Reference
Yang Y, Kim H, Kang M, et al. The effectiveness of nature-based therapy for community psychological distress and well-being during COVID-19: a multi-site trial. Sci Rep. 2023;13(1):22370.
Study Objective
To determine the effectiveness of a therapeutic horticulture program on multiple measures of mental health during the Covid-19 pandemic
Key Takeaway
Nature-based therapy (NBT) programs have significant potential to address and resolve multiple aspects of mental health and psychological well-being.
Design
Quasi-randomized, controlled trial, with participants being assigned to experimental (outdoor) vs control (indoor) groups based, in part, on their level of social-distancing comfort during the Covid-19 pandemic.
Participants
This was a multisite trial across 11 locations in South Korea. Investigators recruited participants (N=291; intervention=192; control=99) from various health- and community-based centers. Mean age was 53.48 years (SD 24.05), and 77.3% of participants were female. Inclusion criteria included at least mild depression or anxiety scores on the Mental Health Screening Tool for Depressive Disorders (MHS:D) or the Mental Health Screening Tool for Anxiety Disorders (MHS:A). See Study Parameters Assessed, below. Investigators excluded participants if they had: (1) mobility problems, (2) communication difficulties, or (3) severe mental illness.
Intervention
Group therapeutic horticulture (TH) programs occurred for 2 hours, 2 times per week for 15 weeks. Trained TH practitioners led the programs, and 85% of the intervention time included direct gardening activities (eg, planting, weeding, mulching, etc), while 15% of the time included other indirect activities in the garden (eg, flower arranging, picnics, making/enjoying herbal tea). The control group experienced other group activities (eg, exercise class, singing, cooking classes, computer-programming classes) with identical frequency. The study occurred from June to November 2022.
Study Parameters Assessed
Investigators collected 7 widely used and validated self-report measures of mental well-being and psychological distress measures at 3 times during the study: pretrial, halfway (week 7), and after completion (week 15). The measures were the:
- MHS:D
- MHS:A
- Core Life Activities scale(CORE)
- Satisfaction With Life Scale (SWLS)
- Mindful Attention Awareness Scale (MAAS)
- Perceived Stress Scale (PSS)
- UCLA Loneliness Scale–Short Form (ULS-8)
In addition, participants completed the Working Alliance Inventory–Short Revised (WAI-SR) at weeks 7 and 15 to assess “Therapeutic Alliance,” the degree to which clients feel trust and other relationship constructs with their therapist, which has been shown to significantly influence positive outcomes of therapy.1
Key Findings
Statistically significant outcomes (P<0.0005) with medium-to-large effect sizes occurred for the TH vs control group for all pre-post psychological well-being/distress variables measured.
Specifically, effect sizes (Cohen d) were medium for the MHS:D (d=0.583), MHS:A (d=0.728), SWLS (d=0.786), MAAS (d=0.645), and ULS-8 (d=0.695), and they were large for the CORE (d=1.002) and PSS (d=0.903).
In addition, all postintervention measures were significantly cross-correlated (|r|>0.5).
Mid-postintervention WAI-SR scores demonstrated significant (P<0.001) moderating effect on all psychological variables, with mostly mild-to-moderate effect sizes (d=0.06–0.6).
Transparency
This study was funded by grants from the [South] Korea National Arboretum R&D Project, the Research Service for Effects Verification of Gardening Program for the Socially Vulnerable project, the Ministry of Education of the Republic of [South] Korea, and the National Research Foundation of [South] Korea. The authors declare there were no competing interests in this study.
Practice Implications & Limitations
Population mental-health concerns increased drastically during and after the global Covid-19 pandemic,2,3 with substantial impacts on personal and community economic and social well-being.4 Quarantine protocols were enacted to address fears of infectious-disease mortality but resulted in loss of both revenue and social interaction, keeping people safe but not healthy in a holistic sense.
Use of outdoor parks and other green spaces increased dramatically during the Covid-19 pandemic, with significant benefits to individual and public mental, physical, and social health.
One way people coped with these drastic social changes is by doing what we have always done in times of challenge: finding solace in nature. Use of outdoor parks and other green spaces increased dramatically during the Covid-19 pandemic, with significant benefits to individual and public mental, physical, and social health.5 Pandemics of the past and the resulting public health issues helped catalyze the inclusion of green spaces in urban design.6
The therapeutic and restorative capacity of being in nature has been well-researched, with multiple meta-analyses showing physiological, psychophysiological, psychological, and social benefits of urban green spaces.7–12
This study demonstrates that NBT—in this case, a community group–based gardening program—can substantially improve mental well-being and reduce psychological distress. Specifically, the outcome measures for depression, anxiety, life engagement/vitality, life satisfaction, mindfulness, perceived stress, and loneliness all improved with the TH program. This occurred not only on an absolute level but also relative to the control condition of other non-TH group experiences, suggesting that something specific about the group gardening experience produced these positive effects.
A secondary finding of this study demonstrated that the group TH experience significantly improved the therapeutic alliance between participants and the TH facilitators, which, in turn, positively moderated the mental well-being and psychological distress outcomes. It is likely that the environmental context of the garden setting facilitated, through restorative and stress-reducing mechanisms, a greater capacity for participants to let down psychological barriers and establish more beneficial connections with facilitators.
As the authors note, this study was slightly limited by the quasi-randomization design, assigning participants to the experimental group vs control group based on their comfort with indoor vs outdoor social distancing during the Covid-19 pandemic. All relevant demographic and prestudy outcome measures were equivalent between groups, so it is likely that this quasi-randomization did not substantially affect study validity. To be completely experimentally valid, however, a repeat of this study with true group randomization could be conducted. In addition, while the experimental TH group experience was standardized across the 11 sites, control-group experiences were widely varied, and results were aggregated for analysis. A more standardized, uniform control-group experience would improve validation when comparing against the experimental TH group.
This study demonstrates that a simple, nature-based group therapeutic horticulture/gardening program has the ability to substantially improve a wide variety of mental well-being and psychological distress measures. Such NBT programs should be considered as integrative, adjunctive therapies for reducing the burdens of individual and population mental health concerns.
Conflict of Interest Disclosure
There are no conflicts of interest associated with this report.
