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Efficacy of nature-based therapy for individuals with stress-related illnesses: randomised controlled trial

  • Ulrika Karlsson Stigsdotter (a1), Sus Sola Corazon (a1), Ulrik Sidenius (a1), Patrik Karlsson Nyed (a1), Helmer Bøving Larsen (a2) and Lone Overby Fjorback (a3)...

Stress-related illnesses are a major threat to public health, and there is increasing demand for validated treatments.


To test the efficacy of nature-based therapy (NBT) for patients with stress-related illnesses.


Randomised controlled trial ( ID NCT01849718) comparing Nacadia® NBT (NNBT) with the cognitive–behavioural therapy known as Specialised Treatment for Severe Bodily Distress Syndromes (STreSS). In total, 84 participants were randomly allocated to one of the two treatments. The primary outcome measure was the mean aggregate score on the Psychological General Well-Being Index (PGWBI).


Both treatments resulted in a significant increase in the PGWBI (primary outcome) and a decrease in burnout (the Shirom–Melamed Burnout Questionnaire, secondary outcome), which were both sustained 12 months later. No significant difference in efficacy was found between NNBT and STreSS for primary outcome and secondary outcomes.


The study showed no statistical evidence of a difference between NNBT and STreSS for treating patients with stress-related illnesses.

Declaration of interest


Corresponding author
Correspondence: Sus Sola Corazon, Rolighedsvej 23, 1959 Frederiksberg C, Denmark. Email:
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Efficacy of nature-based therapy for individuals with stress-related illnesses: randomised controlled trial

  • Ulrika Karlsson Stigsdotter (a1), Sus Sola Corazon (a1), Ulrik Sidenius (a1), Patrik Karlsson Nyed (a1), Helmer Bøving Larsen (a2) and Lone Overby Fjorback (a3)...
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Environmental preference might mediate the benefits of nature-based therapies

Jacob King, Research Associate, Centre for Urban Design and Mental Health
15 August 2018

The benefits of psychotherapies are highly variable between patients, perhaps most notably due to personality types, cultural background and one’s conception of mental ill health, among others (Petronzi & Masciale, 2015). Case in point, many patients consider group psychotherapy unacceptable and others do not consider psychotherapy credible at all. Similar variations are surely also implicated in nature-based psychotherapies (NBTs).

For example, in the first instance, evidence over recent years has increasingly pointed to a benefit to mental health outcomes, from exposure to and use of natural environments, commonly conceived in the literature as ‘urban green spaces’. The causal mechanisms are complex, but usually distilled to; improved exercise and socialisation opportunities, reduced exposure to air and noise pollution, and importantly for NBTs, psychological stress-reduction and attention restoration (Markevych et al., 2017). As well as being evidenced, it is easy to anecdotally see how these non-psychotherapeutic components of NBT – the simple exposure and interaction with one’s natural environment - are mediated culturally, and also by personality and personal environmental preferences inter alia. Between cultures, for example, there is dramatic variation in perceptions of natural environments and understandings of appropriate uses of these spaces (Buijs, Elands, & Langers, 2009). These variations are likely to modulate the causal mechanisms of the green space / mental health benefit.

Secondly, it is reasonable to suggest that these variations in the perceptions of natural environments affect the acceptability, credibility and therefore adherence and completion rates of NBTs. Until now the evidence for green space benefit to mental health outcomes has come largely from observational studies, which demonstrated varied effect sizes, and suggested differences due to quality of environments, perceived safety concerns, among other individual personality and community factors (Gascon et al., 2015).

Stigsdotter and colleagues’ most recent report therefore, which demonstrates non-inferiority of one particular brand of NBT for stress-related mental illnesses compared to a more mainstream CBT, is to be welcomed (Stigsdotter et al., 2018).

While of course randomisation of patients is an essential facet in the production of reliable and valid science, this may have masked a sub-population with complementary personalities and cultural characteristics (etc.) for nature-based psychotherapies. And as authors allude, given equal study withdrawal rates after randomisation, there may well be an equal sub-population with preference of office-based CBT, (perhaps for perceived credibility reasons). The non-inferiority demonstrated in this trial therefore gives us the option that those patients who may be open, and keen on the idea of NBTs may be at greater benefit, may be more adherent, more likely to complete the intervention, and independently receive greater benefit through the causal mechanisms described above. Nature-based therapies therefore might now be considered another option (rather than any kind of replacement) in the tool kit of primary care or mental health services towards addressing the high burden of stress morbidity, especially for those expressing a preference for it.


Buijs, A. E., Elands, B. H. M., & Langers, F. (2009). No wilderness for immigrants: Cultural differences in images of nature and landscape preferences. Landscape and Urban Planning, 91(3), 113-123. doi:

Gascon, M., Triguero-Mas, M., Martínez, D., Dadvand, P., Forns, J., Plasència, A., & Nieuwenhuijsen, M. (2015). Mental Health Benefits of Long-Term Exposure to Residential Green and Blue Spaces: A Systematic Review. International Journal of Environmental Research and Public Health, 12(4), 4354.

Markevych, I., Schoierer, J., Hartig, T., Chudnovsky, A., Hystad, P., Dzhambov, A. M., et al. (2017). Exploring pathways linking greenspace to health: Theoretical and methodological guidance. Environ Res, 158, 301-317. doi:

Petronzi, G., & Masciale, J. (2015). Using personality traits and attachment styles to predict people's preference of psychotherapeutic orientation. Counselling and Psychotherapy Research, 15(4), 298-308. doi:10.1002/capr.12036

Stigsdotter, U. K., Corazon, S. S., Sidenius, U., Nyed, P. K., Larsen, H. B., & Fjorback, L. O. (2018). Efficacy of nature-based therapy for individuals with stress-related illnesses: randomised controlled trial. The British Journal of Psychiatry, 213(1), 404-411. doi:10.1192/bjp.2018.2
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Conflict of interest: None declared

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