Affiliations: Departments of Neurology, Brain and Cognitive Sciences, Neurobiology and Anatomy, Ophthalmology, and The Center for Visual Science, University of Rochester Medical Center, Rochester, NY, USA
Correspondence:
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Correspondence to: Charles J. Duffy, MD, PhD, Department of Neurology, University of Rochester Medical Center, 601 Elmwood Avenue, Rochester, NY 14642-0673, USA. Tel.: +1 585 273 1696; Fax: +1 585 276-2207; E-mail: Charles_Duffy@urmc.rochester.edu.
Abstract: We tested whether visual processing impairments in aging and Alzheimer's disease (AD) reflect uniform posterior cortical decline, or independent disorders of visual processing for reading and navigation. Young and older normal controls were compared to early AD patients using psychophysical measures of visual word and motion processing. We find elevated perceptual thresholds for letters and word discrimination from young normal controls, to older normal controls, to early AD patients. Across subject groups, visual motion processing showed a similar pattern of increasing thresholds, with the greatest impact on radial pattern motion perception. Combined analyses show that letter, word, and motion processing impairments are independent of each other. Aging and AD may be accompanied by independent impairments of visual processing for reading and navigation. This suggests separate underlying disorders and highlights the need for comprehensive evaluations to detect early deficits.
