Abstract

Studies on contrast sensitivity function (CSF) in Alzheimer’s disease (AD) have produced conflicting results, with some investigators suggesting that CSF is impaired generally¹ and others reporting that CSF is normal in AD.² An explanation for the discrepancy in results may involve the range of dementia severity represented by the subject groups in the two studies: Many moderately to severely demented subjects with AD are unable to perform particular CSF tests due to memory, attentional, or other deficits unrelated to visual skills. We have administered to a group of ten patients with AD, of a wide range of dementia severity, a CSF test with low task demands. Sinusoidal gratings of six spatial frequencies (1.5, 3, 6, 12, and 18 cycles/deg) and eight levels of contrast were displayed on photographic plates; subjects indicated the orientation of the gratings (vertical, left oblique, or right oblique). Patients who had been unable to perform tests of CSF involving monitor display of static vertical gratings performed ably with the photographic plates. The results indicate that CSF is depressed at each frequency tested for patients with AD relative to healthy age-matched subjects. This deficit appears to be unrelated to the severity of dementia.

© 1987 Optical Society of America