Visual working memory is impaired in Alzheimer's disease: evidence from real-world objects and perceptual organization.

The mechanisms underlying cognitive impairment in Alzheimer's disease (AD) remain poorly understood. Visual working memory (VWM) is a core cognitive function, and its impairment has been linked to the progression has been identified as a reliable predictor of progression from mild cognitive impairment to AD. Both VWM encoding and maintenance can be enhanced by prior knowledge, i.e., top-down modulation, and by perceptual processing, which operates in a bottom-up manner. Using real-world objects and Kanizsa figures, the present study investigated how top-down and bottom-up processes influence VWM performance, thereby providing insight into the cognitive processes underlying AD-related deficits. Results indicated that memory set size and disease status significantly affected performance in both the real-object and Gestalt organization tasks. AD patients did not show a memory advantage for real-world objects relative to simple color stimuli, whereas healthy controls did under low memory load. In contrast, despite overall impaired performance, AD patients exhibited preserved benefits from perceptual grouping with Kanizsa figures. Together, these findings suggest that high-level top-down modulation supporting VWM performance may be compromised in AD, whereas low-level perceptual organization processes remain relatively intact. This dissociation indicates that cognitive impairments in AD arise at multiple processing levels and likely reflect the differential contributions of distinct cognitive and neural mechanisms.