Leafier Communities, Healthier Hearts: An Australian Cohort Study of 104,725 Adults Tracking Cardiovascular Events and Mortality Across 10 Years of Linked Health Data

Contact with nature, nature prescriptions, and loneliness: Evidence from an international survey of adults in Australia, India, Singapore, the United Kingdom, and the United States

Evidence to support nature contact and nature prescriptions to reduce loneliness is scant. A total of 2100 individuals took part in a survey conducted in Australia (n = 525, mean age = 34.1), India (n = 526, mean age = 29.5), Singapore (n = 523, mean age = 36.1), the UK (n = 526, mean age = 37.3), and the US (n = 525, mean age = 43.6) in 2022 (overall age range 18-89yrs). Multilevel logistic regressions adjusted for confounding indicated mean levels of overall loneliness tended to be higher in India (Odds Ratio [OR] 1.21, 95% Confidence Interval [95%CI] 0.90-1.62), Singapore (OR = 1.54, 95%CI = 1.15-2.07), the UK (OR = 1.26, 95%CI = 0.96-1.67) and the US (OR = 1.24, 95%CI = 0.94-1.64) compared with Australia. Notable differences were observed by loneliness type, for example, with lower odds of social loneliness (OR = 0.57, 95%CI = 0.41-0.79) and higher odds of emotional loneliness (OR = 1.57, 95%CI = 1.14-2.06) in India compared with Australia. Findings with regards to loneliness and nature contact varied between country. In general, social loneliness was lower in participants who visited natural surroundings regularly (OR = 0.81, 95%CI = 0.61-0.98) and spent two hours or more per week in nature (OR = 0.65, 95%CI = 0.49-0.81). Overall loneliness (OR = 1.98, 95%CI = 1.48-2.47) and emotional loneliness (OR = 2.84, 95%CI = 2.13-3.51) were substantially higher among those who felt having no-one to go with was a barrier to spending time in nature. Emotional loneliness was higher in those who had more time in nature (OR = 1.32, 95%CI = 0.94-1.75) or more frequent visits (OR = 1.24, 95%CI = 0.94-1.49), which may be indicative of selective processes by which some people who feel emotionally lonely seek meaningful sources of connection or solace in natural environments. In sum, these findings highlight potentially important contingencies in how people feel lonely in different countries, and the potential of contact with nature as a means to address this critical issue of modern times. Randomised trials of nature prescription interventions for loneliness co-designed with respect to contrasting cultural, economic, and climatic contexts are needed to ensure programs intended to reconnect people with nature are effective, equitable, and acceptable for everyone.

Contact with nature may be a remedy for loneliness: A nationally representative longitudinal cohort study

BACKGROUND

Nature prescribing - a written recommendation by a health professional for a person to spend more time in nature for health reasons - is being heralded by some as a potential solution to loneliness, defined as a felt deprivation of meaningful connection, companionship, and camaraderie. However, such recommendations currently lack evidence on how much time in natural environments is needed to tackle loneliness and over what timescale.

METHODS

General, emotional, and social loneliness were measured using De Jong Gierveld's 6-item scale in a nationally representative sample of 3043 Australian participants at baseline (October 2020), with 2421 and 2123 completing follow-ups at 4 months (February 2021) and 16 months (February 2022), respectively. Multilevel logistic regressions examined the odds of change in loneliness status between baseline and follow-up in relation to hours spent in nature in the 7 days prior to the baseline survey, adjusting for confounding factors that influence time spent in nature and the risk of feeling lonely.

FINDINGS

Relief from general loneliness in those experiencing it at baseline was 22.4% at month 4 and 29.4% at month 16. The equivalent findings for relief from social loneliness and emotional loneliness were 21.2% and 24.6%, and 34.2% and 41.2% at months 4 and 16, respectively. Incidence of loneliness at 4 months was 21.8% (general), 26.1% (social), and 11.8% (emotional), and at 16 months was 22.7% (general), 25.6% (social), and 12% (emotional). At each time point, the prevalence of loneliness was lower among participants with more time in nature. Just 1-2 h per week in nature (versus <1) was associated with relief from social loneliness at 4 months (Odds Ratio [OR] 1.69, 95%CI 1.10, 2.65) and at 16 months (OR 2.10, 95%CI 1.34, 3.30). Higher odds of relief from emotional loneliness were observed at 3-4 h spent in nature at 4 months (OR 1.84, 95%CI 1.11, 3.06) and at 16 months (OR 1.82, 95%CI 1.09, 3.07). Incidence of loneliness was not associated with nature contact.

INTERPRETATION

Increasing time in nature may an effective non-medical prescription for people who are lonely to find durable relief within a relatively short space of time. Findings from this longitudinal study can inform further investigation through randomised trials of co-designed nature prescriptions targeting relief from loneliness in vulnerable populations.

The co-benefits of climate change mitigation strategies on cardiovascular health: a systematic review

Background

Climate change is a significant threat to global human health and a leading cause of premature death. Global warming, leading to more extreme weather (in particular extreme heat events), and air pollution has been associated with increased cardiovascular disease (CVD) morbidity and mortality. According to the Global Burden of Disease Study 2019, 62% of the deaths attributable to climate change were from CVD. Climate change mitigation is a slow, steady process, and the concept of co-benefits has arisen to promote climate action. This systematic review examines how numerous mitigation strategies, such as plant-based diets, increasing green spaces, increasing active transport, using renewable energy sources, and smoking cessation, may have the co-benefit of reducing CVD.

Methods

A mixed methods systematic review with narrative synthesis was conducted on four databases, according to the PRISMA guidelines. The articles retrieved (published between 2012 and 2022) had a mitigation strategy as the exposure, and CVD related morbidity or mortality reduction as an outcome.

Findings

The review found that renewable energy has a stronger association with cardiovascular co-benefits compared to emission reduction targets. Multimodal transport is more beneficial for both the climate and cardiac health than zero emission vehicles. Diet modification, such as Mediterranean and plant-based-diets, is positively associated with CVD reduction. Proximity to green spaces and reducing urbanisation may also improve cardiac health.

Interpretation

This systematic review demonstrates that implementing four mitigation strategies - increasing renewable energy use, active transport, green spaces, and plant-based diets; could lead to the co-benefit of reducing CVD morbidity and mortality. Furthermore, it illustrates the importance of plant-based diets and active transport to improve cardiovascular health.

Funding

This research received no specific grant from any funding agency in the public, commercial or not-for-profit sectors.

Pathways linking greenspace to behavioural problems in Polish children

Background

Previous cross-sectional studies have found a beneficial relationship between greenspace and children's behaviour. Nevertheless, evidence on the mechanisms underlying this association remains scant. We examined whether the availability of greenspace was related to fewer behavioural problems in Polish children and investigated potential mechanisms.

Methods

Data were obtained from the case-control NeuroSmog study, in which children with and without attention deficit hyperactivity disorder (ADHD) were tested from October 2020 to September 2022. The analytic sample comprised 679 children aged 10-13 years. Parents reported internalizing, externalizing, and total behavioural problems using the Child Behaviour Check List (CBCL), as well as information about the presence of a domestic garden and potential mediators: greenspace perception, neighbourhood social cohesion, and physical activity. Tree and grass covers were extracted in 500 m and 1 km buffers around lifelong residences. Structural equation modelling (SEM) was used to examine the psychosocial pathways linking the greenspace metrics to behavioural problems.

Results

Greenspace was only indirectly related to fewer behavioural problems. Specifically, tree cover was related to greater levels of physical activity which, in turn, was related to fewer internalizing and total behavioural problems. Tree cover and presence of garden were related to greenspace perception which, in turn, was associated with higher neighbourhood social cohesion which, in turn, was linked to fewer behavioural problems. The patterns of associations in children without ADHD were very similar to those in the full sample except that the associations from garden to greenspace perception and from physical activity to total behavioural problems were no longer significant. The only association persisted among girls was from neighbourhood social cohesion to behavioural problems and among boys were from tree cover to physical activity and tree cover and garden to greenspace perception.

Conclusion

Trees and garden, but not grass, are linked to fewer behavioural problems through greenspace perception, neighbourhood social cohesion, and physical activity in Polish children.

Greenspaces And Cardiovascular Health

Accumulating evidence suggests that living in areas of high surrounding greenness or even brief exposures to areas of high greenery is conducive to cardiovascular health, which may be related to the environmental, social, psychological, and physiological benefits of greenspaces. Recent data from multiple cross-sectional, longitudinal, and cohort studies suggest that living in areas of high surrounding greenness is associated with a lower risk of all-cause and cardiovascular mortality. High levels of neighborhood greenery have been linked also to a decrease in the burden of cardiovascular disease risk factors as reflected by lower rates of hypertension, dyslipidemia, and diabetes. Those who live in greener environments report better mental health and more frequent social interactions, which can benefit cardiovascular health as well. In this narrative review, we discuss evidence linking greenspaces to cardiovascular health as well as the potential mechanisms underlying the beneficial effects of greenspaces, including the impact of vegetation on air, noise and light pollution, ambient temperature, physical activity, mental health, and biodiversity. We review literature on the beneficial effects of acute and chronic exposure to nature on cardiovascular disease risk factors, inflammation and immune function, and we highlight the potential cardiovascular effects of biogenic volatile organic compounds that are emitted by trees and shrubs. We identify current knowledge gaps in this area and underscore the need for additional population studies to understand more clearly and precisely the link between greenness and health. Such understanding is urgently needed to fully redeem the promise of greenspaces in preventing adverse environmental exposures, mitigating the effects of climate change, and creating healthier living environments.

Show me the money! Associations between tree canopy and hospital costs in cities for cardiovascular disease events in a longitudinal cohort study of 110,134 participants

Health benefits from urban greening are assumed to translate into reduced healthcare expenditure, yet few studies have tested this. A total of 110,134 participants in the Sax Institute's 45 and Up Study in the Australian cities of Sydney, Newcastle, or Wollongong were linked with hospital cost data for cardiovascular disease (CVD) events (e.g., acute myocardial infarctions) up to 30 June 2018. Associations between percentages of total green space, tree canopy, and open grass within 1.6 km of participants homes and annual per person measured CVD-related hospital costs were analysed using generalised linear model (GLM) with gamma density as a component of a two-part mixture model, adjusting for confounders. Overall, 26,243 participants experienced a CVD-related hospitalisation. Incidence was lower among participants with 10 % more tree canopy (OR 0.98, 95 %CI 0.96, 0.99), but not with higher total green space or open grass percentages. Total costs of hospitalisations per year were lower with 10 % more tree canopy (means ratio 0.96, 95 %CI 0.95, 0.98), but also higher with 10 % more open grass (means ratio 1.04, 95 %CI 1.02, 1.06). It was estimated that raising tree canopy cover to 30 % or more for individuals with currently less than 10 % could lead to a within-sample annual saving per person of AU$ 193 overall and AU$ 569 for those who experienced one or more CVD-related hospital admissions. This projects to an estimated annual health sector cost reduction of AU$ 19.3 million per 100,000 individuals for whom local tree canopy cover is increased from less than 10 % to 30 % or higher. In conclusion, this longitudinal study is among the first to analyse measured healthcare cost data in relation to urban green space in general, and with differentiation between major types of greenery relevant to urban planning policies in cities around the world. In sum, this study advances an increasingly important and international focus of research by reporting on the lower burden of CVD and fewer associated hospitalisations stemming from upstream investments that protect and restore urban tree canopy, which not only translates into substantial reduced costs for the health sector, but also helps to create regenerative cities and flourishing communities.

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.