Comparison of Gaze Behavior During a Visual Search Task in a Virtual Reality Environment Between Individuals With Alzheimer's Disease and Healthy Older Adults.

INTRODUCTION: Decline in spatial attention is a core feature of Alzheimer's disease (AD) that directly impairs everyday visual search behavior, such as locating items during shopping. Japan's rapidly aging population has led to a growing prevalence of dementia, with AD being the most common subtype. The use of virtual reality (VR) enables standardized cognitive assessment in ecologically valid settings. METHODS: A total of 25 individuals with AD and 30 healthy controls (HC) aged 65 years or older performed a visual search task presented via a head-mounted display (HMD; VIVE Pro Eye, HTC Corporation, Taoyuan, Taiwan) showing a VR simulation of a supermarket beverage section captured with a 360° camera. Participants were instructed to locate a lemon tea product within 30 seconds. Eye movements were recorded binocularly at 120 Hz. The viewing field was divided into a 48×48 grid; fixation duration and proportion in the central region (columns 20-27, rows 24-33) were extracted and compared between groups using independent samples t-tests. The chi-square test of independence was used to compare the rate of successful target identification. RESULTS: Compared with HC, the AD group showed significantly longer central fixation duration (11.63 s vs. 6.66 s, p = .009) and a higher central fixation proportion (38.55% vs. 22.06%, p = .009). None of the AD participants identified the target within the time limit, compared with 15 of 30 (50%) HC participants (χ²(1) = 17.19, p < .001, φ = -0.559). CONCLUSION: Individuals with AD demonstrated a restricted gaze pattern characterized by central fixation bias during VR-based visual search, reflecting impaired exploratory eye movements and narrowed visual search range. These findings suggest that VR-based gaze analysis may serve as a useful tool for evaluating functional visual cognition in AD and that consideration of these gaze characteristics may inform the design of more accessible retail environments and support daily functioning and social participation.