This is a prospective, two-arm, parallel-group randomized controlled trial conducted at two clinical sites of Semmelweis University: the Department of Geriatrics and Nursing Science, and the Department of Rehabilitation Medicine.
A distinctive feature of the design is that all participants undergo an observation period of equal length under treatment as usual before randomization, so that each participant serves as their own control for the pre-intervention period. This allows the change observed during the intervention period to be distinguished from time-dependent processes occurring during hospitalization itself. This design was chosen because neither a waiting-list control nor a no-treatment condition was considered ethically acceptable in this population.
Participants are enrolled after approximately two weeks of hospitalization (T0). A two-week observation period under usual care follows, during which a single resting heart rate variability recording is obtained. The T1 assessment is conducted at the end of this period, followed by randomization and three intervention sessions delivered over two weeks. The T2 assessment follows the intervention period. No follow-up assessment is conducted.
The two arms differ only in the processing route. The virtual reality arm delivers the natural environment as bottom-up perceptual input via a head-mounted display, using proprietary 360-degree videos recorded from a fixed tripod perspective at three locations near Budapest. The videos contain no narration or added music, only the natural soundscape of the location. The guided imagery arm delivers the same content as an internally generated, top-down process, using a standardized audio recording that begins with a brief breathing relaxation followed by the motif text. Both arms use identical standardized symbolic nature motifs (meadow, stream, mountain) drawn from the motif repertoire of Katathym Imaginative Psychotherapy. The design therefore does not compare an active intervention with a passive control, but two content-equivalent interventions that differ in their processing pathway.
Two primary outcomes are specified. The primary clinical outcome is the change in anxiety symptoms between T1 and T2. The primary mechanistic outcome is RMSSD recorded during the intervention sessions, computed from a five-minute artifact-free window in both arms. Heart rate variability is recorded in three contexts: once at rest during the observation period, during each intervention session, and during neuropsychological testing at each assessment point.
Because hospitalized older adults frequently present with multimorbidity and complex medication regimens, clinical background variables that may affect autonomic regulation and cognitive performance are systematically recorded, including pacemaker status, sympatholytic and psychotropic medication, endocrine conditions, and clinically relevant laboratory abnormalities.
The protocol was prepared in accordance with the SPIRIT 2025 Statement. Registration was performed retrospectively, after enrollment of the first participant. The trial design, including all primary and secondary outcome measures and the statistical analysis plan, was finalized and approved by the research ethics committee before enrollment began, and registration preceded any analysis of outcome data.
