ALZHEIMER-LIKE VISUAL DEFICITS IN DOWN-SYNDROME

Patients with Alzheimer disease (AD) show visual impairments in color discrimination (blue hues), stereoacuity, and contrast sensitivity. We asked whether the AD-type visual profile occurs in Down syndrome (DS) in light of the fact that AD neuropathology is present in DS by age 4 0. We tested 22 adults with DS and 18 adults with mental retardation o f non-DS etiology (MR). DS subjects made more tritanomalous errors on the test of color vision than predicted by chance (p < 0.05), indicati ng a deficiency in the discrimination of short wavelengths (blue hues) but not more of other types of hue discrimination errors. DS subjects had higher stereoacuity thresholds than MR subjects (p < 0.01) and re duced contrast sensitivity across the frequency range (p < 0.01). Take n together, the results point to AD-like visual deficits in DS. Like c lassic AD, DS may be associated with pathological changes in the paras triate and peristriate visual cortex. DS performance was not correlate d with age, suggesting that in individual subjects, the AD-like visual deficits may present prior to and independent of age-associated demen tia.