Abstract
Simultanagnosia, an impairment in simultaneous object perception, has been attributed to deficits in visual attention and, specifically, to processing speed. Increasing visual attention deficits manifest over the course of Alzheimer's disease (AD), where the first changes are present already in its symptomatic predementia phase: amnestic mild cognitive impairment (aMCI). In this study, we examined whether patients with aMCI due to AD show simultaneous object perception deficits and whether and how these deficits relate to visual attention. Sixteen AD patients with aMCI and 16 age-, gender-, and education-matched healthy controls were assessed with a simultaneous perception task, with shapes presented in an adjacent, embedded, or overlapping manner, under free viewing without temporal constraints. We used a parametric assessment of visual attention based on the Theory of Visual Attention. Results show that patients make significantly more errors than controls when identifying overlapping shapes, which correlate with reduced processing speed. Our findings suggest simultaneous object perception deficits in very early AD, and a visual processing speed reduction underlying these deficits.
Highlights
Deficient memory is considered the hallmark of Alzheimer’s disease (AD), already manifesting in mild dementia and amnestic mild cognitive impairment as a symptomatic predementia phase of AD (Albert, et al, 2011,Morris, et al, 2001,Petersen, 2004)
We examined whether patients with amnestic mild cognitive impairment (aMCI) due to AD show simultaneous object perception deficits and whether and how these deficits relate to visual attention
To assess visual attention, TVAbased whole- and partial-report were applied in all participants, but we only focus on the whole-report results here
Summary
Deficient memory is considered the hallmark of Alzheimer’s disease (AD), already manifesting in mild dementia and amnestic mild cognitive impairment (aMCI) as a symptomatic predementia phase of AD (Albert, et al, 2011,Morris, et al, 2001,Petersen, 2004). Growing evidence suggests the presence of visual attentional impairments early in the course of AD (Alescio-Lautier, et al, 2007,Bonney, et al, 2006,Bublak, et al, 2011,Finke, et al, 2013,Perry and Hodges, 1999,Perry, et al, 2000,Rapp and Reischies, 2005,Redel, et al, 2012,Rizzo, et al, 2000) Significant relationships of such impairments to hypometabolism and functional connectivity changes in frontoparietal attention systems have been documented (Neufang, et al, 2011,Neufang, et al, 2014,Sorg, et al, 2012,Sorg, et al, 2007). In the present study, we asked whether patients with aMCI show deficits in simultaneous object perception and, if so, whether these deficits are associated with a reduction of processing speed
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