Most aspects of visual cognition and memory are impaired in Alzheimer's Disease (AD), including the abilities to recognize and discriminate objects, faces, letters and words, and other patterns. Recent research indicates that deficits in basic vision are prevalent in this disorder and that visual deficits can strongly predict impairments in visual cognition, suggesting that basic vision may be a logical non-pharmacological point of intervention for improving cognition in AD.
The specific aims of the study include experimentally manipulating vision test variables and determining which manipulations most improve performance on tests of targeted cognitive capacities, which begins to address the long-term goal of enhancing cognitive performance in AD through the development of interventions aimed at restoring deficient visual capacities. A dual-site longitudinal study is proposed, using the strengths of the Alzheimer Centers of Boston and Cleveland to effect participant enrollment and data quality. The plan calls for testing 80 healthy elderly adults, 80 healthy young adults, and 160 demented patients, of whom 50% will be diagnosed with probable AD and 35 percent with Vascular Dementia. The remainder will include Lewy Body and Frontotemporal Dementias. Target contrast sensitivity and backward masking, visual capacities that show the most promise as launching points for cognitive intervention, are targeted in this research. A third capacity, motion perception, will be the subject of more preliminary investigation as a possible point of intervention. It is hypothesized that manipulations of stimulus contrast, luminance, and duration will result in significant improvement or even normalization of performance of demented patients on several tests of visual cognition, including letter and word reading, face discrimination and recognition, object naming, and complex pattern completion. For motion perception, the role of the direction of attention and prior adaptation to several types of motion signals will be studied. This research promises to yield data relevant to determining the dynamic cognitive capacities that might be amenable to improvement through manipulation of these motion perception variables. By bridging the findings of visual, cognitive, and clinical deficits to innovative and effective intervention, the project may provide new insights to improving cognition and hence the quality of life of normal elderly adults and especially individuals with AD and dementia of other etiologies.
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