Equivalent spatial-rotation deficits in normal aging and Alzheimer's disease.

Two tests of spatial-rotation ability were administered to 17 young normals, 23 aged normals, and 51 patients with diagnoses of Alzheimer's disease (AD). The AD patients consisted of 28 early dementia patients and 23 advanced dementia patients. On a computerized version of the Boston Naming Test, 40 objects were presented for naming, 20 of which were rotated 180 degrees. The subjects' capacity for mental rotation was assessed on the basis of their accuracy of naming of rotated vs. unrotated objects. On Money's Standardized Road Map Test, in which the subject is asked whether turns on a map are to the left or to the right, spatial-rotation ability was assessed on the basis of the subject's left-right orientation on turns with movement away from the subject (requiring no rotation) vs. turns with movement toward the subject (requiring rotation). Performance on both tasks was progressively worse in the young normal, aged normal, early dementia, and advanced dementia groups. Both tasks demonstrated a clear spatial-rotation deficit in the elderly. Although the spatial-rotation effect was superimposed upon deficits in naming and left-right orientation in the demented subjects, the magnitude of the rotation effect did not significantly differ in the aged normal vs. the early dementia group on either task, suggesting that early AD produces no further impairment of spatial-rotation abilities than is produced by normal aging.