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With the ultimate aim of early diagnosis of dementia, a new body balance assessment system with integrated head-mounted display-based virtual reality (VR) has been developed. We hypothesized that people would sway more in anterior-posterior (AP) direction when they were exposed to a VR environment where we intentionally provoked movements in forward and backward directions. A total of 14 healthy older adults (OA) (73.14±4.26 years) and 15 healthy young adults (YA) (24.93±1.49 years) were assessed for group differences in sway behavior. Body sway speed in 22 different conditions with and without VR environments was analyzed. Significant differences and large effect sizes were observed in AP sway under the VR environments (OA with P < 0.02; effect size> 0.61, YA with P < 0.003; effect size> 0.72) compared to the baseline condition without the VR environments. In addition, significant differences were found between the two groups in AP sway in all test conditions ( P < 0.01). Our study shows that a VR environment can trigger body sway in an expected direction, which may indicate that it is possible to enhance the sensitivity of balance assessment by integrating immersive VR environments. The result of this study warrants a cross-sectional study in which OA diagnosed with and without dementia are compared on their sway behavior.

Background: Postural sway and saccadic eye movement could be potential biomarkers to diagnose Alzheimer's disease (AD) [1, 2]. We developed a new assessment system to evaluate posture and saccadic eye movement simultaneously in healthy older adults (OA) with visual stimuli of distractors, lower contrast, and stereopsis, which are also considered to be another deficit in people with AD [3][4][5]. We hypothesised that more latency and errors in saccade would be observed in the condition with visual stimuli.Method: 14 healthy older adults (71.9±4.8 years, 7 men / 7 women) joined the experiment after taking Montreal Cognitive Assessment (MoCA). The system consisted of stabilometer (GP-5000, ANIMA Corporation, Japan) and a head-mounted display virtual reality technology (VIVE Pro Eye, HTC Corporation, Taiwan). We measured both posture and eye movement simultaneously in the following test conditions: #1-2) eyesopen and closed without VR, #3-4) pro-and anti-saccade tests in 2D environment, and #5-6) pro-and anti-saccade tests in 3D environment. We developed the 2D environment for the baseline saccade measurement and 3D environment with more visual stimuli [6]. Each test took 60 seconds with 30 saccade trials. Result:The participants achieved MoCA score of 27.5±1.6. We found significant difference in saccade latency between saccade types (mean: P < 0.001, SD: P < 0.001) but less significant difference between VR scenery (mean: P = 0.01, SD: P = 0.42). Moreover, we observed less significant difference in saccade error rate between saccade types (P = 0.07) and between VR scenery (P > 0.77). We did not see significant difference in postural sway (P > 0.05). Conclusion:The results may imply that the healthy OA had sufficient attentional resources to both conduct the saccade tasks and maintain their posture in the designed VR environment with visual stimuli. Further research is required to evaluate the differ-

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BackgroundDementia is becoming a relevant problem worldwide. A simple screening at an early stage will be important to detect the risk of developing dementia. Vestibular dysfunction is likely to be associated with cognitive impairment. Since head-mounted display (HMD) virtual reality (VR) technology has the potential to activate the vestibular function, assessing postural sway with visual stimulation using HMD VR technology could be potentially useful for dementia screening.ObjectiveThe purpose of this study is to evaluate the effect of HMD-based VR visual stimuli on posture in older adults and the relationship between the stimulated body sway behaviors and cognitive performance.MethodUsing a cross-sectional study design, we investigated the effect of an optokinetic design-based room with stripes (OKR) VR environment oscillating forwards and backwards at 23/60Hz. Center of pressure (COP) displacement was measured in older adults aged 65 years and over in the OKR VR environment. The frequency response of COP was compared to the cognitive performance of the Montreal Cognitive Assessment (MoCA).Results20 healthy older adults (70.4 ± 4.9 years; 27.2 ± 1.6 MoCA score) and 3 people with mild cognitive impairment (74.7 ± 4.0 years; 20.3 ± 2.1 MoCA score) were assessed. The results reveal that the oscillating OKR VR environment induced different postural sway in the anterior-posterior direction in the real world. Correlation analysis shows that the cognitive test score was associated with the frequency response of stimulated postural sway in the anterior-posterior direction (frequency Band 1 of 0−0.5Hz related to the visual and vestibular systems: rs = 0.45, P = 0.03).ConclusionOutcomes would suggest that a potential link may emerge between cognition and posture when the HMD-based VR visual stimuli are applied. The simple screening of stimulated postural sway could explain cognitive functioning. Further studies are warranted to clarify the vestibular system and spatial cognitive function more specifically in the proposed assessment system.