This pilot study, conducted by the Department of Social Medicine and Epidemiology, Faculty of Medicine, University of Rijeka, and funded by the University of Rijeka (project no. uniri-iskusni-biomed-23-181), evaluated two adjunctive non-pharmacological interventions - an eight-week Mindfulness-Based Living Course (MBLC) and a guided forest bathing (Shinrin-yoku) program - relative to a non-randomized comparison group, in older women with treated arterial hypertension. The study used a non-equivalent, pre-test/post-test quasi-experimental design; allocation was non-randomized, based on geographic catchment area and registration with community patronage nurses, with first-come, first-served enrollment until recruitment targets were met. A total of 60 women over 60 years of age were planned for enrollment: 20 in the MBLC group, 20 in the forest bathing group, and 20 in a comparison group receiving usual care. The MBLC group attended eight weekly two-hour workshops based on the Mindfulness Association (UK) curriculum, led by certified facilitators in Rijeka. The forest bathing group attended three weekly guided sessions of approximately 120-150 minutes each at a forest site near Delnice, Gorski Kotar, led by an FTHub-certified guide following the Forest Therapy Hub (FTHub) Walk Activities Sequence. The comparison group received no structured intervention. Outcomes were assessed at baseline and immediately after each group's intervention period (approximately 8 weeks for MBLC; approximately 3 weeks for forest bathing; a matched interval for the comparison group). The primary outcome was perceived stress (10-item Perceived Stress Scale). Secondary outcomes included chronic-disease self-efficacy, health-related quality of life, systolic and diastolic blood pressure, heart rate, and serum cortisol. Eligible participants were women over 60 with documented, treated arterial hypertension who gave written informed consent; exclusions included age under 60, inability to participate for the study duration, homelessness, a diagnosed psychiatric condition, cognitive impairment, and alcohol or substance dependence. The study was approved by the Ethics Committee of the University of Rijeka, Faculty of Medicine (Class: 007-08/24-01/70; 22 October 2024) and was conducted January-May 2025 in Rijeka and the Gorski Kotar region, Croatia. The study is being registered retrospectively, after data collection was complete.

Background and rationale: Arterial hypertension (AH) is highly prevalent among older women, in whom blood pressure control is influenced by chronic psychosocial stress and often deteriorates after menopause. Despite effective antihypertensive pharmacotherapy, population-level blood pressure control remains suboptimal, creating a need for feasible, low-risk adjuncts to standard care that support self-management and well-being without replacing medication. Current European Society of Hypertension guidance acknowledges a role for stress-reduction approaches within lifestyle management. Two candidate adjunctive approaches were of interest here: mindfulness-based intervention, which targets attentional regulation, non-judgmental awareness, and self-compassion; and guided forest bathing (Shinrin-yoku), a nature-based intervention thought to act through sensory immersion, attentional restoration, and parasympathetic activation. Comparative evidence on structured mindfulness-based versus forest-based adjuncts in older women with treated hypertension, assessed across psychological, quality-of-life, and physiological outcomes together, remains limited. This pilot study was designed to generate effect-size estimates to inform a future adequately powered trial rather than to provide confirmatory tests of effectiveness.

Objectives: The general objective was to evaluate and compare the effectiveness of two adjunctive non-pharmacological interventions - an eight-week Mindfulness-Based Living Course (MBLC) and a guided forest bathing intervention - relative to a non-randomized comparison group, in improving perceived stress, chronic-disease self-management self-efficacy, health-related quality of life, and selected physiological parameters among older women with treated arterial hypertension, from baseline to follow-up. Specific research questions addressed: (1) whether MBLC or forest bathing produced a greater reduction in perceived stress than the comparison group; (2) whether either intervention produced greater improvement in chronic-disease self-efficacy; (3) whether either intervention produced greater improvement in health-related quality of life; (4) whether either intervention produced more favorable change in blood pressure, heart rate, or cortisol; and (5) whether effects differed between the two active interventions.

Design and allocation: This was a non-equivalent, pre-test/post-test quasi-experimental pilot study with three parallel groups (two intervention groups and one comparison group). Allocation was non-randomized. Randomization was not feasible because the mindfulness workshops and forest bathing sessions were each delivered as a community-based service at fixed sites linked to specific community patronage nurses and required advance scheduling and capacity planning within existing primary-care infrastructure. Participants were therefore allocated pragmatically according to their geographic catchment area and registration with a participating community patronage nurse, and were enrolled consecutively as they expressed interest, on a first-come, first-served basis, until each group's recruitment target was reached.

Setting and timeline: The study was conducted from January 2025 to May 2025. Recruitment and the mindfulness workshops took place in Rijeka, Croatia; the forest bathing sessions took place at a forest site near Delnice, in the Gorski Kotar region. Data were collected at two time points for every participant: baseline (T0) and immediately after completion of that participant's assigned intervention period (T1) - approximately 8 weeks after baseline for the MBLC group and approximately 3 weeks after baseline for the forest bathing group, with a matched elapsed interval used for the comparison group.

Interventions: The MBLC group attended one two-hour workshop per week for eight weeks (16 structured contact hours), delivered by certified mindfulness facilitators using a structured manual. MBLC is a curriculum developed by the Mindfulness Association (United Kingdom) that cultivates present-moment awareness, compassion, and self-compassion, progressing across sessions from attentional and somatic training toward emotion regulation and compassion-based practice. Participants were encouraged to complete approximately 20-30 minutes of daily home practice, supported by guided audio/video recordings and a workbook; home-practice adherence was not formally tracked. The forest bathing group attended three weekly guided sessions of approximately 120-150 minutes, scheduled within a consistent morning window to limit diurnal variation in physiological outcomes, at the same forest site and along the same predefined route (approximately 1.5-2 km) each time. Sessions were led by a guide certified by the Forest Therapy Hub (FTHub) and followed the FTHub Walk Activities Sequence (introduction/arrival, Mechanical Senses, Chemical Senses, Engage/Direct Exposure activities, Txoko sit-spot, and a closing Circle of Incorporation); no structured home practice was assigned between sessions. The comparison group continued routine general-practitioner follow-up and usual antihypertensive management, with no structured attention-control activity.

Outcome assessment: Psychological and quality-of-life outcomes were assessed using validated self-report instruments (detailed in the Outcome Measures section); physiological parameters (blood pressure, heart rate, serum cortisol) were assessed using a validated automated monitor and a single accredited laboratory, with cortisol sampling standardized to a fixed morning window under fasting conditions to limit diurnal variability.

Statistical analysis: Baseline comparability across the three groups will be assessed using the chi-square test for categorical variables and the Kruskal-Wallis test for ordinal variables. The primary and secondary outcomes will each be analyzed using a two-way repeated-measures analysis of variance (group x time), with the group x time interaction as the effect of interest; the post hoc Tukey Honestly Significant Difference procedure will be used to control the family-wise error rate for pairwise comparisons within each analysis. Analyses will be performed in IBM SPSS Statistics v28.0 on a complete-case basis (participants with both T0 and T1 data for the outcome in question).

Ethical considerations and registration status: The study was approved by the Ethics Committee of the University of Rijeka, Faculty of Medicine (Class: 007-08/24-01/70; Reg. no. 2170-1-42-04-3/1-24-12) on 22 October 2024, and was conducted in accordance with the Declaration of Helsinki, the Nuremberg Code, Croatian health and patients' rights legislation, and Regulation (EU) 2016/679 (GDPR). All participants provided written informed consent. This study is being registered after the completion of data collection (retrospective registration).

Inclusion Criteria:

• Woman older than 60 years
• Diagnosed arterial hypertension (pharmacologically treated)
• Signed informed consent form for participation

Exclusion Criteria:

• Age under 60 years
• Inability to participate in the study over a six-month period (e.g., persons planning extended travel or terminally ill patients)
• Without stable housing (homeless individuals)
• Diagnosed psychiatric disorder(s)
• Cognitive impairment
• Alcohol or other substance dependence
• Unsigned consent form for participation