VR Relaxation in Older Adults With Mental Illness

Evaluated with the German Version of the Positive and Negative Affect Schedule (PANAS; Breyer \& Bluemke, 2016; Krohne et al., 1996; Watson et al., 1988). The PANAS is a 20 item self-report questionnaire assessing two dimensions of affect, positive affect (PA) and negative affect (NA), with 10 items for each dimension. Since it is allowed to adapt PANAS instructions depending on the research purpose (Breyer \& Bluemke, 2016), we ask patients to refer to the present moment when evaluating each adjective on a 5-point Likert scale (1 = 'not at all' to 5 = 'extremely'). In a representative sample from the GESIS Panel 2014, the German version of the PANAS had good psychometric properties, such as high internal consistency (α = 0.86) (Breyer \& Bluemke, 2016).

Measured with a single-item VAS, which we developed for our study based on the Numeric Stress Rating Scale (NSRS; Lee, 2010, as cited in Tan et al., 2021). In an RCT on VR stress management for inpatients with mental disorders, the NSRS was used to assess immediate changes in subjective stress pre- and post-sessions. Test-retest reliability was indicated by significant correlations between waitlist control group scores (Tan et al., 2021). The VAS item was translated to German and adapted for the purpose of our study. Patients rate their momentary perceived stress on a scale from 0 = 'no stress' to 10 = 'extreme stress' (Tan et al., 2021). It is presented as a horizontal line with no calibration marks apart from the two labeled endpoints. Numeric mean scores for T0 and T1 are obtained, with lower scores indicating lower stress levels.

Measured using a single-item VAS, which we developed and translated for this study based on previous studies examining the effects of VR relaxation in individuals with mental illness (Riches, Nicholson, et al., 2023; Tan et al., 2021). The patients are asked to mark on a scale how relaxed they feel at that moment. The scale ranges from 0 = 'not relaxed at all' to 10 = 'very relaxed' and is presented as a horizontal line with no calibration marks apart from the two labeled endpoints. Numeric mean scores for T0 and T1 are calculated, with higher scores indicating a higher momentary relaxation.

Assessed using a single-item VAS. Patients are asked to mark on the VAS how well they feel at that present moment. The scale is presented as a horizontal line with two endpoints (0 = 'not well at all'; 10 = 'very well') and no marks along the scale. Numeric mean scores are calculated for T0 and T1, with higher values indicating a higher overall well-being.

Drop-out rates are recorded to compare the acceptance of both treatments. Participants are considered as a drop-out, if the VR-based relaxation exercise or the guided dream journey is terminated before the scheduled end after 10 minutes.

Measured with five items, based on the ZUF-8 (Schmidt et al., 1989), which is the German version of the Client Satisfaction Questionnaire (CSQ-8; Attkisson \& Zwick, 1982). The ZUF-8 is commonly used to economically evaluate patient's general satisfaction with psychotherapeutic treatment in stationary settings (Schmidt et al., 1989), but has already been adapted to examine the feasibility of VR relaxation in psychiatric outpatients (Humbert et al., 2023). For our study, three items are excluded due to their lack of suitability for our specific intervention context, five items are retained and slightly rephrased to adapt them to each condition. The response option for each item was adopted from the ZUF-8 (Schmidt et al., 1989).

Assessed with three single-item VAS, ranging from 0 = 'not at all' to 10 = 'very'. The scales were adopted, partly rephrased and translated into German from the study of Riches, Nicholson, et al. (2023) on VR relaxation within acute psychiatric services. Patients rate how helpful they found the (virtual) relaxation exercise (helpfulness), how connected they felt to nature (connectedness to nature) and to what extent they felt that they were actually in the relaxing environment (immersion).

Measured as an indicator for the tolerability of the VR relaxation exercise, measured with the Fast Motion Sickness Scale (FMS; Keshavarz and Hecht, 2011), a valid and brief self-report measure to determine motion sickness in VR (Keshavarz \& Hecht, 2011), immediately after the VR application was terminated. The patients rate the severity of their current motion sickness on a scale from 0 (no motion sickness) to 20 (frank motion sickness).

Measured with the German version of the iGroup Presence Questionnaire (IPQ; Himmels et al., 2023). The IPQ has good psychometric properties (Himmels et al., 2023), was previously used to assess presence in VR-based relaxation interventions (Liszio et al., 2018), and demonstrated its feasibility for measuring sense of presence in a geriatric psychiatric sample (Just \& Lütt et al., 2024). In total, 14 items are rated on a scale from -3 to +3, with varying anchors for each item. The IPQ items are divided into the subscales 'spatial presence,' 'involvement,' and 'realness,' with one additional item measuring 'general presence' (Himmels et al., 2023).