Objective: To examine the effect of viewpoint and visual texture on visual object recognition in mild cognitive impairment (MCI) or dementia due to DLB or AD.

Background: Visual recognition of objects relies not only on their shape but also on their color or texture. When shape is not perceived sufficiently, e.g. from non-canonical views, color and texture are critical to identify the object. Although various visuoperceptual /visuospatial deficits in Dementia with Lewy Bodies (DLB) and visuospatial deficits in Alzheimer’s disease (AD) have been reported, few studies investigated viewpoint-dependent object recognition and the associated factors in these patients.

Methods: Twenty-five patients with probable DLB, 53 patients with probable AD, and 32 age-matched healthy controls participated in the study. Patients were classified according to the clinical dementia rating (CDR) scale. We administered standard neuropsychological and visuoperceptual assessments, and the visual object recognition task with four types of stimuli; non-canonical view with blurry texture, non-canonical view with clear texture, canonical view with blurry texture, canonical view with clear texture.

Results: Compared to the healthy controls, DLB patients were significantly impaired on the object recognition task with all the four types of stimuli, while AD patients was impaired only with stimuli from non-canonical views. In patients with MCI due to DLB and AD, impairment of object recognition was observed in stimuli from non-canonical views with blurry texture.

Conclusions: Object recognition from non-canonical view without texture cue is significantly obstructed from the early stage of DLB or AD. Combined effects of viewpoint and visual texture on visual object recognition were more evident in DLB than AD, which might be related to the fact that there are visual hallucinations or pareidolia in DLB patients. This work was supported by Grant-in-Aid for Scientific Research on Innovative Areas (No. 17K01480) from MEXT, Japan.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/effect-of-viewpoint-and-visual-texture-on-object-recognition-in-dementia-with-lewy-bodies-and-in-alzheimers-disease/