the present, little is known about reversible operation or mental rotation in patients with Alzheimer's disease. In this present paper, we attempted to investigate the ability of reversible operations in space so as to understand the mechanisms underlying constructional apraxia, or visuo-spatial disturbances in the early stage of Alzheimer's disease. The subjects were 12 patients with Alzheimer's disease in early stage (AD group), 12 patients with multi-infarcts dementia as disease control (MID group), 12 age matched persons as healthy control (HC group). In perspective taking tasks, that requires the subjects to imagine the spatial arrangement of the objects at the different view points from the subjects' one, AD group showed more severe deficits than MID group and HC group. Moreover, in a task that the subjects were asked to assume the photo-angle of the photograph taken of the model which was in front of them, AD group was imparied compared to the control groups. These disturbances were closely associated with deficits in Block Design test of WAIS. These results clearly demonstrate that the patients with Alzheimer's disease have disturbance in reversible operation in space and that the disturbance may be responsible for visuo-spatial dysfunctions, not only the constructional apraxia, but also a variety of performance deficits in the early stage of Alzheimer's disease. | lld:pubmed |
