VISUAL PERCEPTION AND ALZHEIMER'S DISEASE

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Alzheimer's disease is an insidious affliction that cripples the cognitive capabilities of its victims. While memory complaints are the hallmark of the illness, perceptual disorders also are prevalent. Recent research has demonstrated that there are profound deficits in early visual information processing associated with Alzheimer's disease. The evidence suggests that the visual experience of the Alzheimer patient is very different from that of healthy, elderly adults. It is the premise of this proposal that the altered perceptual experiences can have a severe impact on a wide range of perceptual-cognitive functions. The major objective of the research project is to examine the hypothesis that individuals suffering from Alzheimer's disease experience a marked loss in visual perception functions at an early stage of the disease. The objective will be explored through three specific aims using the tools of visual psychophysics and image analysis technology. The first aim is to collect longitudinal, normative data on contrast sensitivity for low and high spatial frequencies from individuals diagnosed with probable Alzheimer's disease, and healthy, elderly adults. It is expected that this measure of visual function will demonstrate a marked loss in Alzheimer's victims that may serve as an early marker of the disease. The second aim is to directly relate the loss of spatial frequency sensitivity to the functional perceptual problems experienced by the patients in basic visual processes such as letter identification, and pattern recognition. Finally, the efficacy of vision and/or stimulus enhancement as an intervention technique for reducing the severity of the perceptual impairment will be explored with the aid of an image engineering workstation that will be developed in the project. The wealth of information made available through this project will assist the clinician in diagnosing dementia. Furthermore, when taken in conjunction with the studies on information processing skills, these data will assist the clinician in describing the true functional capabilities of the patient in the visual processing domain.