GREATER RELATIVE IMPAIRMENT OF OBJECT RECOGNITION THAN OF VISUOSPATIAL ABILITIES IN ALZHEIMERS-DISEASE

Histological investigation in Alzheimer's disease (AD) has indicated t hat the concentration of neurofibrillary tangles in inferotemporal cor tex (IT) is greater than that found in posterior parietal cortex (PPC) . Researchers hypothesized that the relative degree of impairment of v isual function subserved by each of these cortical areas should reflec t the disproportionate distribution of neuropathological changes. Elev en AD patients and 16 elderly controls received 8 tests of visual func tion, 4 of which have been shown previously to be selectively affected by IT lesions and 4 that are selective for PPC lesions. AD patients w ere significantly impaired on all 8 tests, but multivariate analysis i ndicated a relatively greater impairment on tests of IT function. The greater impairment of visual function mediated by IT relative to funct ion mediated by PPC is consistent with differential degradation of the respective cortical areas.