Effects of Virtual Reality-Based Horticultural Intervention for Older Adults With Subthreshold Depression in Nursing Homes

The Center for Epidemiological Surveys Depression Scale (CES-D) was developed by Rirodiff at the National Institute of Mental Health in the United States. It is designed for screening depressive symptoms in older adults, comprising 20 items. Each question assesses one symptom, covering 20 distinct symptoms in total. The total score ranges from 0 to 60 points. A score ≤15 indicates no depressive symptoms, 16-19 suggests possible depressive symptoms, and ≥20 confirms depressive symptoms. The Cronbach's alpha coefficient for the Chinese population is 0.90. It is one of the most commonly used subthreshold depression epidemiological survey tools, with existing studies defining CES-D ≥16 as subthreshold depression.

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The Montreal Coanitive Asessment Scale,developed by Nasreddine in 2004 to assess participants'general cognitive function, covers eight areasof cognitive assessment, including visuospatial and executive function, naming, memory, attention, speech, abstraction, delayed recall, andorientation. The Changsha version of the Montreal Cognitive Assessment Scale was used in this study, and its Cronbach's a coeficient was 0.846,retest reliability was 0.974, and investigator reliability was 0.969. The score of the Montreal Cognitive Assessment Scale ranges from 0 to 30points. The higher the score,the better the cognitive function ofthe study subjects. The iliterate group s13, the primary school group s19 and thejunior high school and above group s24 can be judged as impaired cognitive function to correct the bias caused by education level.

The self-rating anxiety scale (SAS) was designed and developed by Zung in the United States in 1971 to assess the severity of anxiety symptoms in individuals. It demonstrates good reliability and validity, with a split-half reliability coefficient of 0.696, test-retest reliability of 0.777, and internal consistency of 0.82. Additionally, it exhibits good construct validity . The scale comprises 20 items, with items 5, 9, 13, 17, and 19 scored in reverse. The scale employs a 1-4 rating scale (1 = never or rarely; 2 = a small portion of the time; 3 = a considerable portion of the time; 4 = most or all of the time). Individuals complete the scale based on their experiences during the past week. The total score is multiplied by 1.25, rounded to the nearest whole number to obtain a standardized score, which serves as the statistical indicator. A higher standardized score indicates more severe anxiety levels

The General Self-Efficacy Scale (GSES), developed by Schwarzer et al , was used. It consists of 10 items rated on a 4-point Likert scale, ranging from 1 (strongly disagree) to 4 (strongly agree). Higher total scores indicate higher levels of self-efficacy. In this study, the Cronbach α coefficient was 0.81.

This study employed the Pittsburgh Sleep Quality Index (PSQI) developed by Buysse et al. in 1989 to assess patients' sleep quality over the preceding month. The 19-item questionnaire comprises seven components: subjective sleep quality, sleep onset latency, sleep duration, sleep efficiency, sleep disturbances, hypnotic medication use, and daytime functioning. The total score ranges from 0 to 21, with higher scores indicating poorer sleep quality. The Cronbach's alpha coefficient for this scale is 0.85.

System Usability Scale (SUS) Developed by Brooke et al., the scale used in this study is the Chinese version of the System Usability Scale translated and revised by Chinese scholars including Li Yongfeng. This scale is unidimensional and consists of 10 items. It employs a 5-point Likert scale, with scores ranging from 1 ("Strongly Disagree") to 5 ("Strongly Agree"). Positive items (Items 1, 3, 5, 7, 9) are scored positively: Actual item score = Item rating - 1. Negative items (Items 2, 4, 6, 8, 10) are scored negatively: Actual item score = 5 - Item rating. If an item is left blank, it is assigned a score of 3. The total scale score = sum of all item scores × 2.5. The scale has a maximum score of 100 points, with scores >60 considered usable, 70 considered good, ≥80 considered excellent, and ≥90 considered outstanding. The Cronbach's alpha coefficient for this scale is 0.91.

The Simulator Sickness Questionnaire(SSQ) developed by Kennedy et al. in 1993, is a widely used tool for assessing the subjective severity of simulator sickness symptoms. The SSQ consists of pre- and post-experiment sections. The pre-experiment section employs the Pensacola Motion Sickness Questionnaire (MSQ) to gather information about participants' current physical condition and prior simulator experience. The post-experiment section measures symptom severity on a four-point scale (0-3) for each symptom. SSQ items can be grouped into three factors: nausea (e.g., sweating, difficulty concentrating, gastric awareness), eye movement disturbances (e.g., headache, eye fatigue, blurred vision), and disorientation (e.g., head fullness, dizziness with eyes open/closed, vertigo). The SSQ can be scored in two ways: (1) Calculate the score for each factor by summing the scores of all relevant items (each factor includes 7 items), with a score range of 0-179.5

The Immersion Presence Questionnaire (IPQ) was employed to evaluate users' sense of immersion in the experience. Developed by Schubert et al., this questionnaire was subsequently translated into Chinese and validated for reliability and validity by Liang Jiahui et al. The results demonstrated its strong reliability and validity, with a Cronbach's α coefficient of 0.82. The Chinese version comprises 13 items organized into three dimensions: spatial presence (Items 2, 3, 9), involvement (Items 1, 6, 10), and realism (Items 4, 5, 8, 11, 12, 13). Item 7 reflects overall presence. Each item employs a 7-point Likert scale ranging from -3 to 3 points, with items 10 and 12 reverse-scored. The total score ranges from -39 to 39 points, where a higher score indicates a better sense of presence experience in the virtual reality environment.

Item 7 reflects overall presence. Each item uses a 7-point Likert scale ranging from -3 to 3 points, with items 10 and 12 reverse-scored. The total score rang