The Effects of Mindfulness Techniques on Anxiety, Depression, and Stress, with an Emphasis on Gratitude: A Systematic Review and Meta-Analysis

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This systematic review addresses a timely and highly relevant topic, as anxiety, depression, and stress continue to pose major global public health challenges. The manuscript provides a comprehensive synthesis of evidence on the effectiveness of mindfulness-based interventions, with a novel and well-justified emphasis on gratitude-based components. The inclusion of a large number of studies and participants strengthens the review, and the focus on randomized controlled trials and quasi-experimental designs enhances the credibility of the findings.

The abstract is generally clear and well structured, and the reporting of pooled effect sizes and subgroup analyses adds scientific value. However, several points could be improved to enhance clarity and methodological transparency. First, it would be helpful to briefly clarify whether a formal meta-analysis was conducted, as the reporting of a pooled Hedges’ g suggests quantitative synthesis, which should be explicitly stated. Additionally, more detail on the criteria used to assess risk of bias and publication bias would improve interpretability. The term “gratitude-integrated MBIs” should be defined more precisely to ensure consistency across included studies. Some minor language refinements are also recommended, such as avoiding repetition and slightly tightening the phrasing in the conclusions to prevent overgeneralization, given the heterogeneity of populations and intervention formats.

Overall, this review offers a valuable contribution to the literature on non-pharmacological mental health interventions. With minor clarifications regarding methodology and terminology, the manuscript would be suitable for publication in a healthcare or mental health–focused journal.

Author Response

We sincerely thank you for your time and valuable comments, which have helped us improve the quality and clarity of our manuscript. In the revised version, all modifications made in the manuscript are highlighted in yellow.

We have explicitly stated that a formal random-effects meta-analysis was conducted in both the Abstract and the Statistical Analysis section to ensure full methodological transparency.

We have expanded the description of risk of bias and publication bias assessment by explicitly stating the tools, domains, and interpretative criteria used, and aligned the discussion with the statistical results.

We have provided an explicit operational definition of “gratitude-integrated MBIs” in the Methods section to ensure conceptual consistency across included studies.

We have refined the language in the Conclusions section to reduce repetition and avoid overgeneralization, explicitly acknowledging population and intervention heterogeneity.

Reviewer 2 Report

Comments and Suggestions for Authors

Please find the comments:

1. If is a systematic review prepared according to PRISMA guidelines, it is unclear why the title does not include the information that this is a systematic review. I would recommend the authors to check all the PRISMA guidelines and provide a PRISMA 2020 expanded checklist. It is unclear why the authors included the exact text from the paper in their PRISMA checklist (it is uncommon practice, lines referring to the information should be included instead). https://www.prisma-statement.org/prisma-2020-checklist
2. Adding more keywords (up to ten) would be beneficial. 
3. It is unclear why Scopus and Web of Science databased were not searched.
4. Exclusion criteria should be indicated.
5. Lines 117: "Studies published within the last 10 years were prioritized." What does this mean in terms of methodology? Were older studies excluded? Please provide specific details on methodology rather than somewhat vague phrases.
6. Please provide specific details on "A comprehensive search was performed using the Elicit platform. Relevant keywords and Boolean operators were applied to optimize retrieval, including combinations of terms such as “mindfulness,” “gratitude,” “stress,” “depression,” “anxiety,” and “mental health.”". Were these exact keywords? Which Boolen operator were used? 
7. "The first 500 most relevant articles were retrieved and screened by two authors independently for eligibility based on predefined inclusion criteria. ". What does this mean that the first 500 most relevant articles were retrieved? Did you receive more articles but analyzed only the first 500? It is unclear based on the language used in the paper.
8. Many details on methodology are missing. I recommend strictly following the PRISMA guidelines to explain each methodological point. For instance, how was the data analyzed? By whom? How were discrepancies handled by the authors? What was the code for AI tools to extract data (please present in the Supplementary Materials for transparency reasons). Etc. Please see the PRISMA expanded checklist to find missing methodological elements in the study.
9. It would be beneficial to discuss the methodological limitations of the included studies and consider how these can impact the effectiveness of interventions.
10. While the authors demonstrated the limits of the included studies, the limitations of the review procedure of their own study should be demonstrated.

Author Response

We thank you for your valuable comments, which have helped us improve the quality and clarity of our manuscript. In the revised version, all modifications made in the manuscript are highlighted in pink.

1. We agree with the reviewer and have revised the title to explicitly identify the manuscript as a systematic review, and we have replaced the PRISMA checklist text with section and line references in accordance with PRISMA 2020 recommendations.
2. The list of keywords has been expanded to include additional relevant terms in order to improve the indexing and discoverability of the manuscript.
3. Scopus and Web of Science were not searched because the literature retrieval was conducted using the Elicit platform, which aggregates and indexes records from multiple major bibliographic sources, including PubMed, Semantic Scholar, and journals indexed in Scopus and Web of Science.
4. We have explicitly added the exclusion criteria in the Methods section to clarify the study selection process and improve methodological transparency.
5. We agree that the original wording was insufficiently precise. We have revised the Methods section to clarify that no formal publication date restriction was applied; studies published within the last 10 years were prioritized to reflect contemporary practices, while older studies were included if they met all eligibility criteria.
6. We have revised the Search Strategy section to specify the exact keywords and Boolean operators used, and to clarify how the Elicit platform expanded search terms to retrieve relevant records.
7. We agree that the original wording was unclear. We have revised the Methods section to clarify that the search returned 500 records in total and that all retrieved records were screened independently by two authors, rather than selecting only a subset.
8. We have explained the Methods section to clarify reviewer roles, data analysis procedures, discrepancy resolution, and the supervised use of AI tools. Additional methodological details and AI transparency information have been provided in the Supplementary Materials, in accordance with PRISMA 2020 expanded guidelines.
9. We have added in the Discussion to explicitly address the methodological limitations of the included studies and to explain how these factors may influence the magnitude and consistency of intervention effects.
10. We have added a dedicated paragraph discussing the methodological limitations of the review process itself, including search strategy constraints, potential selection bias, and heterogeneity-related limitations.

Reviewer 3 Report

Comments and Suggestions for Authors

The manuscript presents a well-executed systematic review and meta-analysis on mindfulness-based interventions, with a valuable emphasis on gratitude-focused practices. The study is methodologically sound, follows PRISMA guidelines, and addresses a topic of high relevance to mental health research and practice. The following minor revisions are suggested to further enhance clarity, interpretability, and accessibility for a broad readership.

1. Clarification in the Results Section
   While the statistical reporting is appropriate, the Results section would benefit from brief interpretive statements following key effect size estimates (e.g., Hedges’ g). Adding one sentence explaining the practical or clinical meaning of these effect sizes (e.g., small, moderate, or meaningful symptom reduction) would improve readability without altering the analyses.

2. Figure Caption Enhancement
   The forest plots are clear and correctly presented; however, figure captions could be expanded slightly to guide readers. Please consider indicating the direction of effects and clarifying what negative versus positive effect sizes represent in relation to symptom reduction.

3. Improvement of Table Readability
   Some tables summarizing study characteristics are information-dense. Readability could be improved by adding internal subheadings (e.g., intervention type, duration, primary outcomes) or by separating population characteristics and intervention characteristics into distinct sections, while retaining all reported data.

4. Brief Interpretation of Heterogeneity
   Heterogeneity statistics are appropriately reported. A short explanatory note discussing potential sources of heterogeneity—such as differences in study populations, intervention duration, or delivery mode (in-person vs. digital)—would strengthen the Results or Discussion sections.

5. Clearer Distinction of Gratitude Components
   The discussion of gratitude-based practices is a strength of the manuscript. To enhance conceptual clarity, please explicitly state whether gratitude was implemented as a core intervention component or as an adjunct to mindfulness, and briefly discuss how this distinction may influence interpretation of the observed effects.

6. Expansion of the Limitations Section
   The limitations are adequately acknowledged. Consider adding one sentence noting that variability in the operationalization of gratitude practices across studies may have contributed to outcome heterogeneity and that publication bias detection methods may have limited sensitivity.

7. Minor Language and Style Refinement
   The overall quality of English is good. Minor stylistic refinements—such as breaking up a few long or complex sentences in the Results and Discussion—would further improve clarity.

Overall, these are minor, primarily editorial and interpretive revisions that do not affect the scientific validity of the study. Addressing them will enhance the manuscript’s clarity and impact.

Author Response

We thank you for your valuable comments, which have helped us improve the quality and clarity of our manuscript. In the revised version, all modifications made in the manuscript are highlighted in green.

1. We have added brief interpretive statements following the key effect size estimates in the Results section, explicitly indicating the practical and clinical relevance of the reported Hedges’ g values (e.g., small to moderate symptom reduction). These additions improve clarity and readability without altering the statistical analyses.
2. The figure captions of all forest plots have been expanded to explicitly indicate the direction of effects and to clarify the interpretation of negative versus positive effect sizes in relation to symptom reduction. These additions improve interpretability while leaving the figures and analyses unchanged.
3. We carefully reviewed the structure of the tables summarizing study characteristics. Given the heterogeneity of the included studies and the need for a direct, side-by-side comparison across multiple variables, we opted to retain the current table format, which was intentionally designed to be comprehensive and serve as a detailed reference for readers. We believe that reorganizing the tables into separate sections or tables could fragment the information and reduce comparability. Nevertheless, we ensured that the tables are clearly labeled and consistently structured to support readability.
4. A brief explanatory note discussing potential sources of heterogeneity (including differences in study populations, intervention duration, and delivery mode) has now been added to the Discussion section to aid interpretation of the reported heterogeneity statistics.
5. We have now explicitly clarified in the Discussion section whether gratitude was implemented as a core component or as an adjunct within mindfulness-based interventions and briefly discussed how this distinction influences the interpretation of the observed effects.
6. This point has been clarified in the Limitations section in line with the reviewers’ previous comments.
7. We have revised the Results and Discussion sections to improve clarity by making minor stylistic refinements, including breaking up long or complex sentences, as suggested by the reviewer.

Reviewer 4 Report

Comments and Suggestions for Authors

The article addresses an important aspect of recent scientific research, mental health. In the context in which the academic communities are increasingly interested in researching techniques for providing the necessary help for the overall mental well-being, this article provides significant emphasis on mindfulness as a technique meant to counter anxiety, depression, and stress. 

The introduction offers a framework for the importance of the research, and, at the same time, covers the theoretical approach and the conceptualization of the variables measured by the research. The authors define the concepts, yet offering additional studies that support the relationship between neuroticism factors and mindfulness would complete the framework and would offer leads to the psychological mechanisms by which mindfulness counters depression, anxiety, and stress. The authors also discuss gratitude as an emotional resource that promotes resilience and well-being.

The section of materials and methods covers the research strategy, yet the authors don't specify how AI tools were used in formulating the research design. The study selection is accurately explained, and figures are provided to ensure understanding and a synthesis. The data analysis procedures are also described, as well as the risk of bias.

The objectives and hypotheses of the study, however, are missing from this section. The authors need to insert them in the text.

The authors provide an overview of the studies' selection, clustered by countries, research design, and type of mindfulness interventions used. Measured variables, effect sizes, and the duration of the interventions were also considered. A comprehensive table is provided to synthesize the most relevant aspects. The authors ensure a critical approach by describing the risks and limits of the studies that were considered for the research.

The section of statistical analysis offers an appropriate overview of the main indicators that were considered, with tables that support the results the authors obtained. The authors state that the regression test for publication bias was statisti-308 cally significant (p = 0.021), indicating potential asymmetry in the funnel plot and suggesting the presence of publication bias in the included studies, but they don't explain further the characteristics of the bias.

The discussion section offers additional explanations about the results and the psychological component hidden behind numbers and statistics. The references the authors use are appropriate. The discussion section provides an optimistic overall approach, as well as a critical one. 

 The conclusion section should also provide a reference to the objectives or the research questions.

 

Author Response

We thank you for your valuable comments, which have helped us improve the quality and clarity of our manuscript. In the revised version, all modifications made in the manuscript are highlighted in red.

We have clarified in the Materials and Methods section how AI-assisted tools were used during the research process, specifying their supportive role in study screening and organization.

The study objectives and hypotheses have now been explicitly added to the Materials and Methods section, as suggested.

We have added a brief explanatory statement in the Discussion section to further characterize the potential publication bias indicated by the regression test. This inadvertence has been addressed in line with the reviewers’ previous comments.

The Conclusion section has been revised to explicitly link the main findings to the study objectives and research questions.

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

The paper has been improved in a satisfactory way.

Author Response

Thank you!