Evaluation of the Effectiveness of the Elderly Cognitive and Exercise Forest Therapy Program According to Brain Wave and Autonomic Nervous System Parameters

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This study compared improvements in physiologic functioning between two groups of older adults who underwent a 12-week forest therapy program. The manuscript maintains a good English, well-structured. However, I have the following doubts and questions about this manuscript that need to be clarified or addressed by the authors.

First, the experimental design of this study looks complete and the quantity of data is large, and there appears to be no timeliness issues with this study. Therefore, I do not understand why the authors chose to publish it in the form of a communication rather than an article.

Secondly, based on the above comment I would like to suggest the author to expand the background section as there is currently no adequate research background. For example, the severity of current (Korean) aging, the social significance and value of aging management. Furthermore, the strength of this study is not clear, the author states in lines 54-54 “However, there are not many studies that have verified the effect of performing a specific forest therapy program by checking multiple vital signs at the same time.” In fact, there have been many prior studies that have discussed the effect of performing a specific forest therapy by checking multiple vital signs at the same time.

Third, (Lines 71-73) the description of the purpose of this study is incorrect because this study used psychological scales in addition to biosignal parameters.

Fourth, the description of the methods section should be standardized, and the description of the environment of the experimental area is currently missing. Where is the forest therapy site? In what environment did the control group conduct the experiment?

Fifth, according to Table 1, there are significant differences in many variables between the two groups, such as age, weight, height, and some pre-test psychological scales (MMSE-K, EQ-5D, K-MoCA). How do the authors think that two groups with differences could be further compared?

Sixth, the process of forest therapy may need to be reassessed, as typically, forest therapy involves yoga, meditation, and walking in the forest. However, these subjects in the present study performed strength training and aerobic exercise, which could potentially impact the results of forest therapy, as the current authors' analytic process was unable to rule out the mediating role of high-intensity physical exercise leading to improvements in physiological function.

Seventh, despite the fact that COVID-19 is factual, it is recommended that the relevant discussion be removed (e.g., lines 185-188) because the study did not comparatively analyze these data, and the focus should be on the differences in experimental conditions between the control and experimental groups.

At the last, the discussion section only retraces the data results. More discussion of the methodology, innovations, and applied value of this study is needed, otherwise this will make this manuscript more of a project report.

Author Response

Thank you for your review comments on this manuscript. I think it helped a lot to improve the completeness of this manuscript by your review comment. I actively responded to the lack of content given by the reviewer and tried to apply it to the manuscript. Once again, thank you for reviewing this manuscript, and please check the following for responses to comments.

Comments 1: First, the experimental design of this study looks complete and the quantity of data is large, and there appears to be no timeliness issues with this study. Therefore, I do not understand why the authors chose to publish it in the form of a communication rather than an article.

Response 1: I agree with the your comments. The reason this article was not submitted as an article is that it does not meet the following conditions required for an article: "The work should report scientifically sound experiments and provide a substantial amount of new information." This study is more characteristic of being "part of a larger study over multiple years" rather than providing new information. Additionally, the page count is somewhat low. Based on your feedback, we will discuss this with the editor if the publication is confirmed. Thank you.

 

Comments 2: Secondly, based on the above comment I would like to suggest the author to expand the background section as there is currently no adequate research background. For example, the severity of current (Korean) aging, the social significance and value of aging management. Furthermore, the strength of this study is not clear, the author states in lines 54-54 “However, there are not many studies that have verified the effect of performing a specific forest therapy program by checking multiple vital signs at the same time.” In fact, there have been many prior studies that have discussed the effect of performing a specific forest therapy by checking multiple vital signs at the same time.

Response 2: Based on the feedback, the following content has been added to the background in the introduction of the study: “Currently, South Korea is experiencing serious issues of aging and low birth rates. As the elderly population increases, the age of the socially active population also rises, necessitating efforts to manage and maintain their health more stably. Medically, regular health check-ups are encouraged, and various hobby-based exercises are proposed for health management, with their benefits confirmed. However, considering the physical condition of the elderly, the choice of exercise types is limited. Additionally, the economic consumption for health management is increasing, putting a burden on household finances, thus raising the need for health management utilizing the surrounding environment. A representative example of this is forest therapy.” Furthermore, there are various prior studies that have confirmed the effects of forest therapy through biometric signals”.

 

Comments 3: Third, (Lines 71-73) the description of the purpose of this study is incorrect because this study used psychological scales in addition to biosignal parameters.

Response 3: I agree. EEG was used as a psychological scale, and PPG was used as a physiological signal measure. Therefore, the purpose of this study was analyzed using representative indicators that can confirm the purpose from two perspectives.

“The purpose of this study is to investigate changes in physical functions before and after participation in forest therapy programs using psychological scale parameters via EEG and autonomic nervous system parameters via PPG, comparing participants and non-participants. The study aims to identify significant variables to assess the effectiveness and impact of forest therapy programs composed of cognitive and exercise components.”

 

Comments 4 : Fourth, the description of the methods section should be standardized, and the description of the environment of the experimental area is currently missing. Where is the forest therapy site? In what environment did the control group conduct the experiment?

Response 4: All participants completed all measurements and surveys at the Cheongju Public Health Center before starting the program. The forest therapy was conducted in the Maebong-Mountain area of Cheongju, Chungcheongbuk-do. The control group was managed by the research team to ensure that all measurements were taken under the same conditions and timeframes(line 101-105).

 

Comments 5 : Fifth, according to Table 1, there are significant differences in many variables between the two groups, such as age, weight, height, and some pre-test psychological scales (MMSE-K, EQ-5D, K-MoCA). How do the authors think that two groups with differences could be further compared?

Response 5: I agree with your comments. Due to the differences in characteristics between the two groups, it cannot be considered that they were adequately controlled. Therefore, this study presents the differences before and after program implementation (or non-implementation) within each group, as shown in Tables 4 and 5, rather than between-group analysis. We acknowledge that proper control is necessary to confirm the effects of forest therapy, and this is mentioned in the limitations section of the study. Future research will aim to recruit and manage participants with tighter controls to directly confirm the effects of forest therapy. We appreciate your understanding.

 

Comments 6: Sixth, the process of forest therapy may need to be reassessed, as typically, forest therapy involves yoga, meditation, and walking in the forest. However, these subjects in the present study performed strength training and aerobic exercise, which could potentially impact the results of forest therapy, as the current authors' analytic process was unable to rule out the mediating role of high-intensity physical exercise leading to improvements in physiological function.

Response 6: I agree with your comments. But, the strength and aerobic exercises mentioned in the forest therapy program of this study are not typical exercises. In the case of strength training, it includes preparatory gymnastics and fine motor exercise programs such as hand pressing, shoulder rotation, tapping, etc., as well as aerobic exercises with knee and arm movements and loud breathing. These are not high-intensity physical exercises but are at a similar level to general yoga, meditation, and walking in the forest. We have revised the program content in Table 3 to avoid any misunderstandings.

 

Comments 7 : Seventh, despite the fact that COVID-19 is factual, it is recommended that the relevant discussion be removed (e.g., lines 185-188) because the study did not comparatively analyze these data, and the focus should be on the differences in experimental conditions between the control and experimental groups.

Response 7 : I agree with your opinion. Lines 185-188 have been deleted. Thank you.

 

Comments 8 : At the last, the discussion section only retraces the data results. More discussion of the methodology, innovations, and applied value of this study is needed, otherwise this will make this manuscript more of a project report.

Response 8 : To address the discussion of reporting results in a report format and to summarize the positive impacts of forest therapy, I have compiled the following content. It is important to note that our study did not directly control for specific positive factors or influences emitted in actual forest therapy environments, hence we integrated indirect changes in cognition and physiological functions.

Forest therapy has shown to have numerous positive effects on both mental and physical well-being. Activities and relaxation in forest settings have been associated with reductions in blood pressure, improvements in cardiovascular function, and decreases in stress-related hormones like cortisol, as evidenced by previous research. Additionally, engagement with forest environments has been linked to enhancements in cognitive function, likely due to the calming and rejuvenating qualities of natural surroundings.

Our study contributes to this understanding by observing trends such as a reduction in left-right brain asymmetry among participants in the forest therapy program. This highlights the indirect yet significant impacts of forest environments on cognitive and physiological responses. It is essential to acknowledge that while our study did not directly manipulate specific environmental elements, our findings are consistent with existing literature that emphasizes the comprehensive benefits of forest therapy. This indirect approach allows us to appreciate the broader implications of engaging with natural environments for therapeutic purposes. I hope this clarifies how we approached discussing the positive influences of forest therapy in our study.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

This is a unique paper about changes in various physiological functions due to forest therapy.

However, although it is a research paper on forest therapy, that is, therapy in a forest environment, it completely lacks any description of the forest environment (tree species, density, tree height, DBH, vegetation, color, and so far). This means that the foundation and core of this research, which focuses on the forest environment, is fundamentally missing.

Therefore, due to this fundamental and major deficiency as a research paper, it has been determined that it should be rejected.

Author Response

Thank you for your review comments on this manuscript. You have raised concerns about the suitability of this manuscript for publication in this journal. While I agree with some of your points, upon reviewing the objectives of this special issue and considering other papers published in this journal, I have some differing thoughts. Please review the following comments and opinions.

 

Comments 1: This is a unique paper about changes in various physiological functions due to forest therapy.

However, although it is a research paper on forest therapy, that is, therapy in a forest environment, it completely lacks any description of the forest environment (tree species, density, tree height, DBH, vegetation, color, and so far). This means that the foundation and core of this research, which focuses on the forest environment, is fundamentally missing.

Therefore, due to this fundamental and major deficiency as a research paper, it has been determined that it should be rejected.

Response 1: This special issue explores aspects of forest therapy that utilize cognitive neuroscience, smart devices, and wearable devices to assess their effectiveness. Therefore, this study aimed to explore changes in physiological functions in forest therapy.

I agree with your opinion. It is important to note that our study did not directly control for specific positive factors or influences emitted in actual forest therapy environments, hence we integrated indirect changes in cognition and physiological functions. Forest therapy has shown to have numerous positive effects on both mental and physical well-being. Activities and relaxation in forest settings have been associated with reductions in blood pressure, improvements in cardiovascular function, and decreases in stress-related hormones like cortisol, as evidenced by previous research. Additionally, engagement with forest environments has been linked to enhancements in cognitive function, likely due to the calming and rejuvenating qualities of natural surroundings. Our study contributes to this understanding by observing trends such as a reduction in left-right brain asymmetry among participants in the forest therapy program. This highlights the indirect yet significant impacts of forest environments on cognitive and physiological responses.

It is essential to acknowledge that while our study did not directly manipulate specific environmental elements, our findings are consistent with existing literature that emphasizes the comprehensive benefits of forest therapy. This indirect approach allows us to appreciate the broader implications of engaging with natural environments for therapeutic purposes. I hope this clarifies how we approached discussing the positive influences of forest therapy in our study

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

My comments to the authors are on the manuscript that I have uploaded.

Comments for author File: Comments.pdf

Comments on the Quality of English Language

Author Response

Thank you for your review comments on this manuscript. I think it helped a lot to improve the completeness of this manuscript by your review comment. I actively responded to the lack of content given by the reviewer and tried to apply it to the manuscript. Once again, thank you for reviewing this manuscript, and please check the following for responses to comments.

 

Comments 1: Line 52, “Qualitative methods “should be “Qualitative and quantitative methods…” Data from surveys and blood sampling are considered quantitative, if all are numerical and analyzed using parametric methods.

Response 1: I agree with your suggestion. According to your feedback, I have revised it to "qualitative and quantitative methods" in line 59. Thank you.

 

Comments 2: Line 63, the time between pulses do not measure blood volume. For example, you can have a slow heart rate with a longer time between pulses and poor blood volume that leads to syncope. You can have a high heart rate with shorter time between pulses and good blood volume and heart failure occurs. Please correct.

Response 2: I agree with your suggestion. I have removed "blood volume pulse (BVP)," which could potentially cause misunderstanding. Thank you for your feedback.

 

Comments 3: delete "were divided".

Response 3: I have removed "were divided". after 25~. Thank you for your feedback.

 

 

Comments 4 : There is evidence of significant baseline differences between groups. Must be controlled in analysis.

Response 4 : I agree with your comments. Due to the differences in characteristics between the two groups, it cannot be considered that they were adequately controlled. Therefore, this study presents the differences before and after program implementation (or non-implementation) within each group, as shown in Tables 4 and 5, rather than between-group analysis. We acknowledge that proper control is necessary to confirm the effects of forest therapy, and this is mentioned in the limitations section of the study. Future research will aim to recruit and manage participants with tighter controls to directly confirm the effects of forest therapy. We appreciate your understanding.

 

Comments 5 : This paragraph seems to be written in a non-logical order. Please review and cluster all EEG information together and then the HRV information separately.

Response 5 : I agree with your opinion. I have separated the EEG and PPG sections into 2.2.1 and 2.2.2, respectively.

 

Comments 6: More discussion of the meaning of these variable will support your results presentation and your discussion interpretation.

Response 6: I agree with your comments. In Table 2, the described variables were supplemented in the discussion with physiological and medical definitions to support the interpretation of the results. Thank you for your feedback.

 

Comments 7 : "Program group," do you mean experimental group, please explain or change. This is confusing as written.

Response 7 : I agree with your opinion. I have corrected " Program group" to "experimental group". Thank you.

 

Comments 8 : You have inferred quite a bit in the discussion of your findings. Relatively, your significant findings did not span a variety of measures and these inferences are a big leap interpretation. Please consider revision.

Response 8 : I have deleted the statement: "Therefore, it can be interpreted that the program's influence leads to a higher level of activation of the sympathetic nervous system, which in turn indicates an increased response to stress." This was removed as it could potentially lead to overinterpretation, particularly regarding stress levels not directly measured. Thank you for your feedback.

 

Comments 9 : See note in methods section on these variables. These variables were not written in detail in the methods so that the discussion here can be understood well.

Response 9 : I have specified "functional vasodilation capacity" for Tad below. I believe the discussion has been supplemented with the methods of calculation and physiological definitions for Tad and Tae as follows: "which means functional vasodilation capacity, and in general, for elderly people who did not participate in the program, the increase in Tad means that the time decreases until the residual amount remains after the blood flows."

 

Comments 10 : Limitations: the study design was weakened by not conducting pre-/post measures of the variables directly before and after one session. For example, in your next study will you do a pre/post on several of the sessions? Such as, the first session, after 4, 8 and 12 sessions. This might have helped with the COVID-19 break as well as understanding the effect of each session for park/forest/exercise prescription.

Response 10 : I agree with the limitations of this study. Thank you for your valuable feedback. Accordingly, I have added the following statement: "We will conduct pre/post measurements at several sessions, such as after the first session, and then after the 4th, 8th, and 12th sessions."

 

Comments 11 : This study was really a feasibility study with hypothesis generation on imbalanced differences between EG and CG. The findings were limited and large leaps in interferences were made.

Response 11 : I agree with the limitations of this study. Thank you for your valuable feedback. We will strive to produce results under more controlled conditions in future research. Your understanding is appreciated.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

I appreciate the author's consideration and response to my comment. However I still have the following comments:

1) For the type of article, I would suggest that the authors consider it carefully;

2) I suggest that the authors should add a zone map of the experimental area and site;

3) According to iThenticate's originality check, the repetitiveness of this manuscript is too high (22%), and this generally needs to be reduced to less than 15%.

Author Response

Thank you again for your review opinion. We have prepared a response to the additional opinions provided below, and have made revisions taking all of your opinions into consideration. Thank you again for your review.

Point 1: 1) For the type of article, I would suggest that the authors consider it carefully;

Response 1: I respect your opinion. I will discuss this with the editor and make sure to reflect the change to an “Article”. Thank you.

 

Point 2: 2) I suggest that the authors should add a zone map of the experimental area and site;

Response 2: Following your suggestion, I have added the zone map as Figure 1. Thank you.

 

Point 3: 3) According to iThenticate's originality check, the repetitiveness of this manuscript is too high (22%), and this generally needs to be reduced to less than 15%.

Response 3: I believe that the high similarity in measuring and analyzing biosignals in forest therapy may be due to the methodological similarities in this field. Many papers have already been published, which could explain the 22% similarity index. Specifically, the methods of analyzing EEG and PPG are mostly standardized, making it challenging to modify them. However, the results are recorded differently depending on the characteristics of the forest therapy program and the participants. Adjusting the content to keep the similarity below 15% would be difficult. I hope you understand these considerations. Thank you.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

This revised manuscript has been added some points. 

Author Response

Thank you again for your review opinion..

Point 1: This revised manuscript has been added some points. 

Response 1: Thank you for taking the time to review this manuscript. I will strive to conduct better research and write improved papers. Thank you.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

This manuscript is greatly improved. In the discussion there is a section that needs to have citations added:

Previous studies have confirmed that forest environments are linked to reduced levels of the stress hormone cortisol (Cite here). Additionally, activities in forests can influence cognitive function (Cite here). As seen in the results of our study, there was a higher tendency for reduction in left-right brain asymmetry in the group participating in the program. Thus, the reasons for engaging in forest therapy indirectly confirm the various positive impacts provided by diverse forest environments (Cite here).

Author Response

Thank you again for your review opinion. We have prepared a response to the additional opinions provided below, and have made revisions taking all of your opinions into consideration. Thank you again for your review.

Point 1: This manuscript is greatly improved. In the discussion there is a section that needs to have citations added:

Previous studies have confirmed that forest environments are linked to reduced levels of the stress hormone cortisol (Cite here). Additionally, activities in forests can influence cognitive function (Cite here). As seen in the results of our study, there was a higher tendency for reduction in left-right brain asymmetry in the group participating in the program. Thus, the reasons for engaging in forest therapy indirectly confirm the various positive impacts provided by diverse forest environments (Cite here).

 

Response 1: I have supplemented the references you suggested adding. Thank you once again for your review.

1) ~ hormone cortisol …

[31. Kobayashi, H.; Song, C.; Ikei, H.; Park, B.-J.; Lee, J.; Kagawa, T.; Miyazaki, Y. Population-Based Study on the Effect of a Forest Environment on Salivary Cortisol Concentration. Int. J. Environ. Res. Public Health 2017, 14, 931. https://doi.org/10.3390/ijerph14080931]

2) ~cognitive function …

[32. Berman, M.G.; Jonides, J.; Kaplan, S. The cognitive benefits of interacting with nature. Psychol. Sci. 2008, 19, 1207–1212. https://doi.org/10.1111/j.1467-9280.2008.02225.]

[33. Kim, J.G.; Jeon, J.; Shin, W.S. The Influence of Forest Activities in a University Campus Forest on Student’s Psychological Effects. Int. J. Environ. Res. Public Health 2021, 18, 2457. https://doi.org/10.3390/ijerph18052457]

3) ~ forest environments …

[34. Mazzoleni, E.; Donelli, D.; Zabini, F.; Meneguzzo, F.; Antonelli, M. Forest Therapy Research in Europe: A Scoping Review of the Scientific Literature. Forests 2024, 15, 848. https://doi.org/10.3390/f15050848]

Author Response File: Author Response.pdf