Greater relative impairment of object recognition than of visuospatial abilities in Alzheimer's disease.

Abstract

Histological investigation in Alzheimer's disease (AD) has indicated that the concentration of neurofibrillary tangles in inferotemporal cortex (IT) is greater than that found in posterior parietal cortex (PPC). Researchers hypothesized that the relative degree of impairment of visual function subserved by each of these cortical areas should reflect the disproportionate distribution of neuropathological changes. Eleven AD patients and 16 elderly controls received 8 tests of visual function, 4 of which have been shown previously to be selectively affected by IT lesions and 4 that are selective for PPC lesions. AD patients were significantly impaired on all 8 tests, but multivariate analysis indicated a relatively greater impairment on tests of IT function. The greater impairment of visual function mediated by IT relative to function mediated by PPC is consistent with differential degradation of the respective cortical areas.