Mindfulness-Based and Forest Bathing Interventions for Older Women With Treated Arterial Hypertension

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).