VISION IN ALZHEIMERS-DISEASE

Disturbances of visual function can be the first symptom of Alzheimer disease (AD). Several cases of pathologically proven AD associated wit h Balint's syndrome have been reported, and, in most of them, an unusu al occipito-parietal predominance of neurofibrillary tangles (NFT) and neuritic plaques (NP) was found Systematic assessment of visual funct ions in groups of patients presenting with dementia of Alzheimer type (DAT) have shown deficits in several tests, especially in stereo-acuit y, in motion sensitivity, in contrast sensitivity for low spatial freq uencies and in backward masking sensitivity. In electrophysiological s tudies, abnormalities of flash visual evoked potentials, contrasting w ith preservation of pattern visual evoked potentials, have been repeat edly reported Moreover, decreased glucose metabolism in visual associa tion cortex and in partietal cortex is frequent in DAT. Quantitative s tudies of regional distribution of NFT and NP in AD indicate constant involvement of associative visual cortex and preservation of primary v isual cortex. All these findings, taken together, suggest that the occ ipito-parietal cortex which constitutes the dorsal visual system and s ubtends visuo-spatial functions, is selectivly affected in AD.