No abstract

Introduction: Interventions aimed at addressing subthreshold depression (StD) are important to prevent the onset of major depressive disorder. Our video playback application (SPSRS) is designed to reduce depressive symptoms by presenting positive words in videos, shedding new light on the treatment of StD. However, no randomized controlled trial (RCT) has utilized this video playback application for the treatment of individuals with StD. Therefore, a pilot RCT was designed to determine the feasibility of a full-scale trial. We herein present a study protocol for investigating the utility of a video playback application intervention for individuals with StD. Methods: This 5-week, single-blind, 2-arm, parallel-group, pilot RCT will determine the effectiveness of the video playback application by comparing individuals who had and had not been exposed to the same. A total of 32 individuals with StD will be randomly assigned to the experimental or control group at a 1:1 ratio. The experimental group will receive a 10-minute intervention containing the video playback application per day, whereas the control group will receive no intervention. The primary outcome will include changes in the Center for Epidemiologic Studies Depression Scale score after the 5-week intervention, while secondary outcomes will include changes in the Kessler Screening Scale for psychological distress and the generalized anxiety disorder 7-item scale score after the 5-week intervention. Statistical analysis using linear mixed models with the restricted maximum likelihood estimation method will then be performed. Discussion: This pilot RCT will have been the first to explore the utility of SPSRS application interventions that display positive words in videos for individuals with StD. The results of this pilot trial are expected to help in the design and implementation of a full-scale RCT that investigates the effects of SPSRS applications among individuals with StD. Trial registration: ClinicalTrials.gov Identifier: NCT04136041

Virtual reality (VR) has been applied to several elds such as entertainment, education, and medicine in recent years. VR is characterized by a high sense of immersion, which can be represented by the attention allocation from the real world to the virtual space. Although a high degree of attention allocation is significant in VR technology, most existing evaluation methods of VR applications are based on subjective questionnaires. Thus, quantitative and objective VR application evaluation methods are needed to realize advanced VR applications. In this study, we adopted a probe stimulus method to evaluate the attention allocation quantitatively and objectively in VR technology. Ten young adult participants underwent an auditory oddball task while they experienced VR content. The amount of attention directed to the VR content could be quantied based on the decrease in the event-related P300 wave response in the case of the oddball task. The participants watched two-dimensional and three-dimensional VR contents on a liquid crystal display and a headmounted display, respectively, while brain activity was recorded in the form of electroencephalographic signals. A total of 230 probe stimuli at 1800 Hz (standard stimulus), 2000 Hz (target stimulus), and 500 Hz (deviant stimulus) were presented randomly via an earphone for 70 ms at 1000-ms intervals at the fractions of 70, 15, and 15%, respectively. Additionally, the reaction time and false reaction rate during the oddball task were measured as behavioral measures, and a questionnaire was used for subjective evaluation after the task. Based on a comparison of the subjective measure, behavioral measure, and amplitudes of P300 measured with the target stimulus from Pz and deviant stimulus from Cz, we found that attention allocation to the VR content can be quantitatively estimated using the amplitude of P300 for the deviant stimulus. These results suggest that the proposed method involving event-related potentials can be used as an indicator for attention allocation while watching VR content.