Nature Based Intervention

Within the depth-psychology and allied health corpus, Nature Based Intervention (NBI) occupies an ambiguous but increasingly consequential position. The literature clusters principally around Annerstedt and Währborg’s 2011 systematic review, which taxonomises NBI under the umbrella term ‘nature-assisted therapy’ (NAT) and distinguishes three principal modalities: horticultural therapy, wilderness therapy, and unspecified nature-contact programmes. The corpus reveals a persistent empirical tension: while theoretical frameworks — notably Kaplan’s attention restoration theory, Ulrich’s biophilia hypothesis, and the environmental psychology tradition — provide compelling rationales, the evidentiary base remains methodologically heterogeneous, beset by small samples, outcome-measure inconsistency, and the near-impossibility of blinding. Annerstedt and Währborg document significant positive outcomes across dementia, substance abuse, mood disorders, and acquired brain injury, yet are candid that pooled effect-size estimates are largely unachievable given intervention heterogeneity. Bowen and Neill’s meta-analysis of adventure therapy (a wilderness-proximate modality) reports a moderate short-term effect (g = .47) with long-term maintenance, lending the sub-field its strongest quantitative footing. Bettmann’s 2025 dose-response synthesis advances the field further by disaggregating exposure quantity from intervention type. The theoretical stakes concern whether nature functions as a primary therapeutic agent or merely as a restorative adjunct that amplifies conventional psychotherapy — a question the corpus leaves productively unresolved.

In the library 10 passages

natural spaces, gardening, and exposure to and interaction with natural environments are recognised as health-promoting settings, little is understood about the use of nature contact in treatment and rehabilitation for individuals experiencing ill health.

This passage frames the central problem of the NBI field: while nature’s general health benefits are acknowledged, the therapeutic application of nature contact to clinically ill populations remains under-researched and methodologically underdeveloped.

Annerstedt, Matilda, Nature-assisted therapy: Systematic review of controlled and observational studies, 2011thesis

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when NAT has been compared to indoor institutional treatment, it has been reported that the very act of moving patients outside has a large effect, something that would also support a theory of nature as beneficial itself, or at least bolstering any other therapy.

This passage advances the pivotal theoretical claim that nature may function as an independent therapeutic agent, not merely as a contextual vehicle for existing therapeutic modalities.

Annerstedt, Matilda, Nature-assisted therapy: Systematic review of controlled and observational studies, 2011thesis

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by implementing more rigorous or adequate research methods with proper quality assessment of the subject of NAT, the use of nature in therapy and rehabilitation might prove to be an efficient alternative in health care for varied states of ill health (mainly psychiatric diagnoses).

Annerstedt and Währborg conclude that NAT holds genuine clinical promise for psychiatric conditions but that this promise is contingent upon methodological upgrading of the evidence base.

Annerstedt, Matilda, Nature-assisted therapy: Systematic review of controlled and observational studies, 2011thesis

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Five studies reported outcomes of NAT on populations with dementia, four of them showing improvements… For alcoholism and other substance abuse the results were significantly positive in five studies.

This passage maps the diagnostic reach of NAT, demonstrating significant positive outcomes across dementia, substance abuse, mood and anxiety disorders, and acquired brain injury, establishing the intervention’s breadth of application.

Annerstedt, Matilda, Nature-assisted therapy: Systematic review of controlled and observational studies, 2011thesis

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The short-term effect size for adventure therapy was moderate (g =.47) and larger than for alternative (.14) and no treatment (.08) comparison groups. There was little change during the lead-up (.09) and follow-up periods (.03) for adventure therapy, indicating long-term maintenance of the short-term gains.

Bowen and Neill’s meta-analysis provides the most robust quantitative support for wilderness-based NBIs, demonstrating a moderate short-term effect that is meaningfully maintained over follow-up periods.

Bowen, Daniel J., A Meta-Analysis of Adventure Therapy Outcomes and Moderators, 2013thesis

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This review was mainly concerned with horticultural therapy (implying that the therapy was directed towards a pre-defined clinical condition), rather than therapeutic horticulture (more generally directed towards improving well being, not always with a defined clinical goal).

This passage establishes the conceptual taxonomy within NBI, distinguishing clinically-directed horticultural therapy from the broader wellness orientation of therapeutic horticulture, a distinction with significant implications for outcome measurement.

Annerstedt, Matilda, Nature-assisted therapy: Systematic review of controlled and observational studies, 2011supporting

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Outcomes can broadly be categorised to be of curative, rehabilitative, supportive, or enrichment character. Because of the wide range of programmes using NAT for a wide range of outcome goals it shou[ld be noted]

This passage introduces a four-category outcome framework — curative, rehabilitative, supportive, enrichment — that reflects the heterogeneity of NBI goals and the consequent difficulty of cross-study comparison.

Annerstedt, Matilda, Nature-assisted therapy: Systematic review of controlled and observational studies, 2011supporting

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Because of the heterogenic character of interventions, outcome measures, and of studies examined we were not able to pool our results and generalise any estimate of effect size, but preferred to present our findings in tables and discuss the results.

The authors acknowledge that intervention heterogeneity prevents meta-analytic pooling, a candid admission that identifies the fundamental methodological limitation constraining the NBI evidence base.

Annerstedt, Matilda, Nature-assisted therapy: Systematic review of controlled and observational studies, 2011supporting

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Two unique meta-analyses were conducted based on the extracted pre and post nature exposure data and differentiated by the populations assessed. One analysis measured the change in adults diagnosed with mental illness and the other measured the change in adults with symptoms of mental illness.

Bettmann’s 2025 synthesis advances NBI research by disaggregating population severity — diagnosed mental illness versus symptomatic presentation — thereby introducing dose-response precision into the evaluation framework.

Bettmann, Joanna Ellen, A Systematic Review and Meta-Analysis on the Effect of Nature Exposure Dose on Adults with Mental Illness, 2025supporting

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Ulrich RS. Biophilia, biophobia, and natural landscapes… Kaplan S, Kaplan R. The experience of nature: a psychological perspective… Hartig T, Evans GW, Jamner LD, Davis DS, Gärling T. Tracking restoration in natural and urban field settings.

The reference list situates NAT within its theoretical lineage — biophilia, attention restoration theory, and restorative environment research — identifying the foundational frameworks that the NBI literature inherits and applies.

Annerstedt, Matilda, Nature-assisted therapy: Systematic review of controlled and observational studies, 2011aside

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