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How Might Contact with Nature Promote Human Health? Promising Mechanisms and a Possible Central Pathway

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How might contact with nature promote human health? Myriad studies have linked the two; at this time the task of identifying the mechanisms underlying this link is paramount. This article offers: (1) a compilation of plausible pathways between nature and health; (2) criteria for identifying a possible central pathway; and (3) one promising candidate for a central pathway. The 21 pathways identified here include environmental factors, physiological and psychological states, and behaviors or conditions, each of which has been empirically tied to nature and has implications for specific physical and mental health outcomes. While each is likely to contribute to nature's impacts on health to some degree and under some circumstances, this paper explores the possibility of a central pathway by proposing criteria for identifying such a pathway and illustrating their use. A particular pathway is more likely to be central if it can account for the size of nature's impacts on health, account for nature's specific health outcomes, and subsume other pathways. By these criteria, enhanced immune functioning emerges as one promising candidate for a central pathway between nature and health. There may be others.
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MINI REVIEW
published: 25 August 2015
doi: 10.3389/fpsyg.2015.01093
Edited by:
Marc Glenn Berman,
The University of Chicago, USA
Reviewed by:
Sumitava Mukherjee,
Indian Institute of Management,
Ahmedabad, India
Teresa Helen Horton,
Northwestern University, USA
*Correspondence:
Ming Kuo,
Landscape and Human Health
Laboratory, Department of Natural
Resources and Environmental
Sciences, University of Illinois at
Urbana-Champaign, 1101 West
Peabody Drive, MC-637 Urbana, IL
61801, USA
fekuo@illinois.edu
Specialty section:
This article was submitted to
Cognitive Science,
a section of the journal
Frontiers in Psychology
Received: 04 March 2015
Accepted: 16 July 2015
Published: 25 August 2015
Citation:
Kuo M (2015) How might contact with
nature promote human health?
Promising mechanisms
and a possible central pathway.
Front. Psychol. 6:1093.
doi: 10.3389/fpsyg.2015.01093
How might contact with nature
promote human health? Promising
mechanisms and a possible central
pathway
Ming Kuo
*
Landscape and Human Health Laboratory, Department of Natural Resources and Environmental Sciences, University of
Illinois at Urbana-Champaign, Urbana, IL, USA
How might contact with nature promote human health? Myriad studies have linked the
two; at this time the task of identifying the mechanisms underlying this link is paramount.
This article offers: (1) a compilation of plausible pathways between nature and health;
(2) criteria for identifying a possible central pathway; and (3) one promising candidate
for a central pathway. The 21 pathways identified here include environmental factors,
physiological and psychological states, and behaviors or conditions, each of which has
been empirically tied to nature and has implications for specific physical and mental
health outcomes. While each is likely to contribute to nature’s impacts on health to some
degree and under some circumstances, this paper explores the possibility of a central
pathway by proposing criteria for identifying such a pathway and illustrating their use.
A particular pathway is more likely to be central if it can account for the size of natur e’s
impacts on health, account for nature’s specific health outcomes, and subsume other
pathways. By these criteria, enhanced immune functioning emerges as one promising
candidate for a central pathway between nature and health. There may be others.
Keywords: natural environment, greenspace, immune, mechanism, mental health, literature review
Introduction
Contact with nature has been tied to health in a plenitude of studies. Time spent in and
around tree-lined streets, gardens, parks, and forested and agricultural lands is consistently
linked to objective, long-term health outcomes. The less green a person’s surroundings, the
higher their risk of morbidity and mortality even when controlling for socioeconomic
status and other possible confounding variables. The range of specific health outcomes tied
to nature is startling, including depression and anxiety disorder, diabetes mellitus, attention
deficit/hyperactivity disorder (ADHD), various infectious diseases, cancer, healing from surgery,
obesity, birth outcomes, cardiovascular disease, musculoskeletal complaints, migraines, respiratory
disease, and others, reviewed below. Finally, neighborhood greenness has been consistently tied to
life expectancy and all-cause mortality (see Table 3 in the Supplementary Materials).
These findings raise the possibility that such contact is a major health determinant, and that
greening may constitute a powerful, inexpensive public health intervention. It is also possible,
however, that the consistent correlations between greener surroundings and better health reflect
self-selection healthy people moving to or staying in greener surroundings. Examining the
Frontiers in Psychology | www.fro ntiersin.org 1 August 2015 | Volume 6 | Article 1093
Kuo Nature-health mechanisms
potential pathways by which nature might promote health seems
paramount both to assess the credibility of a cause-and-effect
link and to suggest possible nature-based health interventions.
Toward that end, this article offers: (1) a compilation of plausible
pathways between nature and health; (2) criteria for identifying a
possible central pathway; and (3) one promising candidate for a
central pathway.
How Nature Might Promote Health:
Plausible Pathways
How might contact with nature promote health? To date,
reviews and studies addressing multiple possible mechanisms
(Groenewegen et al., 2006, 2012; Sugiyama et al., 2008;
de Vries et al., 2013; Hartig et al., 2014)havefocused
on four air quality, physical activity, stress, and social
integration. But the burgeoning literature on nature benefits
has revealed an abundance of possible mechanisms: as Figure 1
shows, this review identifies 21 plausible causal pathways
from nature to health. Each has been empirically tied to
contact with nature while accounting for other factors, and
is empirically or theoretically tied to specific health outcomes
(for details on the scope of this review, see Table 1 in the
Supplementary Materials). The 21 pathways identified here
include environmental factors, physiological and psychological
states, and behaviors or conditions, and are summarized below
(for more details on each of these pathways, see Table 2 in the
Supplementary Materials).
Envir onmental Conditions
Some of the plausible pathways from contact with nature
to improved health stem from specific environmental
conditions. Natural environments contain chemical and
biological agents with known health implications. Many
plants give off phytoncides
antimicrobial volatile organic
compounds — which reduce blood pressure, alter autonomic
activity, and boost immune functioning, among other effects
(Komori et al., 1995; Dayawansa et al., 2003; Li et al., 2006,
2009). The air in forested and mountainous areas, and near
moving water, contains high concentrations of negative air ions
(Li et al., 2010), which reduce depression (Terman et al.,
1998; Goel et al., 2005), among other effects (Table 2 in the
Supplementary Materials). These environments also contain
mycobacterium vaccae
, a microorganism that appears to boost
immune functioning (see Lowry et al., 2007 for review).
Similarly, environmental biodiversity
has been proposed to
play a key role in immune function via its effects on the
microorganisms living on skin and in the gut, although the
evidence for this is mixed (Table 2 in the Supplementary
Materials).
The sights
and sounds of nature also have important
physiological impacts. Window views and images of
nature reduce sympathetic nervous activity and increase
parasympathetic activity (e.g., Gladwell et al., 2012; Brown
et al., 2013), restore attention (e.g., Berto, 2005), and promote
healing from surgery (Ulrich, 1984). Sounds of nature played
over headphones increase parasympathetic activation (Alvarsson
et al., 2010). These sympathetic and parasympathetic effects
drive the immune system’s behavior (for review, see Kenney and
Ganta, 2014), with long-term health consequences.
In built environments, trees and landscaping may promote
health not only by contributing positive factors like phytoncides
but also by reducing negative factors. Air pollution
is associated
with myocardial inflammation and respiratory conditions
(Villarreal-Calderon et al., 2012). High temperatures
can
cause heat exhaustion, heat-related aggression and violence,
and respiratory distress due to heat-related smog formation
(Anderson, 2001; Akbari, 2002; Tawatsupa et al., 2012). And
violence
affects physical and mental health (e.g., Groves et al.,
1993). Vegetation filters pollutants from the air (although see
Table 2 in the Supplementary Materials for details), dampens the
urban heat island (e.g., Souch and Souch, 1993), and appears
to reduce violence (Table 2 in the Supplementary Materials for
review).
Physiological and Psychological States
Some of the plausible pathways between contact with nature and
health involve short-term physiological and psychological effects,
which, if experienced regularly, could plausibly account for long-
term health effects.
Blood tests before and after walks in different environments
reveal that levels of health-protective factors increase after
forest but not urban walks. Didehydroepiandrosterone
(DHEA)
increases after a forest walk (Li et al., 2011); DHEA has cardio
protective, anti-obesity, and anti-diabetic properties (Bjørnerem
et al., 2004). Similarly, time in nature increases adiponectin
(Li et al., 2011), which protects against atherosclerosis, among
other things (Table 2 in the Supplementary Materials), and
the immune system
s anti-cancer (so-called Natural Killer, or
NK) cells and related factors (Table 2 in the Supplementary
Materials). NK cells play important protective roles in cancer,
viral infections, pregnancy, and other health outcomes (Orange
and Ballas, 2006).
Further, walks in forested, but not urban areas, reduce
the levels of health risk factors, specifically inflammatory
cytokines (Mao et al., 2012), and elevated blood glucose
(Ohtsuka
et al., 1998). Inflammatory cytokines are released by the
immune system
in response to threat, and have been implicated
in diabetes, cardiovascular disease, and depression (Table 2 in the
Supplementary Materials). Chronically elevated blood glucose
carries multiple health risks, including blindness, nerve damage,
and kidney failure (Sheetz and King, 2002). The powerful effects
of a walk in a forest on blood glucose are particularly striking
(Table 2 in the Supplementary Materials for review).
Contact with nature has a host of other physiological
effects related to relaxation
or stress reduction (Table 2 in the
Supplementary Materials). The experience of nature helps shift
individuals toward a state of deep relaxation and parasympathetic
activity, which improves sleep (El-Sheikh et al., 2013), boosts
immune function in a number of ways (Kang et al., 2011), and
counters the adverse effects of stress on energy metabolism,
insulin secretion, and inflammatory pathways (Bhasin et al.,
2013). Evidence suggests this pathway contributes substantially to
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Kuo Nature-health mechanisms
FIGURE 1 | The nature-health link: filling in the details. This Figure
summarizes the state of the scientific literature on nature and health, listing (1)
the active ingredients” in nature that have been identified as having impacts on
health or health antecedents; (2) physiological/psychological states, behaviors,
and conditions tied to both nature and health; and (3) specific health outcomes
that have been tied to nature (controlling for socioeconomic variables). Note that
physical activity (in brackets) is only sometimes tied to nature; and that allergies,
asthma, and eczema are sometimes positively and sometimes negatively tied to
nature. DHEA: didehydroepiandrosterone; acute UTI: acute urinary tract
infection; ADHD: attention deficit hyperactivity disorder; IDIC: infectious disease
of the intestinal canal; MUPS: medically unexplained physical symptoms; URTI:
upper respiratory tract infection.
the link between nature and health (Table 2 in the Supplementary
Materials).
Three psychological effects of nature experiences of awe
(Shiota et al., 2007), enhanced vitality (Ryan et al., 2010), and
attention restoration (Table 2 in the Supplementary Materials)
offer additional possible pathways between nature and health.
Regular experiences of awe are tied to healthier, lower levels of
inflammatory cytokines (Stellar et al., 2015); the ties between
nature and awe, and awe and cytokines, respectively, may help
explain the effects of forest walks on cytokines above. Similarly,
feelings of vitality predict resistance to infection (Cohen et al.,
2006) and lowered risk of mortality (Penninx et al., 2000).
Attention restoration could theoretically reduce accidents caused
by mental fatigue and, by bolstering impulse control, reduce risky
health behaviors such as smoking, overeating, and drug or alcohol
abuse (Wagner and Heatherton, 2010).
Behaviors and Conditions
The remaining four possible pathways between contact with
nature and health identified here involve behaviors and
conditions: physical activity
,obesity, sleep,andsocialties.
Physical activity is a major contributor to health (Centers for
Disease Control and Prevention [CDC], 2015), and intuitively
we associate green space with physical activity but empirically
this relationship is surprisingly inconsistent (Table 2 in the
Supplementary Materials) and may hold only under certain
conditions and for certain populations. Perhaps still more
surprising, while greener residential areas do not consistently
predict physical activity, they do consistently predict lower
rates of obesity (for review, see Table 2 in the Supplementary
Materials); this suggests the pathway between nature and obesity
may depend less on natures effects on physical activity and more
on its effects on adiponectin, stress, and impulse control. Both
sleep and social ties are major contributors to health (Table 2 in
the Supplementary Materials); contact with nature contributes to
both better sleep (Morita et al., 2011; Astell-Burt et al., 2013)and
stronger social ties (see Table 2 in the Supplementary Materials
for review).
Exploring the Possibility of a Central
Pathway
Each of the mechanisms above is likely to contribute to natures
impacts on health to some degree and under some circumstances.
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Kuo Nature-health mechanisms
Most likely, some pathways will play a larger role than others.
This paper explores the possibility that one or a few pathways
may explain the lion’s share of the link between nature and
health by proposing criteria for identifying central pathways and
illustrating the application of these criteria.
First, a pathway is more likely to be central if it can account
for the size of natures impacts on health. A study of over 345,000
people living in greener and less green residential surroundings
revealed large differences in the prevalence of disease; even
after controlling for socioeconomic status, prevalence for 11
major categories of disease was at least 20% higher among the
individuals living in less green surroundings (Maas et al., 2009).
For a single pathway to plausibly account for the bulk of the tie
between nature and health, the mechanism involved would need
to have substantial effects on health, and be substantially affected
by contact with nature.
Second, a pathway is more likely to be central if it can
account for specific health outcomes tied to nature. Although
health is often treated as a unitary construct in the nature-health
literature, poor health takes a multiplicity of separable, largely
independent forms. A pathway that leads to one health outcome
may not lead to others; for example, reduced air pollution may
lessen respiratory symptoms, but is not likely to affect ADHD
symptoms. A central pathway between nature and health should
accountformany,ifnotmost,ofthespecichealthoutcomestied
to nature.
Third, a pathway is more likely to be central if it subsumes
other pathways. To the extent that multiple nature-health
pathways feed into a particular pathway between nature and
health, that pathway is more central to the relationship between
nature and health.
These three criteria can be applied to any given pathway to
determine its centrality. In this paper, they are applied to one
particular pathway: enhanced immune functioning.
Criterion #1: Accounting for the Size of the
Nature-Health Link
Determining whether a particular pathway can account for the
size of the nature–health link requires examining the effect sizes
for the nature–mechanism and mechanism–health relationships.
For the immune system, the existing literature reveals both these
effect sizes to be large.
Time spent in nature has substantial beneficial effects on
the immune system, raising positive indicators, and lowering
negative ones. Two 2-h forest walks on consecutive days
increased the number and activity of anti-cancer NK cells by 50
and 56%, respectively, and activity remained significantly boosted
even a month after returning to urban life 23% higher than
before the walks (Li, 2010). Moreover, extended time in a forest
decreased inflammatory cytokines implicated in chronic disease
by roughly one-half (Mao et al., 2012). Urban walks have no such
effect.
The immune system, in turn, has powerful effects on health.
The cytotoxic activity of NK cells is important in preventing
cancer in an 11-year study, the incidence of cancer among the
individuals in the middle and top third of cytotoxic activity was
roughly 40% less than that among individuals with low levels
of NK activity (Imai et al., 2000). NK cells also play important
health-promoting roles in fighting viral and other infections, in
autoimmune disorders, and in pregnancy (see Orange and Ballas,
2006 for review). Moreover, inflammatory cytokines are thought
to play an important role in a host of chronic diseases, including
diabetes, cardiovascular disease, and depression (Cesari et al.,
2003; Wellen and Hotamisligil, 2005; Dowlati et al., 2010).
It appears that enhanced immune function fulfills the first
criterion for a central pathway: it can account for the size of
natures apparent impacts on health.
Criterion #2: Accounting for the Specific
Health Outcomes Tied to Nature
Each specific health outcome tied to nature constitutes a testable
hypothesis for any proposed central pathway; the more specific
health outcomes a pathway can account for, the more central its
role.
Contact with nature has been linked to a plethora of
specific health outcomes; in general, the more contact with
nature, the better the health outcome, even after controlling
for socioeconomic status and other factors. For each of the
following, available evidence points to a favorable impact: acute
urinary tract infections, anxiety disorder, ADHD, birth outcomes,
cancer, cardiovascular disease, depression, diabetes mellitus,
healing from surgery, infectious disease of the intestinal canal,
musculoskeletal complaints, medically unexplained physical
symptoms (MUPS), migraines, upper respiratory tract infections,
respiratory disease, and vertigo (for details, see Table 3 in the
Supplemental Materials). For allergies, asthma, and eczema, the
apparent impact of nature varies; depending on the specific
measures used and the place, the relationships are positive,
negative, or null (Table 3 in the Supplemental Materials).
To determine whether enhanced immune functioning could
account for these specific health outcomes, the literature on
immune functioning and each of the 18 specific outcomes
was collected and reviewed. Available evidence indicates that
enhanced immune functioning may be able to account, wholly
or partially, for all 18 (see Figure 2).
Oneofthechieffunctionsoftheimmunesystemisto
ward off infectious disease, protecting the body from bacterial,
parasitic, fungal, and viral infections (National Institutes of
Health [NIH], 2012). Thus enhanced immune function could
clearlyexplainwhycontactwithnature is tied to lower rates of
acute urinary tract infections, infectious disease of the intestinal
canal, and upper respiratory tract infections. Further, for health
outcomes with multiple possible origins, enhanced immune
function can account for cases with infectious origins — for
example, infectious forms of respiratory disease but perhaps
not forms of respiratory disease with non-infectious origins.
Similarly, enhanced immune function can account for MUPS and
vertigo with infectious origins (Bovo et al., 2006; Deary et al.,
2007, respectively).
Two other key roles of the immune system are to assist
in wound healing, and to seek out and destroy tumor cells.
Thus enhanced immune function can account for the effect of a
hospital view of nature on recovery from surgery (Ulrich, 1984),
as well as the relationship between residential greenness and
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Kuo Nature-health mechanisms
FIGURE 2 | Enhanced immune function as one possible central
pathway. All items in white text are currently known or have been
proposed to be causally tied to immune function. As the Figure
shows, enhanced immune function can account, at least partially, for
each of the specific health outcomes currently tied to nature and
may subsume, at least partially, all but two of the other pathways.
Other pathways may also contribute the nature-health link, and other
central pathways may exist.
lower rates of cancer (Li et al., 2010). Further, the immune system
governs inflammation, which is involved in allergies (National
Institutes of Health [NIH], 2015), anxiety disorder (Salim et al.,
2012), asthma (Murdoch and Lloyd, 2010), cardiovascular disease
(Mari et al., 2002; Ho et al., 2010; Schiffrin, 2013), depression
(Calabrese et al., 2014), diabetes mellitus (Pedicino et al.,
2013), eczema (National Institutes of Health [NIH], 2014), and
musculoskeletal complaints (Ji et al., 2002; Wang et al., 2011).
Finally, immune functioning is important in healthy birth weight
(Moffett et al., 2014), and is suspected to play a role in ADHD
(Segman et al., 2002; Budziszewska et al., 2010) and migraines
(Bruno et al., 2007).
Available evidence indicates that enhanced immune function
fulfills the second criterion for a central pathway.
Criterion #3: Subsuming Other Pathways
between Nature and Health
A nature–health pathway is more central if it subsumes other
pathways; the more other pathways it subsumes, the more central
its role. As Figure 2 shows, the current literature suggests
enhanced immune function can subsume as many as 18 out of
the 20 other possible pathways between nature and health.
Enhanced immune function is known to wholly or partially
subsume 11 other pathways. Each of the following is known
to enhance immune function adiponectin (Fantuzzi, 2013),
reduced air pollution (e.g., Nadeau et al., 2010), awe (Stellar
et al., 2015), normalized levels of blood glucose (as compared
to elevated levels, Geerlings and Hoepelman, 1999), reduced
obesity (de Heredia et al., 2012), physical activity (Shepherd
et al., 1991), phytoncides (Li et al., 2009), better sleep
(Besedovsky et al., 2012), social ties (Kiecolt-Glaser et al.,
2002; Robles and Kiecolt-Glaser, 2003), relaxation and stress
reduction (Abboud et al., 2012; Bhasin et al., 2013), and
reduced immediate and long-term traumatic stress due to
violence (e.g., Baum et al., 1993). Note that these pathways
may be partially or wholly subsumed by the enhanced immune
functioning pathway between nature and health; if a pathway
contributes to health via both the immune system and other
effects, it is partially subsumed by the immune function
pathway.
For seven additional pathways, while there is no direct
evidence tying them to human immune function, there is
indirect evidence suggesting such a tie. DHEA (Hazeldine
et al., 2010), mycobacterium vaccae (Lowry et al., 2007), and
negative air ions (Yamada et al., 2006)areallknownto
improve immune function in mice. Vitality enhances resistance
to upper respiratory tract infections (see vigor findings in Cohen
et al., 2006), an effect mostly likely mediated via enhanced
immune functioning. Both visual (e.g., Brown et al., 2013)and
auditory (e.g., Alvarsson et al., 2010) nature stimuli are likely to
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Kuo Nature-health mechanisms
boost immune function by way of their demonstrated effects
on parasympathetic activity, and the subsequent effects of
parasympathetic activity on immune function (Kenney and
Ganta, 2014). And environmental biodiversity has been proposed
to help train and regulate the immune system, although the
findings here are correlational and mixed (e.g., Ruokolainen et al.,
2014).
Enhanced immune function fulfills the third criterion for a
central pathway.
Conclusion
This review reveals a multiplicity of mechanisms by which
contact with nature might promote health, as well as a promising
candidate for a central pathway. There may be other mechanisms,
such as other physiological effects, reduced accidents, and
healthier behaviors. There may also be other central contributors
to the nature-health link of those reviewed here, deep
relaxation, attention restoration and impulse control, sleep, and
social ties seem particularly worthy of attention. No doubt some
of the plausible pathways identified here will prove either not
to contribute substantially to natures impact on health, or to
contribute only under certain limited circumstances; here, the
roles of improved air quality, environmental biodiversity and
microbiota, and physical activity merit closer study.
These limitations notwithstanding, this review makes a
number of contributions to our understanding of nature and
health, to future investigation in this area, and to the creation
of healthy human habitats. The multiplicity of nature–health
pathways identified here lends credibility to the hypothesis that
nature actually promotes health, aswellasapotentialexplanation
for the startling size and scope of natures apparent impact.
With so many contributing pathways operating in concert, the
cumulative effect could be quite large even if many of the
individual pathways contribute only a small effect that is, the
effect of exposure to phytoncides plus exposure to mycobacteria
vaccae plus increased adiponectin plus stronger social ties plus
better sleep, etc., could indeed be quite large, and if some of the
pathways, such as enhanced immune function, contribute a large
effect, the combined effect would be larger still.
For future work in this area, the criteria here give researchers
interested in central mechanisms a means of using existing
literature to assess the centrality of a particular mechanism. In
addition the detailed reviews provided in the Supplementary
Materials may provide a useful starting point for researchers
interested in specific pathways or specific health outcomes of
nature.
Finally, the findings here can help guide the creation of
healthy human habitats. The existing literature speaks to the
value not only of “wild” nature but also everyday” nature
the views and green spaces where we live. That physical activity
is not consistently related to greener environments suggests
that our conceptualization of health-promoting greenspaces
should center at least as much on oases as on ball fields,
and on greenspaces for walking and quiet contemplation as
much as on recreation areas. The findings here suggest that
such oases should incorporate plants — especially trees, soil,
and water (preferably moving) and should be designed to
induce feelings of deep relaxation, awe, and vitality. Providing
these green oases, especially in areas where health risks are
high and landscaping is sparse, might be an inexpensive,
powerful public health intervention and address persisting health
inequalities.
Acknowledgments
I am grateful to the TKF Foundation for encouragement and
financial assistance in gathering some of the necessary literature
for this work through its Nature Sacred National Awards
program. This review is more clear, better structured, more
interesting, and more complete than it would have been without
the thoughtful intervention of Kirstin Wilcox, Rafter S. Ferguson,
Dexter Locke, Meghan Frankel, Natalia Maurer, and reviewers
Sumitava Mukherjee and Teresa Helen Horton: thank you!
Supplementary Material
The Supplementary Material for this article can be found
online at: http://journal.frontiersin.org/article/10.3389/fpsyg.
2015.01093
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Conflict of Interest Statement: The author declares that the research was
conducted in the absence of any commercial or financial relationships that could
be construed as a potential conflict of interest.
Copyright © 2015 Kuo. This is an open-access article distributed under the terms
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Frontiers in Psychology | www.frontiersin.org 8 August 2015 | Volume 6 | Article 1093
... Risk perceptions suggest perceived urgency to address climate change solutions. In contrast to impressions of other people's beliefs and perceptions 40 (Leviston et al., 2013;Mildenberger & Tingley, 2017), most believe that climate change is occurring, serious and human-caused (Akerlof et al., 2010;Capstick et al., 2015;Fagan & Huang, 2020;Krosnick & MacInnis, 2020). However, survey data also reveal some problematic nature of perceptions. ...
... For some, addressing climate change will be seen as antithetical to boosting the economy . Increasing uncertainty of diametrically opposed climate change beliefs (Krosnick & MacInnis, 2020) and ideologically aligned disagreement about what responses should be taken (Funk, 2021) are indicators of polarization of opinions about climate change and solutions. ...
... These filters result in predictable correlates of these beliefs. The strongest correlates are people's political affiliations and ideology: Left-leaning individuals believe more strongly in human-caused climate change and report greater willingness to support solutions (Hornsey et al., 2016;Krosnick & MacInnis, 2020). Weaker, though still notable correlates, reveal that younger people, women, those with higher income and education, and racial minorities are more likely to endorse such beliefs (Hornsey et al., 2016). ...
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Understanding the role of psychological science in shaping human behaviour towards promoting and maintaining a healthy environment is critical to a safe, sustainable, and balanced ecosystem in Africa. In addition to addressing the negative impact of climate change on physical and mental health, psychologists can help build resilience to mitigate the effects of climate change. Against the backdrop of COVID-19, the Nigerian Psychological Association has pursued environmental advocacy including focusing its 2021 national conference on ‘’global climate change, ecosystem and behaviour: issues and action plans.” In addition, a number of psychology departments in Nigeria have hosted pro-environment programmes. Similarly, the Ghana Psychological Association has collaborated with corporate and religious bodies to educate the public on climate change initiatives and has called for an annual week-long celebration to promote climate change initiatives. And additionally, in East Africa, before the onset of the COVID-19 pandemic, the Uganda Council of Psychologists began working hand-in-hand with local universities to create climate change awareness campaigns, planning to organise field trips and conduct survey studies in the most impacted regions of the country. Ultimately, this calls for behavioural and societal change to avert future disasters. As scientist-practitioners, we need to adopt a multi-sectoral approach and tailored research to address climate change concerns in Africa.
... Sources: a. Li 2010; Song et al. 2016;b. Hartig et al. 2014; c. see Li et al. 2008;Kuo 2015;d. Li 2010;Kuo 2015;e. ...
... Hartig et al. 2014; c. see Li et al. 2008;Kuo 2015;d. Li 2010;Kuo 2015;e. Hansen et al. 2017;Oh et al. 2017;f. ...
... ▪ Reduced risk of noncommunicable diseases, including cardiovascular disease (Nieuwenhuijsen 2018;Wolf et al. 2020) and type II diabetes mellitus (den Braver et al. 2018;Twohig-Bennett and Jones 2018) ▪ Reduced indicators for stress and disease, such as salivary stress hormones, heart rate, and blood pressure (Meyer and Bürger-Arnd 2014;Hansen et al. 2017;Twohig-Bennett and Jones 2018;Wolf et al. 2020); forest bathing, in particular, seems to have positive effects on physiological states and immune activity (Case Study 1) ▪ Lower body mass index (Lachowycz and Jones 2011;Wolf et al. 2020), a predictor of other health outcomes ▪ Improved pregnancy and birth outcomes Braubach et al. 2017;Nesbitt et al. 2017;Twohig-Bennett and Jones 2018;Kloog 2019) ▪ Reduced risk of premature death; most evidence supports a significant inverse relationship between premature mortality and residential greenness (Gascon et al. 2016;Twohig-Bennett and Jones 2018;Rojas-Rueda et al. 2019) Exposure to forests and nature can improve people's immune systems (Kuo 2015;Shanahan et al. 2015;Braubach et al. 2017). Being exposed to a diverse array of microorganismsto which humans were exposed for much of our evolutionary history-may stimulate the immune system and enhance its ability to distinguish between beneficial and harmful bacteria, which can improve health outcomes, including autoimmune disorders, allergies, depression, or cancer (Rook 2013;Kuo 2015;Sandifer et al. 2015;von Hertzen et al. 2015;Lai et al. 2019). ...
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Better Forests, Better Cities evaluates how forests both inside and outside city boundaries benefit cities and their residents, and what actions cities can take to conserve, restore and sustainably manage those forests. This report is the first of its kind comprehensive resource on the connection between cities and forests, synthesizing hundreds of research papers and reports to show how all forest types can deliver a diverse suite of benefits to cities.
... Risk perceptions suggest perceived urgency to address climate change solutions. In contrast to impressions of other people's beliefs and perceptions 40 (Leviston et al., 2013;Mildenberger & Tingley, 2017), most believe that climate change is occurring, serious and human-caused (Akerlof et al., 2010;Capstick et al., 2015;Fagan & Huang, 2020;Krosnick & MacInnis, 2020). However, survey data also reveal some problematic nature of perceptions. ...
... For some, addressing climate change will be seen as antithetical to boosting the economy . Increasing uncertainty of diametrically opposed climate change beliefs (Krosnick & MacInnis, 2020) and ideologically aligned disagreement about what responses should be taken (Funk, 2021) are indicators of polarization of opinions about climate change and solutions. ...
... These filters result in predictable correlates of these beliefs. The strongest correlates are people's political affiliations and ideology: Left-leaning individuals believe more strongly in human-caused climate change and report greater willingness to support solutions (Hornsey et al., 2016;Krosnick & MacInnis, 2020). Weaker, though still notable correlates, reveal that younger people, women, those with higher income and education, and racial minorities are more likely to endorse such beliefs (Hornsey et al., 2016). ...
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The New Zealand Psychological Society, publisher of the Global Psychology Alliance Ebook 'Climate Action and Global Psychology', has opened access to the publication ahead of COP27, to allow for greater promotion and awareness of this important contribution to the field of climate psychology. The book can now be downloaded free of charge from the Society's website here: https://lnkd.in/gNHT2S2h This is the PDF version that members of the profession and public can download as they wish. If people want the published E-book version, they can contact the Society's professional development officer whose email address is on the webpage and a copy will be sent to them. We hope this contribution to the literature will be publicised widely across the professions and to those involved in climate action, policy development, teaching, research and professional practice. Closer to COP27, we will be producing advertising material describing the book's contents in more detail. In the interim, this quote from the Editors' Preface provides an outline of the book: "Climate Action and Global Psychology offers a unique, multi-national perspective on organised psychology’s nascent collaborative efforts to address the world’s climate crisis. This volume is a combination of theoretical and empirical work, varying according to section and topic. Leadership models related to major global crises like climate tend to be more theoretical, while chapters on projects in specific countries are more empirically oriented. The efforts of global psychology and its constituent professional organisations must address the need to understand the imminent threats posed for Indigenous peoples by climate change and seek ways to ensure psychology empowers and supports the actions of their people." We encourage groups to promote the Ebook to their members through their own communication networks. Ngā mihi Brian Brian Dixon Co-convenor, Climate Psychology Task Force Executive member for Te Taiao/Environment NZ Psychological Society
... The significant interest in forest recreation observed over the years [3,5,6] can be explained, on the one hand, by the universality and accessibility of forests, and, on the other hand, by their beneficial effects on the health of their visitors. Forests have a positive effect on mental health [7][8][9]. Spending time in a forest has positive effects on concentration and performance [10], stress reduction [11,12], and can even aid in the treatment of depression [13,14]. Recent studies show that snowy forests can also have a positive impact on the mental state of their visitors [15,16]. ...
Article
Full-text available
Studies show that forests are one of the main recreational destinations. This can be explained by their beneficial effects on the health of their visitors, which can be attributed to compounds from the terpene group. The aim of this research was to determine the chemical composition of air in the interiors of Nemoral Scots pine forests and submountainous beech forests, with the determination of compounds of the terpene group. Samples of organic compounds present in the air were collected with the use of Tenax TA sorbent tubes. The process of separation, identification, and determination of the extracted organic compounds was carried out with the use of the gas chromatography technique integrated with a flame ionization detector. Additional identification of the extracted compounds was carried out with the use of GC coupled with mass spectrometry. The most abundant group of compounds was the aliphatic hydrocarbons, both saturated (linear and branched) and unsaturated (terpenes). Carbonyl compounds were also found in the collected samples, but they constituted no more than 10% of all compounds present on the chromatograms. The concentrations of terpenes and terpenoids in the forest atmosphere varied from 10 to 74 µg·m−3 , representing on average 33% of the total volatile organic compounds.
... Scientists have then investigated its benefits on physical, mental, emotional, and social health outcomes [134]. Forest bathing is known to boost immunity [113,130,135], a plausible central pathway between nature exposure and human health benefits [136]. ...
Article
Full-text available
Significance Globally, cardiovascular disease (CVD) and cancer are leading causes of morbidity and mortality. While having different etiologies, CVD and cancer are linked by multiple shared risk factors, the presence of which exacerbate adverse outcomes for individuals with either disease. For both pathologies, factors such as poverty, lack of physical activity (PA), poor dietary intake, and climate change increase risk of adverse outcomes. Prior research has shown that greenspaces and other nature-based interventions (NBIs) contribute to improved health outcomes and climate change resilience. Objective To summarize evidence on the impact of greenspaces or NBIs on cardiovascular health and/or cancer-related outcomes and identify knowledge gaps to inform future research. Methods Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 and Peer Review of Electronic Search Strategies (PRESS) guidelines, we searched five databases: Web of Science, Scopus, Medline, PsycINFO and GreenFile. Two blinded reviewers used Rayyan AI and a predefined criteria for article inclusion and exclusion. The risk of bias was assessed using a modified version of the Newcastle–Ottawa Scale (NOS). This review is registered with PROSPERO, ID # CRD42021231619. Results & discussion Of 2565 articles retrieved, 31 articles met the inclusion criteria, and overall had a low risk of bias. 26 articles studied cardiovascular related outcomes and 5 studied cancer-related outcomes. Interventions were coded into 4 categories: forest bathing, green exercise, gardening, and nature viewing. Outcomes included blood pressure (BP), cancer-related quality of life (QoL) and (more infrequently) biomarkers of CVD risk. Descriptions of findings are presented as well as visual presentations of trends across the findings using RAW graphs. Overall studies included have a low risk of bias; and alluvial chart trends indicated that NBIs may have beneficial effects on CVD and cancer-related outcomes. Conclusions & implications (1) Clinical implication : Healthcare providers should consider the promotion of nature-based programs to improve health outcomes. (2) Policy implication : There is a need for investment in equitable greenspaces to improve health outcomes and build climate resilient neighborhoods. (3) Research or academic implication : Research partnerships with community-based organizations for a comprehensive study of benefits associated with NBIs should be encouraged to reduce health disparities and ensure intergenerational health equity. There is a need for investigation of the mechanisms by which NBIs impact CVD and exploration of the role of CVD biological markers of inflammation among cancer survivors.
... For example, IVEs has been applied to study the effects of nature on stress reduction (Anderson et al., 2017;Xiaobo et al., 2019), emotional improvement (Yu et al., 2018), and cognitive performance (Mostajeran et al., 2021) in recent. The use of IVEs in investigating the restorative effects of nature has been validated by comparing with studies using pictures (Mostajeran et al., 2021) and field sites (Browning et al., 2020).We intended to investigate short-term exposure to natural environments as aware that the mechanistic pathways of nature's benefits on psychological functioning are manifold and systematic across temporal and spatial scales (Kuo, 2015). Short-term exposure has important public health significance, especially for populations with limited access to nature due to physical constraints or busy work schedules (Browning et al., 2020). ...
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Short-term exposure to nature has excellent potential to be used as a public health intervention measure. Nevertheless, the physiological and psychological mechanisms of this health benefit are still unclear. In this study, we intend to verify the effects of short-term exposure to nature on psychological functioning and to explore the underlying mechanism through experiments conducted in immersive virtual environments (IVEs). Participants were randomly exposed to videos of an urban forest and an indoor environment in IVEs. Before and after the exposure, a participant's self-perceived stress and cognitive performance were measured using the PSS-14 form and the Stroop task, respectively. Their brain activities during the exposure were measured using the electroencephalogram (EEG). The PSS-14 and the Stroop task results confirmed the benefits of stress reduction and cognitive performance improvements from short-term nature exposure. At the same time, rhythmic brain activities during nature exposure indicated better attentional states. The electrodes around the parietal region detected significantly stronger power spectral density of the theta band than other bands. Also, participants showed high functional connectivity among different brain parts during nature exposure, which revealed better cognitive flexibility. The topographic pattern of the differences in functional connectivity overlapped well with the default mode network (DMN)-a "task-negative" network active during the resting state. The overlap indicated a lower cognitive processing load when exposing to nature. Our results support the hypothesis that nature's restorative effects mainly come from effortless processing in natural environments.
... In an attempt to organise empirical evidence from different disciplines, previous reviews predominantly have focused on four general pathways; (1) air quality, (2) physical activity, (3) stress and (4) social contact (De Vries et al. 2013). Yet, in a comprehensive review of pathways Kuo (2015) identified up to 21 plausible pathways from nature to health (both physical and mental). Subsequently, the use of the four pathways may not be suitable for the topic of urban greenspace and health. ...
Thesis
To improve causality, this thesis used the counterfactual framework to develop two novel and statistically robust approaches to analyse the effect of urban greenspace on mental health. The first approach was a cross-sectional assessment that used statistical matching in addition to regression modelling to establish the effect of local public greenspace on a person’s mental health for those with and without a private garden. The second approach used longitudinal data in a Before-After Control Intervention study design to establish the effect of the change in different greenspace characteristics on mental health when a person moved between urban areas. Both these approaches were applied to the British Household Panel Survey – a nationally representative survey of Great Britain containing individual-level information on mental health and the socio-economic confounders of mental health. Findings from the first approach suggested that the effect of access to private greenspace on mental health outweighs the beneficial effects of access to public greenspace. Specifically, having a private domestic garden substantially reduced the maximum probability of poor mental health for men and women, regardless of their access to local public greenspace. The second approach highlighted the importance of greenspace quality and proximity for mental health. Bird species richness and distance to nearest greenspace, proxy measures for greenspace quality and proximity respectively, provided the most inference when modelling the effect of change in greenspace characteristics on mental health. Comparatively, measures of greenspace quantity and recognised standards and guidelines of greenspace access provided less inference than a model that did not include a measure of greenspace. Given these results, greenspace quality, proximity and access to private gardens should be a priority for future policies to improve the status of both urban greenspace and mental health in Great Britain.
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The special issue presents international experiences with COVID-19 in the years 2020 and 2021 on outdoor recreation and nature-based tourism. To set the scene, a bibliometric and qualitative analysis illustrates and clusters recent publications on COVID-19. Against this background contributions from Japan, China, Brazil, the United States, New Zealand, Taiwan, Australia, Sweden, Poland and Ireland draw a truly international picture of the pandemic crisis, the effects, coping behavior and related strategies. The papers contribute to the COVID-19 related research by documenting the shock in the field of outdoor recreation and tourism, by understanding the immediate consequences on behavior and the required managerial consequences and finally, by analyzing the possible follow up effects including long term effects, discussing resilient solutions and proposing new strategies. In the discussion section we try to answer the questions whether the high visitation rate in recreation facilities, forests, parks and protected areas will remain, and whether adapted visitor management concepts will be required. In addition, we discuss possible implications for urban planning and management. Finally, based on a changing connectedness to nature also possible positive effects by the pandemic are discussed which may lead to a new target group in outdoor recreation and nature-based tourism.
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Nature-based tourism may provide a well-structured format to facilitate opportunities for wellness. This research collected in-depth data from 72 tourists to explore the holistic wellbeing outcomes of experiences at the Mt. Barney Lodge in Queensland, Australia. We found that the Lodge offers a multitude of benefits across wellbeing dimensions. Such research indicates that nature is a public health resource, and that nature-tourism enterprises have the potential to deliver nature therapies. Creating carefully planned packages that deliver both nature contact and connectedness, offer self-development and transformative impacts and are partnered with mechanisms to encourage consistent nature contact, may be integral to the lasting wellbeing of people and planet.
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Background Evidence on associations of residential greenness with dyslipidemia is limited, particularly regarding dose-response relations and mediation. Objectives To investigate associations between greenness and dyslipidemia, non-linear dose-response relationships and mediators. Methods This cross-sectional study draws on the 2018 Fujian Behavior and Disease Surveillance (FBDS) cohort that used multi-stage stratified random sampling from the general population of Fujian Province, China. Participants with one or more abnormities in total cholesterol (TC), triglycerides (TG), high-density lipoprotein cholesterol (HDL-C), or low-density lipoprotein cholesterol (LDL-C) were classified as having dyslipidemia. Residential greenness was operationalized as 3-year average of the normalized difference vegetation index (NDVI500m) and enhanced vegetation index (EVI500m). A doubly robust approach was used for effect quantification. Dose-response relations were studied with natural cubic splines. Mediation via physical activity (PA), body mass index (BMI), PM2.5, PM10, SO2, and NO2 was also examined. Results Data from 43,183 participants were analyzed. Increases in NDVI500m and EVI500m residential greenness were associated with decreased dyslipidemia risk and improved blood lipids. Non-linear dose response relationships were discovered. Significant reduction of dyslipidemia risk was observed at levels of EVI500m > 0.48 and NDVI500m > 0.65. Joint mediation effects of PA, BMI, PM2.5, PM10, NO2, and SO2 on the associations of NDVI500m and EVI500m with dyslipidemia risk were 49.74% and 44.64%, respectively. Conclusions Increased residential exposure to greenness was associated with decreased risk of dyslipidemia. A non-linear dose-response relationship between greenness and dyslipidemia suggests that specific thresholds of greenness need to be reached in order to achieve effects. BMI, PM2.5, and PM10 partially mediated the association.
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Human birthweight is subject to stabilizing selection. Large babies are at risk of obstetric complications such as obstructed labour, which endangers both mother and child. Small babies are also at risk with reduced survival. Fetal growth requires remodelling of maternal spiral arteries to provide an adequate maternal blood supply to the placenta. This arterial transformation is achieved by placental trophoblast cells, which invade into the uterine wall. Under-invasion is associated with fetal growth restriction; but if invasion is excessive large babies can result. A growing body of evidence suggests that this process is controlled by interactions between killer-cell immunoglobulin-like receptors (KIRs) expressed on maternal uterine natural killer cells (uNK) and their corresponding human leukocyte antigen-C (HLA-C) ligands on invading trophoblast. Mothers with the KIR AA genotype and a fetus with a paternal HLA-C2 allele tend to have small babies, because this combination inhibits cytokine secretion by uNK. Mothers with the activating KIR2DS1 gene and an HLA-C2 fetus are more likely to have large babies. When KIR2DS1 binds to HLA-C2 this increases secretion of cytokines that enhance trophoblast invasion. We conclude that specific combinations of the highly polymorphic gene systems, KIR and HLA-C, contribute to successful reproduction by maintaining birthweight between two extremes. © 2015 The Author(s) Published by the Royal Society. All rights reserved.
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Cytokines are key regulatory mediators involved in the host response to immunological challenges, but also play a critical role in the communication between the immune and the central nervous system. For this, their expression in both systems is under a tight regulatory control. However, pathological conditions may lead to an overproduction of pro-inflammatory cytokines that may have a detrimental impact on central nervous system. In particular, they may damage neuronal structure and function leading to deficits of neuroplasticity, the ability of nervous system to perceive, respond and adapt to external or internal stimuli. In search of the mechanisms by which pro-inflammatory cytokines may affect this crucial brain capability, we will discuss one of the most interesting hypotheses: the involvement of the neurotrophin brain-derived neurotrophic factor (BDNF), which represents one of the major mediators of neuroplasticity.
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Background Western lifestyle is associated with high prevalence of allergy, asthma and other chronic inflammatory disorders. To explain this association we tested the ‘biodiversity hypothesis’, which posits that reduced contact of children with environmental biodiversity, including environmental microbiota in natural habitats, has adverse consequences on the assembly of human commensal microbiota and its contribution to immune tolerance.Methods We analysed four study cohorts from Finland and Estonia (n = 1044) comprising children and adolescents aged 0.5–20 yrs. The prevalence of atopic sensitization was assessed by measuring serum IgE specific to inhalant allergens. We calculated the proportion of five land-use types—forest, agricultural land, built areas, wetlands, and water bodies—in the landscape around the homes using the CORINE2006 classification.ResultsThe cover of forest and agricultural land within 2–5 km from the home was inversely and significantly associated with atopic sensitization. This relationship was observed for children 6 years of age and older. Land-use pattern explained 20% of the variation in the relative abundance of Proteobacteria on the skin of healthy individuals, supporting the hypothesis of a strong environmental effect on the commensal microbiota.Conclusions The amount of green environment (forest and agricultural land) around home was inversely associated with the risk of atopic sensitization in children. The results indicate that early life exposure to green environments is especially important. The environmental effect may be mediated via the effect of environmental microbiota on the commensal microbiota influencing immunotolerance.This article is protected by copyright. All rights reserved.
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Attention deficit hyperactivity disorder (ADHD) is a common neurodevelopmental disorder, where family data support substantial heritability. To date, association studies focussed mainly on genes regulating dopaminergic neurotransmission. Interleukin-1 (IL-1) activity in the brain has been implicated with differentiation of dopaminergic neurons and modulation of central monoaminergic reactivity. We investigated the role of interleukin-1 receptor antagonist (IL-1Ra) gene variable number tandem repeat (VNTR) polymorphism, in a sample of 86 children with DSM-IV ADHD and their parents. Transmission disequilibrium analysis showed increased transmission of the IL-1Ra 4-repeat allele (χ² = 4.07, P = 0.04) and decreased transmission of the 2-repeat allele (χ² = 4.59, P = 0.03) to affected children. The 4-repeat allele was associated with a significantly increased risk for ADHD (χ² = 4.46, df 1, P= 0.035, RR = 1.292, 95% CI 1.01-1.66). The IL-1Ra 2-repeat allele was associated with a significantly decreased risk for ADHD (χ² = 4.65, df 1, P = 0.03, RR = 0.763, 95% CI 0.59-0.98). If replicated, this finding may point to a role for brain cytokine activity in the etiopathogenesis of ADHD.
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Natural killer (NK) cells are lymphocytes of the innate immune system that are critical in host defense and immune regulation. They are activated or inhibited through the ligation of germline-encoded receptors and are involved in mediating cytotoxicity, in producing cytokines and in providing co-stimulation to cells of the adaptive immune system. NK cells play important roles in viral infections, autoimmunity, pregnancy, cancer and bone marrow transplantation. This review highlights recent developments in the understanding of the role of human NK cells in health and disease. Published by Elsevier Inc.
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THE CRISIS of violence in the United States has expanded to include more than the traditional emphasis on the victim and perpetrator. We would like to bring attention to a previously underrecognized group of victims in this public health epidemic: the children who witness the violence. These usually silent, indirect victims show no physical sign of harm and are commonly overlooked. In urban pediatric practices, clinicians increasingly are told that their young patients hear gunshots outside their homes, witness shootings on the playground, or have a family member (often an older sibling) involved with violence. Recent studies support this. One of every 10 children attending Boston (Mass) City Hospital pediatric primary care clinic witnessed a shooting or stabbing before the age of 6 years,1 half in the home, half on the streets. The average age of the children in this study was 2.7 years. A survey of elementary-school-aged children
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Negative emotions are reliably associated with poorer health (e.g., Kiecolt-Glaser, McGuire, Robles, & Glaser, 2002), but only recently has research begun to acknowledge the important role of positive emotions for our physical health (Fredrickson, 2003). We examine the link between dispositional positive affect and one potential biological pathway between positive emotions and health-proinflammatory cytokines, specifically levels of interleukin-6 (IL-6). We hypothesized that greater trait positive affect would be associated with lower levels of IL-6 in a healthy sample. We found support for this hypothesis across two studies. We also explored the relationship between discrete positive emotions and IL-6 levels, finding that awe, measured in two different ways, was the strongest predictor of lower levels of proinflammatory cytokines. These effects held when controlling for relevant personality and health variables. This work suggests a potential biological pathway between positive emotions and health through proinflammatory cytokines. (PsycINFO Database Record (c) 2015 APA, all rights reserved).