This systematic review and meta-analysis aimed to summarize the effects of forest therapy on depression and anxiety using data obtained from randomized controlled trials (RCTs) and quasi-experimental studies. We searched SCOPUS, PubMed, MEDLINE(EBSCO), Web of science, Embase, Korean Studies Information Service System, Research Information Sharing Service, and DBpia to identify relevant studies published from January 1990 to December 2020 and identified 20 relevant studies for the synthesis. The methodological quality of eligible primary studies was assessed by ROB 2.0 and ROBINS-I. Most primary studies were conducted in the Republic of Korea except for one study in Poland. Overall, forest therapy significantly improved depression (Hedges’s g = 1.133; 95% confidence interval (CI): −1.491 to −0.775) and anxiety (Hedges’s g = 1.715; 95% CI: −2.519 to −0.912). The quality assessment resulted in five RCTs that raised potential concerns in three and high risk in two. Fifteen quasi-experimental studies raised high for nine quasi-experimental studies and moderate for six studies. In conclusion, forest therapy is preventive management and non-pharmacologic treatment to improve depression and anxiety. However, the included studies lacked methodological rigor and required more comprehensive geographic application. Future research needs to determine optimal forest characteristics and systematic activities that can maximize the improvement of depression and anxiety.

This study aimed to examine the psychological effects of forest activities in a campus forest. A pre-test and post-test control group design was employed to evaluate the psychological effect of forest activities in a campus forest. A total of 38 participants participated in this study (19 in the forest activities group; 19 in the control group). The Profile of Mood State (POMS) questionnaire, the Concise Measure of Subjective Well-Being (COMOSWB), and the modified form of the Stress Response Inventory (SRI-MF) were administered to each participant to assess psychological effects. This study revealed that participants in the forest activities intervention group had significantly positive increases in their mood, stress response, and subjective well-being, comparing with those of control group participants who did not partake in any forest activities. In conclusion, the implementation of forest activities in a campus forest is an efficient strategy to provide psychological well-being benefits to college students.

The study aimed to investigate the psychological and physiological effects of forest therapy programs on adolescents under probation. Fifty probationary teenagers from the Ministry of Gyeonggi Justice Compliance Support Center participated in the study. The study explored the effectiveness of a nonrandomized control group pretest–posttest design forest therapy program. The forest therapy program was conducted for two days and one night for the experimental groups (N = 33), who participated in the forest therapy program, and the control group (N = 17), who received two days of attendance center orders program in the lecture room of the Ministry of Gyeonggi Justice Compliance Support Center. As a result, adolescents under probation who participated in forest therapy programs had a beneficial effect on psychological well-being (K-WBMMS) and HRV’s HF (high frequency) and LF/HF (A ratio of Low Frequency to High Frequency) compared to those who received the general attendance center orders program. These results support that forest therapy programs play a positive role in the psychological and physiological effects of probationary adolescents and can affect the diversity of rehabilitation programs for probationary adolescents.

This study investigated the effect of mobile-based forest therapy programs on relieving depression to advance non-pharmaceutical treatments for patients with depression. The effects of depression, sleep quality, and physical symptoms were analyzed as measurement indicators to determine the effectiveness of symptom relief in patients with depression. This study used a randomized controlled experiment design. Participants were randomly assigned, and a total of 44 people participated, including 23 in the experimental group and 21 in the control group. The experimental group participated in a mobile-based forest therapy program (participating once a week) for six sessions. As a result of this study, depression patients who participated in the mobile-based forest therapy program conducted in urban forests showed a significant reduction in MADRS (from 21.48 ± 4.05 to 7.13 ± 7.00). In addition, PSQI (from 19.78 ± 7.69 to 14.48 ± 8.11) and PHQ-15 (from 9.87 ± 5.08 to 7.57 ± 5.03) were also found to significantly improve symptoms. This suggests that forest-therapy programs using mobile applications can be applied as non-pharmaceutical interventions to relieve symptoms in patients with depression.

Kim H, et al. J Korean Oncol Nurs. 2010 Aug;10(2):146-155. http://dx.doi.org/10.5388/jkon.2010.10.2.146