Walking Green: Developing an Evidence Base for Nature Prescriptions

Cardiovascular response to brisk walking on different surfaces in an innovative senior playground: a randomized trial in older adults

Brisk walking is a simple exercise for older adults. We aimed to assess the cardiovascular response to a short bout of brisk walking on walking loops in an innovative senior playground in Thailand. Twenty older adults were randomly assigned to brisk walking on artificial turf (AT group, n = 10) or an uneven surface (US group, n = 10). We assessed cardiovascular parameters, average walking speed, and rate of perceived exertion. Blood pressure, heart rate, rate-pressure product, and rate perceived exertion were significantly increased, while the mean RR interval of heart rate variability was significantly decreased in both AT and US groups after exercise compared with pre-exercise (p < 0.05). A greater change in systolic blood pressure was observed in the US group than in the AT group (p < 0.05). These data indicated that brisk walking on AT and US increases cardiovascular response. Our findings provide information on planning exercise programs for older adults.

Affective Responses to Acute Exercise: A Meta-Analysis of the Potential Beneficial Effects of a Single Bout of Exercise on General Mood, Anxiety, and Depressive Symptoms

OBJECTIVE

Acute exercise elicits various biobehavioral and psychological responses, but results are mixed with regard to the magnitude of exercise-induced affective reactions. This meta-analysis examines the magnitude of general mood state, anxiety, and depressive symptom responses to acute exercise while exploring exercise protocol characteristics and background health behaviors that may play a role in the affective response.

METHODS

A total of 2770 articles were identified from a MEDLINE/PubMed search and an additional 133 articles from reviews of reference sections. Studies had to have measured general mood before the acute exercise bout and within 30 minutes after exercise completion. Effect sizes were estimated using Hedges' g , with larger values indicating improvement in the outcome measure.

RESULTS

A total of 103 studies were included presenting data from 4671 participants. General mood state improved from preexercise to postexercise ( g = 0.336, 95% confidence interval [CI] = 0.234-0.439). Anxiety ( g = 0.497, 95% CI = 0.263-0.730) and depressive symptoms ( g = 0.407, 95% CI = 0.249-0.564) also improved with exercise. There was substantial and statistically significant heterogeneity in each of these meta-analyses. This heterogeneity was not explained by differences in participants' health status. Meta-regression analyses with potential moderators (intensity of exercise, mode of exercise, usual physical activity level, or weight status of participants) also did not reduce the heterogeneity.

CONCLUSION

This meta-analysis shows significantly improved general mood, decreased anxiety, and lower depressive symptoms in response to an acute bout of exercise. There was substantial heterogeneity in the magnitude of the effect sizes, indicating that additional research is needed to identify determinants of a positive affective response to acute exercise.

Developing a hope-focused intervention to prevent mental health problems and improve social outcomes for young women who are not in education, employment, or training (NEET): A qualitative co-design study in deprived coastal communities in South-East England

Young women who are not in education, employment, or training (NEET) experience poorer health and social outcomes compared to non-NEET young women and to NEET young men, especially in deprived areas with intersecting inequalities. The evidence on effective public health approaches is scarce. Interventions that target hope, which NEET young women notably lack, offer a promising theory-driven and intuitive means to prevent mental health problems and improve social outcomes. Hope can be defined as a goal-focused mindset comprising self-agency (motivation and self-belief) and pathways (identifying routes to achieving goals). Hope is implicated in a variety of evidence-based psychosocial interventions for young people, but is not directly targeted by existing prevention programmes for NEET populations. The current study used a phased qualitative research design and participatory methods to model a hope-focused intervention for NEET young women. Phase 1 investigated population needs and intervention parameters through semi-structured interviews with 28 key informants living or working in disadvantaged coastal communities in South-East England. The sample comprised eight NEET young women, four family members, and 16 practitioners from relevant support organisations. Phase 2 refined intervention parameters and outcomes through co-design sessions with four NEET young women, followed by a theory of change workshop with 10 practitioners. The resulting intervention model is articulated as a mentor-supported, in-person psychosocial intervention that builds hope by enhancing positive sense of self and time spent in meaningful activities, before explicitly teaching the skills needed to identify, set, and pursue personally meaningful goals.

The economics of nature's healing touch: A systematic review and conceptual framework of green space, pharmaceutical prescriptions, and healthcare expenditure associations

Green spaces play a crucial role in promoting sustainable and healthy lives. Recent evidence shows that green space also may reduce the need for healthcare, prescription medications, and associated costs. This systematic review provides the first comprehensive assessment of the available literature examining green space exposure and its associations with healthcare prescriptions and expenditures. We applied Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines to search MEDLINE, Scopus, and Web of Science for observational studies published in English through May 6, 2023. A quality assessment of the included studies was conducted using the Office of Health Assessment and Translation (OHAT) tool, and the Grading of Recommendations, Assessment, Development, and Evaluations (GRADE) assessment was used to evaluate the overall quality of evidence. Our search retrieved 26 studies that met the inclusion criteria and were included in our review. Among these, 20 studies (77 % of the total) showed beneficial associations of green space exposure with healthcare prescriptions or expenditures. However, most studies had risks of bias, and the overall strength of evidence for both outcomes was limited. Based on our findings and related bodies of literature, we present a conceptual framework to explain the possible associations and complex mechanisms underlying green space and healthcare outcomes. The framework differs from existing green space and health models by including upstream factors related to healthcare access (i.e., rurality and socioeconomic status), which may flip the direction of associations. Additional research with lower risks of bias is necessary to validate this framework and better understand the potential for green space to reduce healthcare prescriptions and expenditures.

Effects of virtual exposure to urban greenways on mental health

Urban greenways (UGW) are increasingly recognized as vital components of urban green infrastructure (UGI). While existing research has provided empirical evidence on the positive impacts of UGW on physical health, studies focusing on the effects on mental health remain limited. Moreover, previous investigations predominantly compare UGW as a whole with other built environments, neglecting the influence of specific vegetation designs along UGW on mental health. To address this research gap, we conducted a randomized controlled experiment to examine the impact of vegetation design along UGW on stress reduction and attention restoration. A total of 94 participants were randomly assigned to one of four UGW conditions: grassland, shrubs, grassland and trees, or shrubs and trees. Utilizing immersive virtual reality (VR) technology, participants experienced UGW through a 5-min video presentation. We measured participants' subjective and objective stress levels and attentional functioning at three time-points: baseline, pre-video watching, and post-video watching. The experimental procedure lasted approximately 40 minutes. Results of the repeated-measures ANOVA revealed that participants experienced increased stress and mental fatigue after the stressor and decreased levels following the UGW intervention. Furthermore, between-group analyses demonstrated that the shrubs group and the grassland and trees group exhibited significantly greater stress reduction than the grassland group. However, there are no significant differences in attention restoration effects between the four groups. In conclusion, virtual exposure to UGW featuring vegetation on both sides positively affected stress reduction and attention restoration. It is recommended that future UGW construction incorporates diverse vegetation designs, including shrubs or trees, instead of solely relying on grassland. More research is needed to explore the combined effects of shrubs and trees on mental health outcomes.

Predictors of sustained physical activity: behaviour, bodily health, and the living environment

This study examined the determinants of sustained physical activity. Eighty-four participants undertook a 7-weeks walking regime (i.e., a 1-h biometrically-monitored walk, at least 5 days/week), with bioelectrical impedance (BIA) and total cholesterol capillary blood measurements performed before and after programme. To investigate behavioural habit formation, 7 weeks after walking termination, all participants were interviewed and (health) re-tested. Data were modelled with an artificial neural network (ANN) cascading algorithm. Our results highlight the successful prediction of continued physical activity by considering one's physical fitness state, the environmental living context, and risk for cardiovascular disease. Importantly, those artificial neural network models also taking body mass index (BMI) and blood cholesterol as predictors excel at predicting walking continuation (i.e., predictions with 93% predictability). These results are first to highlight the type and importance of available physiological drivers in maintaining a sustained physical activity regime such as walking. They are discussed within the framework of habit formation and the nowadays health and/or wellbeing focus.

Climate change and mental health: Global challenges for psychosocial resilience and recovery

OBJECTIVE

As the greatest global challenge of our time, climate change is not only an ecological crisis but also a humanitarian one. Climate action is a defining opportunity to not only collectively mend ecological health and biodiversity but also to advance psychosocial resilience and social cohesion. This essay aims to understand the interconnectedness between climate change and mental health, as well as explore ways in which this can be transformed into a mobilising force.

CONCLUSIONS

The ramifications of climate change on mental health are complex, and there continues to be expanding knowledge on this through research undertaken out of heightening urgency. With knowledge of this, global recovery will require meaningful and transformative action that addresses the interconnection between climate change, mental health, and social injustice.

Resilience After Trauma in Kosovo and Southeastern Europe: A Scoping Review

Most people who experience trauma want to thrive and often find paths to well-being and healthy functioning. This scoping review explores the existing evidence on adversity and resilience in southeastern European countries, focusing on Kosovo. There is a lack of research on trauma and resilience in cultures outside the US and Western Europe. The paper provides a brief cultural and historical overview of this region and the collectivist cultures found there. We draw from a range of interdisciplinary literatures to identify key strengths that have the potential to improve health outcomes for trauma victims in this region. Overall, 42 papers from PsycInfo and PubMed were identified, using keywords such as "resilience" or "health" and "Kosovo," "Balkans," and "Southeastern Europe." Findings from this scoping review show that different cultural values, norms, and societal ecologies impact resilience within these societies. Some strengths, such as social support and sense of purpose, echoed similar research in the US and Western Europe. There was also evidence that factors such as dignity, family solidarity, social activism, and nationwide meaning-making are strengths associated with resilience for these collectivist societies of southeastern Europe. We also consider the implications of the results for other post-conflict societies. Finally, findings from this review call for culturally sensitive strength-based perspectives in promoting health and well-being after the high dosages of trauma common in this region.

A systematic review of the anxiety-alleviation benefits of exposure to the natural environment

Research suggests that exposure to natural environments can be beneficial for health, such as reducing physical illness and improving mood and cognitive ability. The potential benefits of nature have come into focus at a time when mental health issues are growing globally. Here, we have selected 24 studies from four databases for meta-analysis to explore the effects of exposure to the natural environment on the anxiety of the human body and summarize the influencing factors on the anxiety relief effect. A random-effect meta-analysis of anxiety state changes before and after exposure to natural environment shows that natural exposure effectively alleviated human anxiety (SMD -1.28, 95% CI: -1.65 to -0.92). The overall quality of the included papers, assessed using the PEDro scale, is considered to vary considerably, but most of the papers are rated between 4 and 7 which is considered fair or good. In addition, we have also investigated the potential moderators of anxiety-relieving effects of the nature. Our results shows that the age and exposure time of the subjects are related to the effect of anxiety relief. The results of the subgroup analysis of moderators prove that compared with the middle-aged people (SMD -0.63, 95% CI: -1.13 to -0.12), young people (SMD -1.50, 95% CI: -1.90 to -1.10) get better anxiety alleviation effect in the natural environment. In terms of exposure time, compared with 0.5-2 h (SMD -0.18, 95% CI: -0.59 to -0.23) and >2 h (SMD -0.84, 95% CI: -1.40 to -0.27) exposure periods, subjects get the maximum anxiety relief benefit when they spent <0.5 h (SMD -1.60, 95% CI: -1.93 to -1.27) in the natural environment. However, the quality of the included studies varies greatly and there is a significant heterogeneity in the meta-analysis. Study location, natural environment type and other moderator factors have no obvious correlation with anxiety-alleviation effect of the nature. A higher quality and more comprehensive study needs to be carried out to find out more moderators about the effects of the natural environment on anxiety alleviation. Further experimental studies should also be conducted to determine the mechanism by which natural exposure reduces anxiety so as to provide strong support for the construction and improvement of healthy natural environment.

Psychological and functional outcomes following a randomized controlled trial of surf and hike therapy for U.S. service members

Introduction

Exercise-based interventions have established benefits for the treatment of depression and other psychological outcomes; however, limited data exist evaluating psychological, social, and functional outcomes for exercise outdoors.

Methods

The current study sought to expand knowledge about the breadth of effects following outdoor exercise interventions by using data from a randomized control trial comparing Surf and Hike Therapy among 96 U.S. active duty service members with major depressive disorder (MDD). Assessments examining psychological symptoms and functioning were completed before and after the 6-week programs, and 3 months following program completion. Participants also completed assessments before and after each exercise session. Multilevel modeling was used to determine whether psychological and functional outcomes (anxiety, positive and negative affect, resilience, pain, and physical and social functioning) improved for service members receiving Surf or Hike Therapy, and whether improvements differed by intervention.

Results

Study findings showed improved anxiety (p < 0.001), negative affect (p < 0.001), psychological resilience (p = 0.013), and social functioning (p < 0.001) following program participation, with no differences by intervention. Positive affect, pain, and physical functioning did not significantly improve after the program. Within sessions, positive affect (p < 0.001) and pain (p = 0.036) changed, and to a greater extent for those in the Surf Therapy condition.

Conclusion

Study results suggest that both Surf Therapy and Hike Therapy can improve psychological symptoms and social functioning impairments that commonly co-occur among service members with MDD, but Surf Therapy may provide enhanced immediate effects on positive affect and pain.

Clinical trial registration

ClinicalTrials.gov, NCT03302611.

Effect of nature prescriptions on cardiometabolic and mental health, and physical activity: a systematic review

Nature prescriptions are gaining popularity as a form of social prescribing in support of sustainable health care. This systematic review and meta-analysis aims to synthesise evidence on the effectiveness of nature prescriptions and determine the factors important for their success. We searched five databases from inception up to July 25, 2021. Randomised and non-randomised controlled studies featuring a nature prescription (ie, a referral or an organised programme, by a health or social professional, to encourage spending time in nature) were included. Two reviewers independently conducted all steps of study selection; one reviewer collected summary data from published reports and conducted the risk of bias assessment. Random-effect DerSimonian-Laird meta-analyses were conducted for five key outcomes. We identified 92 unique studies (122 reports), of which 28 studies contributed data to meta-analyses. Compared with control conditions, nature prescription programmes resulted in a greater reduction in systolic blood pressure (mean difference -4·82 mm Hg [-8·92 to -0·72]) and diastolic blood pressure (mean difference -3·82 mm Hg [-6·47 to -1·16). Nature prescriptions also had a moderate to large effect on depression scores (post-intervention standardised mean difference -0·50 [-0·84 to -0·16]; change from baseline standardised mean difference -0·42 [-0·82 to -0·03]) and anxiety scores (post-intervention standardised mean difference -0·57 [-1·12 to -0·03]; change from baseline standardised mean difference -1·27 [-2·20 to -0·33]). Nature prescriptions resulted in a greater increase in daily step counts than control conditions (mean difference 900 steps [790 to 1010]) but did not improve weekly time of moderate physical activity (mean difference 25·90 min [-10·26 to 62·06]). A subgroup analysis restricted to studies featuring a referring institution showed stronger effects on depression scores, daily step counts, and weekly time of moderate physical activity than the general analysis. Beneficial effects on anxiety and depression scores were mainly provided by interventions involving social professionals whereas beneficial effects on blood pressures and daily step counts were provided mainly by interventions involving health professionals. Most studies have a moderate to high risk of bias. Nature prescription programmes showed evidence of cardiometabolic and mental health benefits and increases in walking. Effective nature prescription programmes can involve a range of natural settings and activities and can be implemented via social and community channels, in addition to health professionals.

The effects of forest bathing on psychological well-being: A systematic review and meta-analysis

Globally, around half (55%) of the population live in fast-paced urban settings where many people find it challenging to manage their stress and respond to crises with a positive mindset. This resulted in prolonged distress where anxiety and fatigue caused physical and mental health concerns. Nature walks involving immersive exposure in the forest, and green spaces have been posited to offer physiological and psychological benefits. Therefore, in this systematic review, we evaluated the effects of forest bathing on psychological and physiological outcomes. We searched four English and five non-English databases (Chinese and Korean) for peer-reviewed studies published between January 2000 and March 2021. This review adhered to the recommendations of the Preferred Reporting Items for Systematic Reviews and Meta-analysis Statement 2020. The primary outcomes explored in this review were mainly psychological, including anxiety, depression, mood and quality of life. The secondary outcomes were physiological outcomes such as blood pressure and heart rate. We conducted a meta-analysis on each outcome using the random-effects model. Heterogeneity was assessed by the I² statistic. Thirty-six articles (21 in English, 3 in Chinese and 12 in Korean) with 3554 participants were included in this review. Our meta-analysis suggested that forest bathing can significantly reduce symptoms of depression and anxiety. However, we did not observe as many benefits in physiological outcomes. Against the background of the negative effects of urbanization on mental well-being, this review highlighted the potential therapeutic role of forests in the contemporary world, lending further evidence-based support for forest conservation.

Sea swimming and snorkeling in tropical coastal blue spaces and mental well-being: Findings from Indonesian island communities during the COVID-19 pandemic

The COVID-19 pandemic has considerable mental health impacts. Immersive nature-based interventions, such as swimming or snorkeling, may help mitigate the global mental health crisis caused by the pandemic. To investigate this, we collected cross-sectional data from residents of coastal villages (n = 308) in Kepulauan Selayar, Indonesia. Analysis of Covariance (ANCOVA) was used with mental well-being as the outcome variable, operationalized as the Mental Component Summary (MCS) scores from the SF-12 (12-item Short Form Health Survey). After adjusting for covariates, the activity of sea swimming or snorkeling was found to be significantly associated with better mental well-being (η² = 0.036; p < 0.01). Predictive margins analysis revealed that those who engaged in sea swimming or snorkeling for one to three days a week gained a 2.7 increase in their MCS scores, compared to those who did not. A non-linear dose-response relationship was detected: for those swimming or snorkeling more than three days per week, there was only an increase of 1.7 MCS score compared to the 0-day. Overall this study contributes to the expanding of evidence base, showing that interactions with blue spaces can be beneficial for mental health, especially in a potentially stressful time such as the current pandemic.

Management implications

The positive association between the activity of swimming or snorkeling in open seas and the mental well-being of rural coastal communities in Indonesia during the COVID-19 pandemic indicates that access to coastal blue spaces is important in a time of uncertainties and high stress. Ensuring that local communities have continuous access to these spaces is the key challenge for all relevant stakeholders, particularly in light of the growing privatization of the local coastal environment for the sake of tourism. However, considering the importance that these blue spaces hold for the mental well-being of local communities, intensive dialogue amongst these stakeholders must be pursued to ensure that the development of the area does not jeopardize the collective well-being of the people already living there.

A randomized controlled trial of surf and hike therapy for U.S. active duty service members with major depressive disorder

BACKGROUND

Major depressive disorder (MDD) is the most prevalent mental health disorder worldwide, including among U.S. service members. In addition to evidence-based treatments, activity-based approaches have been shown to effectively treat depressive symptoms, particularly when they occur in the natural environment.

METHODS

This study compared two activity-based interventions, Surf Therapy and Hike Therapy, on depression outcomes among 96 active duty service members with MDD. Participants were randomized to 6 weeks of Surf or Hike Therapy. Clinician-administered and self-report measures were completed at preprogram, postprogram, and 3-month follow-up. A brief depression/anxiety measure was completed before and after each activity session.

RESULTS

Multilevel modeling results showed that continuous depression outcomes changed significantly over time (ps < .001). Although service members in Hike Therapy reported higher average depression scores than those in Surf Therapy, the trajectory of symptom improvement did not significantly differ between groups. Regarding MDD diagnostic status, there were no significant differences between the groups at postprogram (p = .401), but Surf Therapy participants were more likely to remit from MDD than were those in Hike Therapy at the 3-month follow-up (p = .015).

LIMITATIONS

The sample consisted of service members, so results may not generalize to other populations. Most participants received concurrent psychotherapy or pharmacotherapy, and, although statistically accounted for, results should be interpreted in this context.

CONCLUSIONS

Both Surf and Hike Therapies appear to be effective adjunctive interventions for service members with MDD. Research is needed to examine the effectiveness of these therapies as standalone interventions.

TRIAL REGISTRATION

Clinical trials registration number NCT03302611; First registered on 05/10/2017.

Healthy lifestyles and wellbeing reduce neuroinflammation and prevent neurodegenerative and psychiatric disorders

Since the mid-20th century, Western societies have considered productivity and economic outcomes are more important than focusing on people's health and wellbeing. This focus has created lifestyles with high stress levels, associated with overconsumption of unhealthy foods and little exercise, which negatively affect people's lives, and subsequently lead to the development of pathologies, including neurodegenerative and psychiatric disorders. Prioritizing a healthy lifestyle to maintain wellbeing may slow the onset or reduce the severity of pathologies. It is a win-win for everyone; for societies and for individuals. A balanced lifestyle is increasingly being adopted globally, with many doctors encouraging meditation and prescribing non-pharmaceutical interventions to treat depression. In psychiatric and neurodegenerative disorders, the inflammatory response system of the brain (neuroinflammation) is activated. Many risks factors are now known to be linked to neuroinflammation such as stress, pollution, and a high saturated and trans fat diet. On the other hand, many studies have linked healthy habits and anti-inflammatory products with lower levels of neuroinflammation and a reduced risk of neurodegenerative and psychiatric disorders. Sharing risk and protective factors is critical so that individuals can make informed choices that promote positive aging throughout their lifespan. Most strategies to manage neurodegenerative diseases are palliative because neurodegeneration has been progressing silently for decades before symptoms appear. Here, we focus on preventing neurodegenerative diseases by adopting an integrated "healthy" lifestyle approach. This review summarizes the role of neuroinflammation on risk and protective factors of neurodegenerative and psychiatric disorders.

What is the impact of nature on human health? A scoping review of the literature

Background

The burden of non-communicable diseases (including poor mental health) is increasing, and some practitioners are turning to nature to provide the solution. Nature-based interventions (NBIs) could offer cost-effective solutions by reconnecting individuals with nature, but the success of these interventions depends partially on the way in which people engage with blue and green spaces.

Methods

We conducted a scoping review in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) and Cochrane guidelines to establish the evidence base for treating poor mental and physical health with NBIs. We searched five databases and the grey literature. Exposure was the active engagement with natural environments. The primary outcome was mental health and the secondary outcome was physical health defined using established metrics. All data were extracted to a charting table and reported as a narrative synthesis.

Results

952 studies were identified, of which 39 met the inclusion criteria. 92% demonstrated consistent improvements across any health outcome where individuals engaged with natural outdoor environments. Mental health outcomes improved across 98% of studies while physical and cognitive health outcomes showed improvement across 83% and 75% of studies respectively. Additionally, we identified 153 factors affecting engagement with nature, 78% of which facilitated engagement compared with 22% that reduced engagement. Aspects such as the sense of wilderness, accessibility, opportunities for physical activity and the absence of noise/ air pollution all increased engagement.

Conclusions

Further research (accompanied by a global improvement in study design) is needed to establish the magnitude and relative effect of nature-based interventions, and to quantify the compounding effect of factors that improve engagement with green and blue spaces. Nevertheless, this review has documented the increasing body of evidence in support of NBIs as effective tools to improve mental, physical, and cognitive health outcomes, and highlighted key factors that improve engagement with the natural world.

Registration

Open Science Framework: https://doi.org/10.17605/OSF.IO/8J5Q3.

The effects of walking in nature on negative and positive affect in adult psychiatric outpatients with major depressive disorder: A randomized-controlled study

BACKGROUND

While walking in nature has been shown to improve affect in adults from the community to a greater extent than walking in urban settings, it is unknown whether such benefits apply to individuals suffering from depression. Using a parallel group design, this randomized controlled trial examined the effects of a single walk in nature versus urban settings on negative and positive affect in adult psychiatric outpatients diagnosed with major depressive disorder (MDD).

METHOD

Participants recruited from a psychiatric outpatient clinic for adults with MDD were randomly assigned to a nature or urban walk condition. Thirty-seven adults (mean age = 49 years) completed a single 60-minute walk. Negative and positive affect were assessed using The Positive and Negative Affect Schedule or PANAS at 6 time points: before the walk, halfway during the walk, immediately post-walk, at home before bedtime, 24 h post-walk, and 48 h post-walk.

RESULTS

Controlling for baseline levels of affect before the walk, individuals who walked in nature experienced overall lower levels of negative affect, F(1, 35.039) = 4.239, p = .047, compared to those who walked in urban settings. Positive affect did not differ across walk conditions.

LIMITATIONS

The generalizability of results are limited by the small sample size and the presence of more female than male participants.

CONCLUSIONS

Walking in nature might be a useful strategy to improve negative affect in adults with MDD. Future research should investigate different ways to integrate the beneficial effects of nature exposure into existing treatment plans for psychiatric outpatients with MDD.

Is altitude a determinant of the health benefits of nature exposure? A systematic review and meta-analysis

Introduction

Nature exposure is a widely accepted option for promoting public health owing to the recent surge of scientific evidence. However, the actual settings to facilitate this initiative is yet to be extensively reviewed. In this systematic review, we have aimed to provide an up-to-date summary of interventional studies investigating the psycho-physiological effects of forests and urban forests, including details on their physical settings, and investigate an effect-modifying role of altitude and summarize data on the magnitude and shape of the association.

Methods

A keyword search using five electronic academic databases (PubMed, Embase, PsycINFO, Web of Science, and Scopus) was conducted to identify relevant articles published in English from the inception year to the end of February 2022. The methodological quality was evaluated using the ROBINS-I or ROB2 tool, depending on the study design. Meta-regression and random effects model were jointly used to examine the relationship between altitude and health outcomes.

Results

We included 27 eligible studies and 31 cases extracted from 19 studies were used for the meta-analysis. In the meta-regression, we observed a non-linear association between altitude and psycho-physiological effects. Altitude had a positive quadratic association with anxiety (p < 0.000, adjusted R ² = 96.79%), depression (p < 0.000, adjusted R ² = 98.78%), and fatigue (p < 0.000, adjusted R ² = 64.74%) alleviating effects. Conversely, altitude demonstrated a negative non-linear association with the blood pressure-lowering effect (p = 0.009, adjusted R ² = 32.83%). Additionally, the thermal index (THI) and illuminance (lx) levels were significantly associated with effect sizes of psychological restoration.

Discussion

This review provides moderate-certainty evidence for an effect-modifying role of altitude. The meta-regression results suggested the optimal and minimal altitude ranges for psychological restoration and physiological relaxation, respectively. Despite some limitations, the study findings provide a significant basis for utilizing altitude, which is easily accessible and simple, to promote the health benefits of nature-based initiatives.

Systematic review registration

https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42022310894, identifier: CRD42022310894.

The impact of black carbon (BC) on mode-specific galvanic skin response (GSR) as a measure of stress in urban environments

Previous research has shown that walking and cycling could help alleviate stress in cities, however there is poor knowledge on how specific microenvironmental conditions encountered during daily journeys may lead to varying degrees of stress experienced at that moment. We use objectively measured data and a robust causal inference framework to address this gap. Using a Bayesian Doubly Robust (BDR) approach, we find that black carbon exposure statistically significantly increases stress, as measured by Galvanic Skin Response (GSR), while cycling and while walking. Augmented Outcome Regression (AOR) models indicate that greenspace exposure and the presence of walking or cycling infrastructure could reduce stress. None of these effects are statistically significant for people in motorized transport. These findings add to a growing evidence-base on health benefits of policies aimed at decreasing air pollution, improving active travel infrastructure and increasing greenspace in cities.

Cognitive-Emotional Benefits of Weekly Exposure to Nature: A Taiwanese Study on Young Adults

Empirical evidence of nature’s benefits to cognitive and emotional well-being is emerging. In this study, 48 Taiwanese young adults (24 indoors and 24 outdoors in urban greenspace) completed four weekly 45 min exposure sessions. The study explores whether the outdoor group surpasses the indoor group in cognitive and emotional well-being and nature connectedness. There were no significant differences for the indoor group across different measurements of rumination and connectedness to nature. However, the outdoor group displayed a significant reduction in rumination post-test compared to the one week prior and the first session. Similarly, for sessions two, three, and four and one month post-test, the outdoor group’s connectedness to nature was significantly higher than pre-test. Specific autobiographical memory was enhanced while overgeneral autobiographic memory was reduced during the third and fourth sessions, though these changes were not sustained at one-month follow-up. Surprisingly, both groups yielded similar results in decreased depression, anxiety, and stress. A significantly higher number of outdoor group participants had employed nature exposure for coping with stress or emotions after the program. We discuss the implications of this for counseling services for young adults and highlight future research possibilities, including formulating a nature-exposure protocol and a program evaluation for consolidating evidence-based nature prescription.

Associations between neighborhood built, social, or toxicant conditions and child externalizing behaviors in the Detroit metro area: a cross-sectional study of the neighborhood ‘exposome’

Background

The specific ‘active ingredients’ through which neighborhood disadvantage increases risk for child psychopathology remains unclear, in large part because research to date has nearly always focused on poverty to the exclusion of other neighborhood domains. The objective of this study was to evaluate whether currently assessed neighborhood built, social, or toxicant conditions were associated with child externalizing psychopathology outcomes separately, and in a combined model, using data from the Detroit-metro county area.

Methods

We conducted principal components analyses for built, social, or toxicant conditions. Next, we fitted separate multiple regression models for each of the child externalizing psychopathology measures (oppositional defiant and conduct problems) as a function of built, social, or toxicant components.

Results

We found that built features (more non-profits, churches, and alcohol outlets, and less agriculture and vacant properties) were associated with conduct problems, while toxicant conditions (high percent industrial, toxins released and number of pre-1978 structures) were associated with oppositional defiance problems. There was no significant association between greenspace or social conditions and child externalizing outcomes. When examined simultaneously, only the significant independent association between built conditions and conduct problems remained.

Conclusions

Built, social, and toxicant neighborhood conditions are not interchangeable aspects of a given neighborhood. What’s more, built features are uniquely associated with child externalizing outcomes independently of other neighborhood characteristics. Future research should consider how changes in the built conditions of the neighborhood (e.g., development, decay) serve to shape child externalizing behaviors, with a focus on identifying potentially actionable elements.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12889-022-13442-z.

A Meta-Analysis of Emotional Evidence for the Biophilia Hypothesis and Implications for Biophilic Design

The biophilia hypothesis posits an innate biological and genetic connection between human and nature, including an emotional dimension to this connection. Biophilic design builds on this hypothesis in an attempt to design human-nature connections into the built environment. This article builds on this theoretical framework through a meta-analysis of experimental studies on the emotional impacts of human exposure to natural and urban environments. A total of 49 studies were identified, with a combined sample size of 3,201 participants. The primary findings indicated that exposure to natural environments had a medium to large effect on both increasing positive affect and decreasing negative affect. This finding supported the anticipated emotional dimension of the biophilia hypothesis and lends credibility to biophilic design theory. Evidence was revealed in support of the affective/arousal response model. Immersion in environments indicated a larger effect size than laboratory simulation of environments. Methodological recommendations for future experimental research were few, however the Positive and Negative Affect Schedule (PANAS) outcome measure was recommended as a measure of both positive and negative affect for further studies. A combination measurement of stress related outcome variables was proposed to further explore the affective/arousal response model and its potential relationship to the biophilia hypothesis. The meta-analysis provides evidence for fundamental theories regarding human-nature connection, while revealing gaps in current knowledge.

What Activities in Forests Are Beneficial for Human Health? A Systematic Review

Over the past decade, clinical trials of forest-based interventions have increased, leading to their recognition as preventive medicine. However, little is known about the differences in health effects according to the activity characteristics of interventions. This study aimed to understand the types of activities and their associated health effects to identify differences in health effects between activities. PubMed, PsycINFO, Web of Science, and Scopus databases were searched, and methodological quality was assessed using Cochrane ROB2. A total of 32 randomized controlled trials (RCTs) met the eligibility criteria. Health outcomes were collected from 6264 participants aged 6-98 years, and the sample size was 12-585. The Interventions were walking (n = 21), staying (n = 7), exercise (n = 4), indirect exposure (n = 4), and the activity time was between 10 and 240 min. Overall, walking showed consistent positive health effects, and there were differences in effects on anxiety and depression, cognitive function, stress hormone, and inflammation according to the activity. However, most of the included studies had a high risk of bias, and interventions were limited to specific activities, durations, and frequencies. Although a few limitations remain, the findings in this study are of great significance in providing the basis for the design of forest-based interventions.

Can Different Forest Structures Lead to Different Levels of Therapeutic Effects? A Systematic Review and Meta-Analysis

In recent decades, forests have expanded from natural resources for conservation and production to health-promoting resources. With the growing body of evidence supporting the therapeutic effects of forests, the number of investigations on the relationship between forest characteristics and therapeutic effects have increased. However, quantitative synthesis of primary studies has rarely been conducted due to a limited number of health studies including forest description and high heterogeneity of forest variables. In this study, we conducted a systematic review and meta-analysis to evaluate the relationship between the forest structure and the therapeutic effect. We systematically searched the studies examining the therapeutic effects of forests with different stand density and canopy density and synthesized the results. As a result of subgroup analysis, we found that stand density modifies the therapeutic effects. Emotional and cognitive restoration showed greatest improvement in low-density forests with a stand density of less than 500/ha and the therapeutic effects diminish as the stand density increases. The impact of canopy density was not found due to a lack of studies reporting canopy density. Although some limitations remain, the findings in this study have great significance in providing the basis for establishing management strategies of forests for therapeutic use.

Associations between Nature Exposure and Health: A Review of the Evidence

There is extensive empirical literature on the association between exposure to nature and health. In this narrative review, we discuss the strength of evidence from recent (i.e., the last decade) experimental and observational studies on nature exposure and health, highlighting research on children and youth where possible. We found evidence for associations between nature exposure and improved cognitive function, brain activity, blood pressure, mental health, physical activity, and sleep. Results from experimental studies provide evidence of protective effects of exposure to natural environments on mental health outcomes and cognitive function. Cross-sectional observational studies provide evidence of positive associations between nature exposure and increased levels of physical activity and decreased risk of cardiovascular disease, and longitudinal observational studies are beginning to assess long-term effects of nature exposure on depression, anxiety, cognitive function, and chronic disease. Limitations of current knowledge include inconsistent measures of exposure to nature, the impacts of the type and quality of green space, and health effects of duration and frequency of exposure. Future directions include incorporation of more rigorous study designs, investigation of the underlying mechanisms of the association between green space and health, advancement of exposure assessment, and evaluation of sensitive periods in the early life-course.

Effect of Nature Walks on Depression and Anxiety: A Systematic Review

The benefits of nature for our health have been an increasing research focus in recent years. In the context of a global increase in mental health diagnoses, the potential health benefits of nature have attracted attention. One practical nature treatment is to walk in nature. However, evidence for this practice on mental health has not been comprehensively appraised to date. This systematic review synthesized the effects of nature walks for depression and anxiety, and evaluated the methodological rigor of studies. Academic databases including ProQuest, PsycINFO, Science Direct, and Google Scholar were utilized to identify eligible articles, which were examined using the Newcastle–Ottawa Scale. Of 385 articles initially retrieved, 12 studies met all the eligibility criteria (nine pre-post within-subject studies, two quasi-experimental studies, and one experimental between-subjects study). These studies demonstrated that nature walks were effective for state anxiety but not generalized anxiety and the effects for depression were inconsistent. Findings indicate that nature walks may be effective for mental health, especially for reducing state anxiety. However, the quality of the included studies varied, and sample sizes were small, suggesting a need for more rigorous and large-scale research.

Natural or Urban Campus Walks and Vitality in University Students: Exploratory Qualitative Findings from a Pilot Randomised Controlled Study

Despite extensive evidence of the restorative effects of nature, the potential vitalizing effects of connecting with nature are yet understudied, particularly in higher education settings. University students face high levels of stress and anxiety, and may benefit from nature-based interventions that enhance positive states such as vitality. Using preliminary data from a pilot randomized controlled study with qualitative interviews, we explored the psychological experiences associated with a brief walk either in nature or an urban environment in a sample of 13 university students. The qualitative thematic analysis revealed that walking in nature was a more energizing and vitalizing experience than the urban walk. The nature walk was also found to have both affective and cognitive enhancing effects on participants. Our study highlights the usefulness of exploring subjective psychological experiences of interacting with nature, as well as supporting its restorative potential. Implications for further research and interventions are discussed.

The Relationship between Nature Deprivation and Individual Wellbeing across Urban Gradients under COVID-19

Lockdown aiming at slowing COVID-19 transmission has altered nature accessibility patterns, creating quasi-experimental conditions to assess if retracted nature contact and perceived nature deprivation influence physical and emotional wellbeing. We measure through on-line survey methods (n = 529) how pandemic mandates limiting personal movement and outdoor nature access within the United States affect self-assessed nature exposure, perceived nature deprivation, and subsequent flourishing as measured by the Harvard Flourishing Index. Results indicate that perceived nature deprivation strongly associates with local nature contact, time in nature, and access to municipal nature during the pandemic, after controlling for lockdown mandates, job status, household composition, and sociodemographic variables. Our hypothesis is that individuals with strong perceived nature deprivation under COVID-19 leads to diminished wellbeing proved true. Interaction models of flourishing showed positive modification of nature affinity with age and qualitative modification of nature deprivation with race. Our results demonstrate the potential of local nature contact to support individual wellbeing in a background context of emotional distress and social isolation, important in guiding public health policies beyond pandemics.

The Effects of Green and Urban Walking in Different Time Frames on Physio-Psychological Responses of Middle-Aged and Older People in Chengdu, China

Nighttime walking is becoming a popular exercise for many middle-aged and older people in Asian countries. However, the health benefits of nighttime walking in urban areas and green spaces are still unclear. This study evaluated the physiological and psychological responses of 48 middle-aged and older people who walked 1.6 km through a green space and an urban area during daytime and nighttime. The Positive and Negative Affect Schedule (PANAS), Profile of Mood States (POMS), Perceived Restorativeness Scale (PRS), and Restorative Outcome Scale (ROS) were employed to measure the psychological responses, and pulse rate and blood pressure (SBP, DBP and MAP) were measured to evaluate the physiological responses. The results showed that the daytime green walking induced psychological improvements and lowered blood pressure (p < 0.05), while the daytime urban walking resulted in slight deterioration of all the measured parameters (p > 0.05). On the other hand, the nighttime green walking induced lowered blood pressure (p < 0.05), whilst the nighttime urban walking resulted in psychological improvements and lowered blood pressure (p < 0.05), and no significant difference was found in any measured parameter between the two nighttime walking groups. In conclusion, urban areas are noisy and irritating in the daytime, and not suitable for walking, but may become pleasurable and attractive at night. The psychological benefits of green walking may decrease at night, and nighttime walking in either an urban area or a green space may achieve similar health benefits. Therefore, we recommend that urban citizens start nighttime walking in a green space or an urban area to keep fit when the air is less polluted.

Physical and mental health effects of repeated short walks in a blue space environment: A randomised crossover study

INTRODUCTION

Blue spaces may benefit mental health and promote physical activity, although the evidence is still scarce. And benefits on physical health are less consistent. The objective of this randomized crossover study was to assess psychological and cardiovascular responses to blue spaces' exposure.

METHODS

A sample of 59 healthy adult office workers was randomly assigned to a different environment (i.e. blue space, urban space, and control site) on 4 days each week, for 3 weeks. For 20 min per day, they either walked along a blue or an urban space or rested at a control site. Before, during and/or after the exposure, we measured self-reported well-being and mood, blood pressure, and heart rate variability parameters. For well-being, we also assessed the duration of these potential effects over time (at least 4 h after exposure).

RESULTS

We found significantly improved well-being and mood responses immediately after walking in the blue space compared with walking in the urban space or when resting in the control site. Cardiovascular responses showed increased activity of the sympathetic nervous system, both during and after walking along the blue and urban spaces. However, cardiovascular responses measured after the walks, showed no statistically significant differences between the blue and the urban space environments.

CONCLUSIONS

Short walks in blue spaces can benefit both well-being and mood. However, we did not observe a positive effect of blue spaces for any of the cardiovascular outcomes assessed in this study.

Study of active neighborhoods in Detroit (StAND): study protocol for a natural experiment evaluating the health benefits of ecological restoration of parks

BACKGROUND

Individuals living in deprived inner cities have disproportionately high rates of cancers, Type 2 diabetes and obesity, which have stress- and physical inactivity-related etiologies. This study aims to quantify effects of ecological park restoration on physical activity, stress and cardio-metabolic health outcomes.

METHODS

The Study of Active Neighborhoods in Detroit is a quasi-experimental, longitudinal panel natural experiment with two conditions (restored park intervention (INT) and control (CNT)) and annual measurements at baseline and 3-years post-restoration. Individuals (sampled within 500 m of an INT/CNT park) serve as the unit of analysis. Restoration (n = 4 parks) involves replacing non-native plants and turf with native plants; creating trails; posting signage; and leading community stewardship events. The CNT condition (n = 5) is an unmaintained park, matched to INT based on specified neighborhood conditions. Recruitment involves several avenues, with a retention goal of 450 participants. Park measures include plant/avian diversity; usage of the park (SOPARC); signs of care; auditory environment recordings; and visual greenness using 360 imagery. Health outcomes include device-based physical activity behavior (primary outcome); salivary cortisol (secondary outcome); and several downstream health outcomes. Exposure to the INT will be assessed through visual contact time and time spent in the park using GPS data. Changes in health outcomes between years and INT versus CNT will be tested using generalized linear (mixed) models.

DISCUSSION

Our study will examine whether restored urban greenspaces increase physical activity and lower stress, with public health planning implications, where small changes in neighborhood greenspaces may have large health benefits in low-income neighborhoods.

STUDY REGISTRATION

Registration: OSF Preregistration registered March 31, 2020. Accessible from https://osf.io/surx7.