The effect of STH on depression and anxiety has been the subject of many studies. These include some meta-analyses as well as longitudinal studies.
- A meta-analysis of the effects of gardening on human health found ‘positive influences of gardening were particularly evident on patients and horticultural therapy users’. It covered 22 studies comprising 76 comparisons between control and treatment groups. 12 were horticultural therapy studies. The studies reported a wide range of health outcomes, such as reductions in depression, anxiety, and body mass index, as well as increases in life satisfaction, quality of life, and sense of community. [Soga M. and others, (2017). Gardening is beneficial for health: A meta-analysis. Preventive Medicine Reports. 5, 92-99 https://doi.org/10.1016/j.pmedr.2016.11.007]
- A meta-analysis found that mean depression scores were significantly lower for the elderly people who participated in HT programs than for those who did not. More significant effects were found for those aged 75+ and in studies involving more than 20 participants. There were 608 subjects involved in the 13 studies with sample sizes ranging from 6 to 150. Of the 13 studies, 7 were ‘quasi-experimental’ and 6 were RCTs. The studies involving RCTs found significantly larger effects. [Zhang Y.W., Wang J., & Fang T.H. The effect of horticultural therapy on depressive symptoms among the elderly: A systematic review and meta-analysis Front Public Health. 2022 Aug 24;10:953363. doi: 10.3389/fpubh.2022.953363 ]
- Clinically depressed persons suffer from impaired mood and distortion of cognition. This study assessed changes in depression severity and perceived attentional capacity of 18 clinically depressed adults during a 12-week therapeutic horticulture program. Participants were assessed at baseline, after 4 and 8 weeks, immediately after the intervention (12 weeks), and at a 3-month follow-up. Clinically relevant improvements in depression were found in 72% of the cases from pre-test to post-test. The greatest change in scores occurred in the initial weeks of the intervention and the reduction remained significant and clinically relevant at the 3-month follow-up. The study concluded that ‘Therapeutic horticulture may decrease depression severity and improve perceived attentional capacity by engaging effortless attention and interrupting rumination’. [Therapeutic horticulture in clinical depression: a prospective study – Gonzalez et al, 2009 – Res Theory Nurs Pract. 2009;23(4):312-28.]
- The effect of horticultural therapy on psychosocial health in older nursing home residents showed significant improvements in depression and loneliness. The study followed 10 residents of a home in Taiwan who took part in a 10-week programme of 1.5-hour sessions. They were tested before, after, and at weeks 5 and 10 of the programme, using combined quantitative and qualitative measures. Four categories emerged from the qualitative data content analysis: social connection, anticipation and hope, sense of achievement, and companionship. [Chen, Y-M, Ji, J-Y, (2015). Effects of Horticultural Therapy on Psychosocial Health in Older Nursing Home Residents: A Preliminary Study. Journal of Nursing Research. 23(3) 167-171.]