Introduction
Many analyses and reviews have concluded that, at least for some individuals in some
circumstances, exposure to nature can lead to improvements in multiple mental and
physical health parameters and that this applies for both contemplative and adventurous
activities (1–15). Over at least the past 4 decades, countries have trialed a wide
range of public health programs aimed to increase public participation in outdoor
activities, including visits to parks (14–18). At the same time, however, social and
technological changes have created opposing pressures: education, work, and lifestyles
in developed nations have become increasingly urbanized and indoors (19). Perhaps,
as a result, these public health programs have achieved only limited success to date.
This issue is important in public health, since many developed nations are now experiencing
increasing social and economic costs from depression, dementia, obesity, and diabetes
(10–13, 20–22). These diseases are distinct, but correlated across individuals, and
known jointly as chronic disease syndrome (CDS). They are driven partly by genetics
(23), but largely by lifestyle (10–13). Older individuals live longer, in poor health,
but children are also affected (24). Costs include treatments and healthcare, lost
productivity, paid and unpaid carers, and decreased quality of life (QOL) (6, 20–22,
25). In total, these costs may be ~10% GDP for nations with aging populations and
high per capita healthcare expenditure (6, 20–22, 25).
If we could design health programs or interventions that use outdoor nature-based
activities to prevent or treat CDS cheaply and effectively, then that would provide
an opportunity to alleviate substantial individual suffering and to overcome a major
and growing budgetary problem for national governments (26). A wide range of such
programs do exist, under names such as ecotherapies (2), adventure therapies (27),
outdoor adventure interventions (27), ecopsychosocial interventions (13), lifestyle
therapies (28), and green prescriptions (18, 29, 30), but currently, at rather small
scale in global terms. We refer to them here, in aggregate, as nature, eco, and adventure
therapies (NEATs). Here, we identify some obstacles to their success and propose research
and policy changes for more effective implementation.
We suggest that public and private NEAT programs have been too poorly targeted, and
used too small a dose, to prove effective. We propose that this obstacle can be overcome
by designing NEATs that are routinely prescribable as a part of clinical healthcare
systems. We suggest that while there is ample evidence, as outlined above, that nature
exposure and activities can prevent, delay, or alleviate the mental health components
of chronic disease, this has been principally at proof-of-concept level. Dose–duration–response
relationships, necessary to design practical and prescribable NEATs, remain largely
studied (31).
Research to Underpin Policy
To underpin policy changes, we suggest that research is first required on these dose–duration–response
relationships. Short-term effects of NEATs can be measured, for example, through changes
in anxiety and stress, attitudes and behavior, efficacy and productivity, and self-reported
QOL. We should compare effects of NEATs for (a) different mental health conditions
and degrees of severity; (b) different individuals, depending on gender, age, personality,
and circumstances; and (c) different therapy types, intensities, frequencies, length
of each treatment session, and overall duration of the course of treatment.
Research is also required on techniques to trigger changes in patient lifestyles that
continue after an initial prescribed course of NEAT is complete. This requires that
patients perceive an improvement in health and happiness during the prescribed course,
sufficient to motivate them to continue subsequently. This is a similar model to many
physiotherapies and psychotherapies (32, 33). Lifestyle change may require greater
dose and duration than improvement during treatment. This research is social rather
than clinical. The mechanisms are social levers (34), and the measures of success
are behavioral changes, QOL, improved productivity, reduced antisocial behavior, and
reduced use of treatment facilities.
Finally, we need research on how the adoption of NEATs, either alone or in conjunction
with physical therapies and nutrition, may be influenced by cultural traditions and
circumstances. NEATs are limited by cultures and climate (35) as well as by health
budgets (20). Countries with easy access to nature, benign climate, and social acceptability
of outdoor activities for all demographic groups are ideal for NEATs.
Policy Options and Implications
Once courses of treatment have been designed and trialed to provide both short- and
long-term effectiveness, adoption of NEATs will need changes to the institutional
structures of healthcare systems. NEATs meeting criteria for prescription will need
to be defined and described in detail. NEAT treatments and providers will need to
be certified and licensed. Practitioners will need training in diagnosis, prescription,
and evaluation.
Prescribing NEATs through licensed providers involves costs and funding. Currently,
many health insurers recommend low-cost patient-funded or publicly funded outdoor
activities as a preventive measure, but few support prescribable NEATs as therapeutic
measures. Health insurers and government health agencies need to determine what NEATs
they will insure or support and what costs they will fund. Not everyone has health
insurance, so public funding will be needed for those who do not. This is a good public
investment, since NEATs are cheaper than alternatives, and also reduce other public
costs such as aged care.
Currently, NEATs are available principally through preventive, public health approaches,
targeted only at broad demographic subsectors. Governments advertise their advantages,
and urban planners provide opportunities (36), although these are not always socially
equitable (37). Curative clinical health approaches, customized to individual symptoms
and diagnosed and defined by expert practitioners, are uncommon for NEATs (29, 30).
Even once NEATs become prescribable as treatments, they will also remain important
preventive components of public health. To make NEATs most effective, we need to target
NEATs to individuals most likely to adopt and benefit from them (34).
Introducing prescribable NEATs involves political obstacles and risks. Governments
and health insurers will gain from NEATs, but pharmaceutical corporations may lose.
Political support for NEATs will be higher in countries where pharmaceuticals are
imported, at net public cost. As prescribable NEATs are introduced, legal frameworks
will be needed to avoid certified NEAT providers forming oligopolies to exclude competitors
and control access to sites.
Actionable Recommendations
Our principal long-term recommendation is that we should modify healthcare and health
insurance systems in developed nations, so as to support routine prescription of certified
and insured NEATs for prevention and treatment of the mental health components of
CDS. Our short-term and immediately actionable recommendation is that we should conduct
research as below to design therapies that are effective, cost-effective, accepted,
and adopted.
By using quantitative questionnaire-based approaches, we should test how self-reported
QOL, and use of publicly funded mental health treatments, may be correlated with outdoor
activities and nature exposure at population scale, when adjusted for geographic location
and socioeconomic status; and how self-reported QOL for NEAT participants may differ
from overall population averages.
By using qualitative interview-based approaches, we should investigate how individuals
engaging in NEATs describe effects on their mental and psychological health. These
approaches can be applied for both low-key activities such as visiting parks or beaches
and for high-intensity activities involving powerful emotions, e.g., through wildlife
encounters or risk recreation (38).
By using experimental interventions, we should test what social levers persuade individuals
to increase use of NEATs, for different demographic groups under different social
constraints. This includes preschool and school-age children; university students;
employees at various types of workplaces; families, including those subject to domestic
dysfunction; individuals with disabilities and their carers; and retirees and aged
persons and their carers.
By using controlled experimental approaches, we should differentiate the effects of:
active (38) verses contemplative (39) types of NEAT; time schedules, such as daily
routines, weekends, or intermittent events; places, such as urban greenspace, national
parks, and wilderness areas; and guided verses self-paced NEATs.
Conclusion
We suggest three principal conclusions. First, previous research shows that for at
least some individuals and in at least some circumstances, NEATs can improve mental
health: a basic therapeutic effect is well demonstrated. Second, attempts to deploy
these therapies through public health programs and green prescriptions have not reached
their potential, because we lack the evidence required to advance from demonstration
of therapeutic effect and to design of effective courses of treatment. Therefore,
we identify requirements for research to take this step. Third, once courses of treatment
are ready for use as routinely prescribable therapies, changes to healthcare and health
insurance systems will be needed to support deployment. However, these changes are
relatively minor and are closely analogous to systems already in place for a range
of physiotherapies and psychotherapies.
The research program proposed here is substantial, but to use NEATs in preventing
and treating mental health components of CDSs, it is both necessary and justified
economically. Comparable programs are mandatory for new pharmaceutical treatments.
If NEATs can cut the costs of poor mental health by even 1%, that will be a saving
of billions of dollars annually in most developed nations. This is an investment well
worth making, for both public health research funders and private health insurers.
Author Contributions
All authors listed have made a substantial, direct, and intellectual contribution
to the work and approved it for publication.
Conflict of Interest Statement
The authors declare that the research was conducted in the absence of any commercial
or financial relationships that could be construed as a potential conflict of interest.