The Moderating Effect of Social Participation on the Relationship between Urban Green Space and the Mental Health of Older Adults: A Case Study in China

Round 1

Reviewer 1 Report (New Reviewer)

This is an interesting paper with potentially useful insights for policy and practice. It is generally well-written and appropriately described.

I cannot comment on the robustness of the statistical analysis in detail; in particular I am not familiar with Johnson-Neyman plotting, although it appears useful and appropriate in this paper. I recommend than another reviewer with appropriate expertise reviews this.

The key finding, i.e. that social participation weakens the positive influence of green spaces on solitary-living older adults’ mental health (the converse of the finding for non-solitary older adults), at first appears counter-intuitive. The proposed explanation by the authors makes sense, i.e. that social participation is especially desirable for solitary older people and therefore is likely to dominate any positive effect of visiting a particular environment, including green space. But it might have been expected that the attraction of green space enjoyment would be enhanced further by having social interaction associated with it. Can the authors perhaps comment further on this? For example, is it possible that green space is valued by solitary people for what it offers other than social interaction, as such people are more likely to visit alone and therefore are attracted by, e.g. the contact with nature and its psychological benefits, rather than green space as an opportunity to meet people. By comparison, people living with others may be more likely to visit green spaces in a socially interactive context anyway and therefore expect their experience to be enjoyed with others and like it to be so.

It would be good to see just a little more reflection on this from the authors. I think this might also help inform the conclusions better. For example, at present the findings do not really justify the statement in lines 704-706 that the government should be “providing high-quality urban green space to carry out social activities for the solitary older adults”, but rather that solitary adults need support for social contact and social activities that are not reliant on green space contexts, while for non-solitary adults, social activities in green space should be encouraged and supported.

My detailed comments are not major but I include them below to help the authors optimise the clarity and usefulness of the paper.

Lines 15-16 and 79-80 – “most studies analyse urban green space as an indicator of built environmental factors” – it’s not clear exactly what is meant by this statement – “indicator” of what in relation to built environment? Indicator of quality of the built environment? If so, that would seem incorrect as studies have considered a range of indicators of urban deprivation, including vandalism, derelict sites, housing quality, population density and crowding, etc.. If this is not what is meant, then it’s unclear what the point being made is.

Lines 42-44 “ Urban green space is a scarce resource that can improve mental health by promoting social interaction and physical activity, thereby alleviating the negative impact of the ‘urban disease’”. As an introduction to the links between urban green space and mental health, this is too limited, as other mechanisms have been identified (including psychophysiological effects, pollution moderation, influences on the microbial-gut-brain axis, attention restoration, etc) in the literature for some time. It seems appropriate to acknowledge these in introducing what is already known about urban green space and health links.

Figure 1 – It’s not clear what the ‘greening rate’ and ‘urbanisation rate’ refer to here. Later in the paper (lines 255-267) suggest that ‘greening rate’ is not about rate of change but about the proportion (?) of urban green space in the city. However, it is not clear what the urbanisation rate refers to – is this the proportion of urban area covered by buildings, rather than a rate of change? How does it differ from population density? Use of clearer and more accurate terms would help.

Lines 156-7 – “Previous studies have shown that green spaces have multiple roles in improving the mental health of older adults”. The authors need to be careful to distinguish between studies that show an association between green spaces and mental health and studies that show how green spaces can be used to improve mental health over time. The latter are much more challenging and most studies fall into the former category. Similar care needs to be taken in commenting on research linking social participation and mental health. And in discussing the effects of older people living with or near their children (see lines 211-2).

Lines 243-252 – this paragraph needs more justification for the cut-off ages chosen for men and women. If women generally live longer than men, why is an older woman someone aged 60 and over, while for men it is those aged 65 and older? One might expect the opposite to be more logical. The English in this paragraph is also poor and ungrammatical in a number of places and needs correcting.

Section 3.2.1 – lines 292-6 list the key variables used in the linear regression model but doesn’t explain that the details are given in section 3.3.1-3.3.3 below. It would be helpful to signal this to the reader at the start of this section.

Section 3.3.1 – Depression is only one dimension of mental health. It would be useful for the authors to justify why they’ve chosen this measure as opposed to others (e.g. life satisfaction, positive affect, anxiety) to indicate mental health. If the focus of the paper is actually on depression, specifically, it would be better to adjust the title of the paper accordingly.

Line 359 – how is the ‘urbanisation rate’ defined? It’s not immediately clear and I suspect this is a measure of land use cover, not related to rate of change (see earlier comment on Figure 1).

Lines 526-7 “Our results showed that excessive alcohol consumption leads to depressive symptoms and mental health problems.” Do they? Surely the results simply show an association between the two and a reverse causal direction is possible, i.e. that more depressed older people turn to alcohol in an attempt to alleviate their mental ill-health?

Lines 555-558 – the same sentence is repeated in these lines.

Lines 558-559 – Another  possible explanation for the lack of an effect of hospitalisation on solitary older adults’ depression may be that hospitalisation involves a level of social and care contact with others that may be welcome for someone otherwise managing health problems on their own.

Line 611 – “tend to focus on their mental health” seems incorrect language here.

Lines 624-626 “Previous studies used social interaction as an intermediary variable to explore the impact of green space on mental health [35], whereas the role of social interaction has been overlooked.” This sentence seems to negate itself. What do the authors mean?

The quality of English is generally good but it does still need a final check and is poor in some places. I have just picked out a few examples below.

Lines 77-78 – English needs checking. “Research on urban green space and the mental health of older adults is gradually becoming increasing” is not grammatically correct.

Lines 186-9 – “This [continuity] theory highlights individuals’ autonomy and moderate frequency rather than striving for increases” – it is not clear what this means.

Lines 271-2 “Among those characteristics”. What is this referring to?

Line 335 “In addition” is inappropriate here.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report (New Reviewer)

The study aims to investigate the impact of urban green space on the mental health of older adults in China, with a focus on the aging population. It employs linear regression models and a moderating effect analysis to analyze the 2018 China Labor Dynamics Survey data.

The introduction provides a clear context for the study by highlighting the increasing proportion of China's elderly population and the environmental and social challenges they face. However, it could be strengthened by including a brief overview of existing literature on the relationship between urban green space, social participation, and mental health in older adults.

The objectives of the study are well-defined, focusing on analyzing the moderating effect of social participation on the relationship between urban green space and mental health. Identifying research gaps regarding the influencing mechanisms and the role of sociality in the impact of green space on mental health is valuable.

The methodology section provides a clear overview of the research design, variables, and measures used. However, it would benefit from further elaboration on the specific statistical techniques employed for the linear regression models and moderating effect analysis.

The results section presents a comprehensive overview of the findings, including the significant effects of various factors on mental health in older adults.

The discussion section adequately summarizes the main findings and highlights the importance of addressing environmental and social factors in urban environments to promote the mental health of older adults. However, it could further explore the underlying mechanisms that explain the differential impact of social participation on solitary and non-solitary older adults.

The conclusion provides a concise summary of the study's findings. However, it could be strengthened by emphasizing the practical implications of the research and suggesting more specific recommendations for policymakers and urban planners.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report (New Reviewer)

The topic of the article is very popular, even fashionable. A lot of research and publications are devoted to it.

Similar research can be found in other times, e.g. in the article:

Exploring the relationship-oriented spaces of social networks and depressive symptoms among older adults

https://www.sciencedirect.com/science/article/pii/S2095263523000948

https://www.sciencedirect.com/science/article/pii/S2095263523000948?via%3Dihub

The topic is up to date and necessary from the point of view of the quality of life.

Aging friendly cities, Social participation, Greenery are frequent research topics.

The results presented in the article are not surprising, rather they confirm several partly intuitive findings. The overall methodological procedure seems to be in order. The benefit is finely tuned methodology. Although there are too many hypotheses in the article for one study, one and complementary research questions would be sufficient.

 I evaluate the article from the point of view of urban planning and public space architecture. I leave the relevance of statistical procedures to a better expert.

The formulation of the limits of the research and the indicated continuation in the scale of the human horizon and the direct impact of the sensory perception of urban vegetation are essential.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.

Round 1

Reviewer 1 Report

This paper is a scholarly essay investigating the influence of urban green spaces on the mental well-being of elderly individuals in China.   The analysis examined data from the 2018 China Labor Dynamics Survey, including a sample of 3,501 elderly individuals residing in 146 urban areas.   The researchers used linear regression models and performed a moderating effect study to investigate the correlation between urban green space, social involvement, and mental health. The research findings indicated that urban green spaces, together with variables such as road density, physical condition, hospitalization, personal subjective well-being, and economic contentment, had a substantial impact on the mental well-being of older individuals.   Green space and mental health in older individuals were shown to be impacted differently by social activity, indicating a moderating effect. The research also compared older individuals who live alone and those who do not, revealing disparities in the factors that affect their mental well-being.   The study's results enhance comprehension of the influence of urban green spaces on the mental well-being of elderly individuals and may aid in creating age-friendly cities in China.   The research proposes that by improving urban development and applying techniques to create healthy surroundings, the mental well-being of older individuals may be enhanced.

Please mention the gaps in research studying the relationship between using urban spaces and mental health among the elderly. Which gaps do the authors fill in their study?

Please highlight the aim of your study in the introduction.

Please explain why the authors know the variable of social participation as the moderator and not the mediator in their study.

Please complete the research framework with all variables in Fig.2.

Please mention the population density in different study areas.

Please rearrange and rewrite the paper according to the structure of a scientific paper as discussion and conclusion .

Please explain: What is the role of social involvement in influencing the connection between urban green space and the mental well-being of older individuals?

A native editor can improve the quality of writing.

Reviewer 2 Report

Overall:

This study aimed to assess the association between urban green spaces and mental health among elderly. In general, the topic is interesting, but the manuscript lacks important information related to the methodology. This section should be improved and supplemented.

Materials and Methods:

·         Why were men from 65 and women from 60 included in the study? Why the different ages?

·         It should be described in more detail how greenness was assessed? Was it assigned to each person separately according to their place of residence?

·         It should be indicated how solitary and non-solitary people were distinguished.

·         Illness among older people was measured based on whether they had an illness in the past two weeks. But what about chronic diseases that directly affect mental health?

·         How was PM2.5 data obtained and assigned to each participant?

·         Have you assessed the accessibility to greenness or the nearest park and the use of green space?

·         It should be explained what Hukou status is.

·         Did you have income information? This factor is also associated with mental health.

Results:

·         Table 4 shows the results of the independent sample test; however, it is not specified which variable mean values and differences are presented.

·         When calculating regression analysis, confidence intervals and R² should be presented.

Discussion

·         Discussion should be supplemented with more practical implication of the study results.

Minor errors:

·         Line 482: The numbers indicate that it is not correlation coefficients.

Minor editing of English language required.

Reviewer 3 Report

Thank you for allowing me to review your paper. I found the topic interesting but there were a number of areas for improvement. Please find my detailed feedback below:

Title:

·       * This study seems to be specific to China so I would have this in the title as it isn’t global.

Abstract:

·       * There is some green space and wellbeing data focused on older adults out there so I think your 2^nd sentence needs to be modified slightly to “however, often they have ignored the internal mechanism of the effect of urban green space on the mental health of older people”

·      *  I would delete the 3^rd sentence because ~3,500 sample from 146 cities isn’t going to tell you the exact interrelation.

·       * Also just be careful with the overuse of words like "therefore". There are two sentences back-to-back that use it and it’s jarring.

·      *  I am not a quantitative researcher but this seemed to be cross section. Please specify.

·       * I am unclear why factors such a road density are linked to green spaces. This seems random can it be clarified why these factors were looked at.

·      * The social element from your abstract seems to be the most important factor not green spaces. Can you explain how green spaces impact health as this is in your title and intro and abstract and their not clear.

Introduction.

·       * At the start I am unclear what aging and elderly is classified as. Please specify this.

·       * Also the first 2 sentences need references. You cannot just summarise documents. Obviously you got these numbers from somewhere.

·      *  Just be careful with language usage. Previously it is third person and in the 3^rd sentence you use “our” to describe China so it flips tenses. Pay special attention to this language.

·       * The citation 3 is about living alone and not about aging so the assertion made should be tempered.

·       * The sentence starting a “A large number of…” changes ideas and therefore there should be a paragraph split or effort should be made to make stronger linking sentences. This speaks to the whole paper in that it needs a really good copy edit before re-submission. Right now the jumping of ideas makes the flow hard to follow.

·        * I am surprised that there is no reference to the work of Professor Thomas Astell-Burt who has done some really groundbreaking work in this field. Please check out some of it here: https://scholars.uow.edu.au/thomas-astell-burt/publications

·       * Also there are activities in green spaces such as gardening where there is evidence of the mental health benefits to older people and this isn’t event acknowledged. Here is a example of such research: https://www.sciencedirect.com/science/article/pii/S0272494423000415. Such studies are important to refer to in section 2.3 and there are a number of them not mentioned. 

·       * I am not sure the detail of section 2.1 is required – maybe they could be relevant in your methods if you are using the scale you can mention it.

·       * Section 2.2. needs a clearer link – originally you talk about green spaces and then built environments. These are different concepts and the link needs to be clearer.

·       * Section 2.3 socio-economic composition, social capital and social cohesion are very complex concepts but they are glossed over. I wouldn’t mention them unless you are mentioning them in-depth as theories like social capital are complex and cannot be glossed over. This will depend on the data you collected too.

·       * Overall I think the Introduction and literature review are too long and need to be tightened.

Method and results

·       * I am predominantly a qualitative research but I really struggled to follow the key points/findings from this study. Can you simplify and not chuck in too many tables and figures to make it easier to follow the key findings from this study. I think you need to be selective with the key findings and put the other data in supplementary materials and somehow highlight the key points.

Conclusion and discussion.

·       I am confused why the conclusion comes before the discussion. Please see the formatting of normal papers. The conclusion should not just be a summary but extending the research field. And the discussion should be comparing and contrasting findings with literature and how your research extends it. Also the limitations shouldn’t be the final thing of the paper. It should probably be a sub heading between discussion and conclusion.

I have commented on this above but I think the structure and flow (for example linking sentences) need to be worked on so the reader can more easily follow your key messages. A thorough copy edit is needed.