Mental Health

A Structured Forest Therapy Intervention Enhancing the Nature Connection, Mood States, and Satisfaction with Life of U.S. Veterans with PTSD: A Pilot Study
Forest therapy has gained increasing attention as an outdoor therapeutic intervention for individuals with various health challenges. However, its impact on nature connection, mood states, and life satisfaction among veterans with posttraumatic stress disorder (PTSD) remains underexplored. This pilot study investigated the outcomes of a structured forest therapy intervention for U.S. veterans with PTSD using a one-group pretest-posttest design. A total of thirty-five participants (N = 35) were recruited over multiple years through a convenience sampling approach during the one-day nature camp programs for smaller groups of veterans (n = 5, on average per group). Each group engaged in a guided one-hour forest therapy walk which incorporated a standard sequence of mindfulness-based invitations on a quarter-mile long natural dirt trail in a midwestern U.S. region forest. The intervention outcomes were measured using a questionnaire that included the Connectedness to Nature Scale, Profile of Mood States, and Satisfaction with Life Scale, before and after the intervention. A Wilcoxon signed-rank test was used to compare differences in the outcomes of the intervention. The results revealed that participants reported a stronger sense of nature connection. Negative mood states, including anxiety, depression, anger, fatigue, and confusion, decreased significantly, while the positive mood state of vigor showed a notable increase. Life satisfaction was significantly enhanced following the intervention. These findings underscore several substantial benefits of structured forest therapy for improving psychological nature connection, mood, and life satisfaction in veterans with PTSD. The study provides evidence-based support for implementing structured nature immersion interventions for similar populations.

Gil, N., Kim, J., Kim, J. G., Vogt, C., Conway, T., & Bast, K. (2025, September 19). A structured forest therapy intervention enhancing the nature connection, mood states, and satisfaction with life of U.S. veterans with PTSD: A pilot study. Journal of Veterans Studies. https://journal-veterans-studies.org/articles/10.21061/jvs.v11i2.746

Effects of Plant-Emitted Monoterpenes on Anxiety Symptoms: A Propensity-Matched Observational Cohort Study.
Immersive experiences in green areas, particularly in forests, have long been known to produce beneficial effects for human health. However, the exact determinants and mechanisms leading to healthy outcomes remain to be elucidated. The purpose of this observational cohort study was to investigate whether inhaling plant-emitted biogenic volatile compounds, namely monoterpenes (MTs), can produce specific effects on anxiety symptoms. Data from 505 subjects participating in 39 structured forest therapy sessions at different Italian sites were collected. The air concentration of monoterpenes was measured at each site. STAI state questionnaires were administered before and after the sessions as a measure of anxiety. A propensity score matching analysis was then performed, considering an above-average exposure to inhalable air MTs as the treatment. The estimated effect was −1.28 STAI-S points (95% C.I. −2.51 to −0.06, p = 0.04), indicating that the average effect of exposure to high MT air concentrations during forest therapy sessions was to decrease anxiety symptoms.

Donelli D, Meneguzzo F, Antonelli M, et al. Effects of Plant-Emitted Monoterpenes on Anxiety Symptoms: A Propensity-Matched Observational Cohort Study. Int J Environ Res Public Health. 2023;20(4):2773. Published 2023 Feb 4. doi:10.3390/ijerph20042773

An integrative review of the evidence for Shinrin-Yoku (Forest Bathing) in the management of depression and its potential clinical application in evidence-based osteopathy

There is growing interest in the idea of integrating Nature Therapies into the multidisciplinary management of complex conditions such as depression. Shinrin-Yoku (Forest Bathing), a practice involving spending time in a forested environment while paying attention to multi-sensory stimuli has been proposed as one such modality.

The objectives of this review were to critically analyse the current evidence base on the efficacy of Shinrin-Yoku for the treatment of depression, and to examine how the findings may reflect and/or inform osteopathic principles and clinical practice. An integrative review of the evidence for Shinrin-Yoku in the management of depression published between 2009 and 2019 was conducted resulting in n = 13 peer-reviewed studies meeting inclusion criteria. Two themes emerged from the literature, the positive effect of Shinrin-Yoku on self-reported mood scores, and physiological changes arising from forest exposure. However, the methodological quality of the evidence is poor and experiments may not be generalisable. Suggestions were made for improving the research base via mixed-method studies in a biopsychosocial framework, and aspects of the research which may be applicable to evidence-based osteopathy were noted.

Doran-Sherlock R, Devitt S, Sood P. An integrative review of the evidence for Shinrin-Yoku (Forest Bathing) in the management of depression and its potential clinical application in evidence-based osteopathy. J Bodyw Mov Ther. 2023;35:244-255. doi: 10.1016/j.jbmt.2023.04.038.

Effects of forest bathing (shinrin-yoku) on serotonin in serum, depressive symptoms and subjective sleep

We previously found that a forest bathing (shinrin-yoku) program significantly reduced the scores for depression, anxiety, anger, fatigue, and confusion and increased the score for vigor in the profile of mood states (POMS) test and showed a potential preventive effect on the depressive status in both males and females. In the present study, we investigated the effects of a forest bathing program on the level of serotonin in serum, depressive symptoms and subjective sleep quality in middle-aged males.

Twenty healthy male subjects aged 57.3 « 8.4 years were selected after obtaining informed consent. These subjects took day trips to a forest park, the birthplace of forest bathing in Japan named Akasawa Shizen Kyuyourin, Agematsu, Nagano Prefecture, and to an urban area of Nagano Prefecture as a control in June 2019. On both trips, they walked 2.5km for 2

hours each in the morning and afternoon on Saturday and Sunday, respectively. Blood was sampled in the afternoon before and after each trip. Concentrations of serotonin and lactic acid in serum were measured. The POMS test and a questionnaire for subjective sleep quality were conducted before and after the trips. Ambient temperature and humidity were monitoring during the trips.

The forest bathing program significantly increased level of serotonin in serum, and significantly increased the score for vigor and decreased the score for fatigue in the POMS test. The forest bathing program also improved the sleepiness on rising and feeling refreshed (recovery from fatigue) in the Oguri-Shirakawa-Azumi sleep inventory MA version (OSA-MA).

Taken together, the present study suggests that forest bathing may have potential preventive effects on depression (depressive status).

Li Q, Ochiai H, Ochiai T, Takayama N, Kumeda S, Miura T, Aoyagi Y, Imai M. Effects of forest bathing (shinrin-yoku) on serotonin in serum, depressive symptoms and subjective sleep quality in middle-aged males. Environ Health Prev Med. 2022;27:44. doi: 10.1265/ehpm.22-00136. PMID: 36328588; PMCID: PMC9665960.

The influence of forest therapy camp on depression in alcoholics.

The objective of this study is to evaluate the effect of a forest experience on the levels of depression of alcoholics. Prior to the study, 92 alcoholics were divided into treatment and control groups. During the summer of 2009, the treatment group participated in a series of forest therapy programs, while the control group followed their normal daily routines. Both groups were re-tested upon completion of the program by the treatment group and the depression levels compared. There was a significant improvement in the depression level of alcoholics who had participated in the forest camp program (treatment group). Those participants in their 40s who had severe levels of depression at the beginning of the program showed the most significant improvement during the program experience. The forest therapy camp experience can considerably reduce and ameliorate the depression levels of alcoholics.

Shin WS, Shin CS, Yeoun PS. The influence of forest therapy camp on depression in alcoholics. Environ Health Prev Med. 2012 Jan;17(1):73-6. doi: 10.1007/s12199-011-0215-0. Epub 2011 Apr 19. PMID: 21503628; PMCID: PMC3258312.

Effects of Urban Forest Therapy Program on Depression Patients

Depression is a common serious mental health condition that can have negative personal and social consequences, and managing it is critical for treating depression patients. Forest therapy is emerging as a promising non-pharmacological intervention to improve mental health. However, although the effectiveness of forest therapy programs using forests far from the city has been proven, it is not well known that urban forests can be easily accessed in daily life. Therefore, this study aimed to examine the effects of an urban forest therapy program on depression symptoms, sleep quality, and somatization symptoms of depression patients.

A total of 47 depression patients participated in this study (22 in the urban forest therapy program group and 25 in the control group). The Beck Depression Inventory (BDI), the Hamilton Rating Scale for Depression (HRSD), the Pittsburgh Sleep Quality Index (PSQI), and the Patient Health Questionnaire-15 (PHQ-15) were administered to each participant to assess the effects of the urban forest therapy program. The results of this study revealed that depression patients in the urban forest therapy program had significantly alleviated depression symptoms and improved sleep quality and somatization symptoms compared to the control group. In conclusion, this study demonstrates the possibility that the urban forest therapy program could be used as an effective non-pharmacological treatment to alleviate depression disorder.

Yeon PS, Kim IO, Kang SN, Lee NE, Kim GY, Min GM, Chung CY, Lee JS, Kim JG, Shin WS. Effects of Urban Forest Therapy Program on Depression Patients. Int J Environ Res Public Health. 2022;20(1):507. doi: 10.3390/ijerph20010507.