Mapping the Mind–Body Connections: A Two-decade Bibliometric Exploration of Yoga and Psychoneuroimmunology

Abstract

Background

Over the past two decades, the intersection of yoga and psychoneuroimmunology (PNI) has received significant attention as a promising field for promoting mental and immune well-being. This bibliometric analysis explores global research trends, prolific authors, influential journals and collaboration patterns from 2003 to 2023. The study underscores the need to integrate traditional knowledge with modern science, positioning yoga as a validated tool in mainstream healthcare for disease prevention and management.

Purpose

This study aims to explore global contributions, impact trends in yoga and PNI research, prolific authors, journals and spotlight leading countries, emerging opportunities, influential research hubs and collaboration gaps. Additionally, to conduct thematic analysis aimed at integrating yoga into mainstream healthcare as a scientifically validated tool for promoting mental and immune well-being within the context of PNI.

Methods

Articles published between 2003 and 2023 were retrieved from Scopus and analysed using Biblioshiny version 4.0.0 (via R-Studio) and VOSviewer.

Results

A total of 2,173 publications were included. The average number of citations per document was 50.24. Although India is the birthplace of yoga, it still ranks fifth in terms of citations, behind the USA, Canada, the United Kingdom and Australia. It was observed that around 30%–50% of India’s publications (n = 239) involve international collaboration. The Canadian Institutes of Health Research and National Institute of Health dominate the funding landscape, whereas Indian funding agencies (Ayurveda, Yoga and Naturopathy, Unani, Siddha and Homeopathy, Indian Council of Medical Research and Department of Science and Technology) play a relatively minor role in the global context.

Conclusion

This analysis provides an updated perspective for understanding the field’s hotspot, which facilitates future research to uncover the mechanisms underlying the effects of yoga on the psycho-neuro-immuno-endocrine systems in disease prevention and management. Integration of traditional knowledge with modern scientific practices, with a focus on high-impact publishing, will help position India as a leader in this research domain.

Introduction

Psychoneuroimmunology (PNI) is a nascent field of study that was developed in Western science to explore the complex interaction among the nervous, endocrine and immune systems.^{1, 2} The term ‘Psychoneuroimmunology’ was first coined by Robert Ader, a psychologist in the late 1970s, following in his landmark 1975 experiment on the behavioural conditioning of the immune system. ³ Together with Ader’s contribution, other pioneers such as Nicholas Cohen and George Solomon firmly established that neural and endocrine factors could modulate the immune system. ⁴ Since its origin, PNI has developed extensively into an interdisciplinary science, bridging immunology, neuroscience, psychology and medicine. ⁵ Most importantly, PNI provided a scientific model for mind–body interactions, making it respectable to study how practices influencing the mind (e.g., stress reduction methods) might influence immune-related health outcomes. ⁶ This provided a conceptual basis for exploring traditional mind–body treatments like yoga using contemporary experimental methods. Around the turn of the 21st century, the paths of yoga and PNI started coming together, which led to the development of an interdisciplinary research domain. This multidisciplinary field contradicts the traditional biomedical model that treats these systems as distinct entities, instead highlighting a comprehensive understanding of health and disease. Ancient yogic literature has argued that mental control can affect physical health. Research in PNI has shown that the brain can influence immune function through various mechanisms, including the hypothalamic-pituitary-adrenal (HPA) axis and the autonomic nervous system. ⁷ Stress activates the HPA axis, triggering the release of cortisol, which can inhibit immune responses. ⁸ On the other hand, the immune system signalling molecules, such as cytokines, can alter neurotransmitter activity and lead to behavioural changes, such as fatigue and reduced motivation. ⁹ PNI has important implications for understanding the onset and progression of autoimmune diseases, infections and even cance.^{1, 2} It also offers a framework for exploring mind–body practices, such as yoga and meditation, which may impact these complex interactions to enhance health and well-being. ¹⁰

Yoga and PNI research have progressed tremendously over the past few years, as a function of technological innovations and new health concerns. Technological developments, including genomics, epigenetic assays and high-throughput immune profiling, are providing increased insight into yoga’s effects on immune cell gene expression profiles and telomere biology. ¹¹ The growing field of PNI highlights the connections between mental, neurological and immune functions, challenging the conventional biomedical model, which often separates aspects of health. ¹² This perspective aligns well with holistic healthcare principles, which view well-being as a comprehensive experience that includes physical, mental, emotional and even spiritual dimensions. ¹³ Yoga, an ancient mind–body practice that is gaining scientific support, exemplifies this holistic approach and shows great promise as a psychoneuroimmunotherapy. ¹⁴

Bridging the Mind–Body Gap

PNI research reveals the two-way communication pathways between the brain and the immune system, influenced by psychological factors such as stress. ¹⁵ Studies like those by Sharma and co-workers^16–19 explore how yoga effectively reduces stress and anxiety, which are crucial in immune balance. Studies of Streeter and co-workers^{14, 20, 21} underscores yoga’s beneficial effects on autonomic function, stress responses and immune resilience. The literature currently highlights certain populations and conditions, including depression and trauma, as the focus of yoga–PNI research. ²² Later studies have had higher methodological quality, with large multicentre trials ongoing or published in recent years, and systematic reviews and meta-analyses examining the impact of yoga on inflammatory markers or numbers of immune cells. This nascent discipline is now coming of age and transitioning to self-evaluation and meta-evidence synthesis.

Harnessing Neuroplasticity

Neuroscience highlights the brain’s adaptive capacity. ²³ Mindfulness-based yoga fosters neuroplasticity, improving areas related to emotional regulation, attention and self-awareness. ²⁴ These changes enhance stress response and immune function. Brain imaging is being employed to map brain-immune correlates of yoga practice and to elucidate mechanisms such as neural circuits that mediate stress reduction and subsequent immune effects. ²⁵

Beyond Symptom Management

Holistic healthcare focuses on addressing the underlying causes of illness rather than merely alleviating symptoms. ²⁶ Yoga fosters self-regulation, stress management and emotional balance, potentially preventing the onset of diseases or slowing their progression.^{23, 27} Its personalised approach allows adaptation to specific health needs. ²⁸ The coronavirus disease 2019 (COVID-19) pandemic has accelerated research on tele-yoga and remote mind–body interventions for mental health and immune-related outcomes.^{29, 30} Preliminary reports indicate that even virtual yoga interventions can reduce stress, cortisol levels and inflammatory markers in high-stress groups.

Integrating Ancient Wisdom with Modern Science

The philosophical foundations of yoga align with holistic principles, emphasising interconnectedness, self-awareness and mindful living. ³¹ Contemporary science is beginning to validate these ancient concepts, providing empirical support that strengthens the case for yoga as a legitimate psychoneuroimmunotherapy. However, challenges remain, including lack of standardisation in yoga practices ³² and the need for rigorous research to establish clinical guidelines. ³³

Despite these challenges, the intersection of insights from PNI, neuroscience and holistic healthcare strongly indicates that yoga has considerable potential as a psychoneuroimmunotherapy. ³⁴ Further research should focus on validating this potential and integrating yoga into mainstream healthcare as a complementary strategy.

This study explores the scientific connections between yoga and PNI through bibliometric analysis charting the development and direction of research in this field. This analysis will illuminate the growth of this research domain, identify gaps in knowledge and ultimately enhance our understanding of yoga’s therapeutic potential within the context of PNI.

Methods

Software and Tools Used in the Analysis

To conduct this bibliometric research, a comprehensive search was conducted using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines for the systematic review of articles included in the bibliometric analysis in Scopus database on 6 October 2024 to retrieve all relevant articles. The methodology adopted and database used were as per earlier publication. ³⁵ Scopus database was used as it is considered as the largest citation and abstract database extending its scope on a wide range of subjects. ³⁵ Scopus was selected as the sole database instead of PubMed and Web of Science for the following reasons: Scopus’s multidisciplinary coverage, including complementary medicine, along with comprehensive tracking and bibliometric analytics such as the CiteScore, h-index and field-weighted impact factors, makes Scopus a single robust search tool. In addition, a large proportion of PubMed-indexed journals are indexed in Scopus too, making a separate PubMed search redundant. The bibliometric tools used in this study, Biblioshiny and VOSviewer, are better integrated with data collected from Scopus, making it preferable for visualisation-based analysis. Furthermore, Scopus provides more frequently updated and readily available published research than Web of Science. ³⁶

The bibliometric data analysis was conducted using Biblioshiny (version 4.0), an interface of the bibliometrix R package (R Studio version 2024.09.0 + 375). In addition, this study also utilised MS Excel 365, VOSviewer (version 1.6.19) and Zotero (version 7.0.15) software.

Data Exploration and Plan

This study consists of four main stages: data acquisition, data preprocessing, statistical calculation and bibliometric analysis. Developing a search strategy with suitable keywords is regarded as the foundation for the analysis. To achieve this, the authors reviewed over 100 articles to identify key terms central to the theme of ‘Psychoneuroimmunology and Yoga’. The search phrases related to yoga and PNI were incorporated into the search strategy. While mind–body techniques are not strictly part of yoga, they include elements of yoga within a broader mindfulness-based framework, so we also included articles that examined the effects of these techniques on the connections between mental, emotional and physical health. Only peer-reviewed journal articles in the final stage (no preprints or early access versions), published in English from 2003 to 2023 and covering medicine, neuroscience, psychology and health sciences were prioritised. Articles focusing on yoga as a cultural, philosophical or religious practice without a scientific or physiological component, as well as yoga research on its effect on purely social or behavioural outcomes without neurological or physiological measures, were excluded. Studies focusing on animal models and other therapies were excluded. Editorials and opinions were also excluded. The search query, developed using the Boolean operators, field-specific tags, wildcard operators, along with the filters used to gather the relevant articles, are presented in Table 1.

Table 1. The Search Criteria Used to Retrieve Relevant Articles.

Database	Search Key	Filter
Scopus	TITLE-ABS-KEY ((yoga OR ‘yoga therapy’ OR meditation) AND (‘psychoneuroimmunology*’ OR stress AND psychological OR ‘immune system’ OR ‘nervous system’ OR ‘neurological’))	Publication year 2003–2023 English language Final publication stage Article

Notes: The methodical search approach used to find pertinent literature in the combined fields of yoga and PNI is described in this table. The Boolean search string was designed to find publications about yoga, yoga treatment and meditation with neurological processes, immunological function and psychological stress. This search approach was created to optimise the comprehensiveness of the retrieved studies while preserving their applicability to the research objectives. PNI, psychoneuroimmunology.

By means of this initial search, a total of n = 3,710 publications were yielded. Limiting the search to English-language articles of the document type published between 2003 and 2023, we extracted n = 2,173 documents. The first stage of data acquisition is thus accomplished.

The subsequent phase of data preprocessing utilised the PRISMA methodology^{37, 38} as illustrated in Figure 1. It should be noted that the steps outlined are for review purposes only and do not constitute a systematic literature review according to PRISMA guidelines. This analysis focuses on documents that studied the effects of yoga, meditation and related mind–body practices on stress, immune response, nervous system function, inflammation, autonomic regulation (vagal tone and HPA axis) or cortisol levels. Articles investigating mechanisms underlying yoga’s impact on health, such as neuroplasticity, neuroimmune reactions or physiological stress markers, were included. Randomized controlled trials, cohort studies, observational studies, systematic reviews and bibliometric analyses that had psychological, neurological or immune-related outcomes were included. To ensure consistency in article selection, two authors, H. D. and D. C. M., conducted a screening of the database independently to identify documents relevant to the analysis. The inter-rater reliability was assessed using Cohen’s kappa coefficient, yielding κ = 0.887, indicating almost perfect agreement. Any disagreements that arose during the selection process were resolved through discussion between the two authors before final inclusion. Missing or inconsistent data (e.g., incomplete bibliographic entries, missing metadata fields or inconsistent formatting) were automatically identified and excluded by the built-in preprocessing features of the Biblioshiny software before analysis. Hence, manual removal or additional cleaning procedures were not necessary, as the software inherently ensures data consistency and reliability for subsequent bibliometric analyses. This marks the completion of the second stage of data preprocessing.

Figure 1. A Comprehensive Method for Systematically Identifying, Screening and Selecting Appropriate Articles Included in this Review Is Depicted in the Flow Diagram, Which Follows the PRISMA Protocol.

The following phase of bibliometric analysis entails the statistical calculation of the data. ³⁵ This was carried out using a combination of the Scopus database, MS Excel 365, Zotero and Biblioshiny, which is an interface of the bibliometrix R package. These tools were employed to evaluate and visualise the data, providing the necessary outcomes to fulfill the objectives of this study. This concludes the third stage of statistical calculation in bibliometric analysis.

The next stage of application analysis utilises MS Excel 365, VOSviewer and Zotero to create knowledge maps, thesaurus files and validate data. In this phase, the final dataset of 2,151 articles was completed following the steps outlined in the PRISMA flow diagram and then exported to VOSviewer ³⁹ to visualise the bibliometric knowledge map derived from the dataset.

Results

Out of the 2,173 documents, only 2,151 have complete metadata fields that Biblioshiny can use. The 22 documents that did not qualify for the analysis had incomplete information, such as cited references and science categories.

Research Growth Trend: Analysis of the Publication

This statistical analysis section illustrates the historical trend of articles published in the Scopus database considering the theme of ‘yoga and PNI’.

Figure 2 shows that the evolution of scientific publications was relatively low in the early years (2003–2008), with fewer than 50 articles per year, indicating the nascent stage of this field. Starting around 2008, publication rates steadily increased, surpassing 150 articles by 2013, reflecting a growing awareness of the importance of mind–body practices, such as yoga, in PNI for mental and physical health. From 2013 to around 2021, research output continued to rise, eventually reaching a peak of over 200 articles per year. This peak may be attributed to the COVID-19 pandemic, which sparked greater interest in interventions aimed at managing stress and enhancing immunity. After 2021, there has been a slight decline, though the number remains higher compared to earlier years. This could be due to a consolidation phase, where foundational research has already been established, funding limitations or shifting priorities within research institutions.

Figure 2. This Graphical Illustration Highlights the Steady and Considerable Increase in the N number of Scientific Articles Published Each Year Between 2003 and 2023. This Trend Highlights the Growing Interest and Active Participation in the Areas Researched by This Study.

The annual growth rate was calculated using the formula:

$$\text{Annual Growth Rate }(\text{\%})=\left({\left(\frac{v_f}{v_i}\right)}^{1/n}-1\right)\times 100$$

where v_f is the final value (e.g., number of publications at the end of the period), v_i is the initial value (e.g., number of publications at the beginning of the period) and n is the number of years between the initial and final values and was found to be 13.17% between 2003 and 2023.

Prolific Journals and Articles

The results illustrate the most relevant journals contributing to research on yoga, mindfulness and related interventions. Table 2 lists the leading journals in the field of yoga and PNI, their most cited article and other metrics.

Table 2. The Top 10 Most Prolific Journals in the Combined Field of Psychoneuroimmunology and Yoga, Along with Their Highly Cited Articles.

Sl No.	Journals	CiteScore *2023	No. of Articles Published	Highly Cited Article	Citations	Publisher
1	Journal of Alternative and Complementary Medicine	4.2	67	10.1089/acm.2008.0495	1129	Mary Ann Liebert Inc.
2	Mindfulness	6.1	44	10.1007/s12671-010-0023-4	256	Springer
3	International Journal of Environmental Research and Public Health	5.6	43	10.3390/ijerph17186450	122	MDPI
4	Complementary Therapies in Medicine	5.3	36	10.1016/j.ctim.2010.09.008	229	Elsevier
5	PLOS ONE	7.1	36	10.1348/147608310X526511	620	Public Library of Science (PLOS)
6	Complementary Therapies in Clinical Practice	4.2	33	10.1016/j.ctcp.2009.01.002	383	Elsevier
7	Explore: The Journal of Science and Healing	2.7	28	10.1016/j.explore.2008.10.001	362	Elsevier
8	Frontiers in Psychology	4.9	27	10.3389/fpsyg.2015.00093	189	Frontiers Media
9	BMC Complementary Medicine and Therapies	4.8	26	10.1186/1472-6882-7-2	143	BioMed Central
10	Integrative Cancer Therapies	5.1	25	10.1177/1534735409331456	192	SAGE Publications

Notes: The 10 most productive journals publishing research at the intersection of yoga and PNI are shown in this table. Based on the number of relevant articles published, the CiteScore (2023) indicates the impact and citation frequency of these journals. The ‘Highly Cited Article’ column lists a representative article with high citation influence, demonstrating the contribution of the journal to the field; the ‘Citations’ column shows the number of times the highly cited article has been referenced in other scholarly work. PNI, psychoneuroimmunology.

Table 2 highlights publication evolution in yoga and PNI, showing a strong concentration in complementary and multidisciplinary journals. Notably, mindfulness has emerged as a key platform, reflecting the growing scientific interest in mind–body practices over the past two decades. Unlike complementary medicine, mindfulness specifically addresses mental health, neuroscience and the intersection with mind–body practices.

The dominance of journals such as the Journal of Alternative and Complementary Medicine, Complementary Therapies in Medicine and Explore indicates that the combined studies of yoga and PNI remain largely within the Complementary and Alternative Medicine framework. Despite significant involvement of medical practitioners in PNI research, regular medical journals remain sidelined in terms of publishing opportunities, likely due to thematic relevance and targeted readerships.

Besides, multidisciplinary journals such as PLOS ONE and Frontiers in Psychology suggest that the researchers in yoga and PNI seek to publish their work for a broader readership. Furthermore, BMC Complementary Medicine and Therapies and Integrative Cancer Therapies indicate that this area integrates well with health research on chronic and cancer patients, thus shifting the focus of the field to yogic therapy and its clinical efficacy.

Prolific Authors

The Table 3 highlights the contributions of the most prolific authors in the field of yoga and PNI, showcasing the dominance of researchers primarily affiliated with Western institutions. Leading the list is L. E. Carlson, affiliated with Canada, whose extensive research output (22 articles) and high citation count (3,258 citations) underline Canada’s prominent role in advancing mind-body research. Similarly, authors such as R. J. Davidson, A. Lutz and K. W. Brown, primarily associated with institutions in the United States and Europe, reflect how Western researchers and institutions have historically driven this field’s academic momentum.

Table 3. List of Most Prolific Authors in the Combined Field of Psychoneuroimmunology and Yoga.

Sl No.	Name of the Author	First Article Published Year	Articles Published	h-Index	Total Citations
1	L. E. Carlson	2003	22	21	3,258
2	R. J. Davidso	2010	18	11	1,201
3	S. B. S. Khalsa	2009	17	10	555
4	J. A. Dusek	2009	14	8	810
5	K. W. Brown	2009	13	12	1,928
6	A. Lutz	2010	12	10	1,542
7	H. R. Nagendra	2007	12	8	843
8	M. Speca	2003	11	11	6,411
9	J. D. Creswell	2009	11	9	1,794
10	S. Nidich	2006	11	9	583

Notes: The 10 most prolific authors who have contributed to yoga and PNI research are listed in this table. The ranking of authors is based on the total number of publications in the field. Each author’s first pertinent publication in this field of study is shown in the ‘First Article Published Year’ column. The ‘Total Citations’ column measures the total impact of the authors’ publications, while the h-index shows the impact and citation influence of each author. PNI, psychoneuroimmunology.

Table 3 also reveals a significant insight into the relative underrepresentation of Indian researchers. While yoga originates from India and holds deep cultural and traditional significance, H. R. Nagendra, with 12 publications and 843 citations, is the only Indian-origin author on this list. Despite India being the birthplace of yoga, it appears that the academic frameworks and funding priorities in India have not sufficiently propelled Indian researchers to dominate this field. The emphasis on international collaboration in India’s yoga research—where 30%–50% of publications involve foreign partners—further suggests that much of India’s contributions may not be independently driven.

The dominance of Western authors in this field highlights a broader pattern: Western institutions have robust research ecosystems, significant funding from bodies such as the National Institutes of Health (NIH) and Canadian Institutes of Health Research (CIHR), and access to multidisciplinary collaborations across neuroscience, psychology and immunology. These factors have enabled researchers like R. J. Davidson and A. Lutz to explore yoga’s mechanisms, such as neuroplasticity and stress regulation, through cutting-edge scientific methods. Meanwhile, Indian researchers, despite having access to rich cultural knowledge and traditional practices, seem to lack equivalent systemic support for generating impactful and globally recognised research in yoga and PNI.

This disparity underscores the need for Indian funding agencies such as Ayurveda, Yoga and Naturopathy, Unani, Siddha and Homeopathy (AYUSH), Indian Council of Medical Research (ICMR) and Department of Science and Technology (DST) to not only increase investments in yoga-related research but also prioritise high-impact publishing and international visibility. Strengthening research training programmes and encouraging interdisciplinary approaches could position Indian researchers at the forefront of this field, leveraging their cultural heritage with modern scientific methods. Ultimately, the table illustrates how Western researchers and institutions have effectively capitalised on yoga’s therapeutic potential, bridging traditional practices with modern PNI frameworks. For India, this serves as a call to action to reclaim its leadership in the academic exploration of yoga by fostering a globally competitive research ecosystem.

Most Productive Countries, Academic Institutions and Collaborations

To provide a comprehensive view of researchers and their affiliated academic institutions’ global distribution, Atlist was utilised in Google Maps to pinpoint their locations. Figure 3 illustrates the worldwide mapping of the top 10 most productive countries and their academic institutions, with names displayed according to their ranking based on research contributions in the combined fields of yoga and PNI. The data from Google Maps indicates that the European region leads in publications related to this area.

Figure 3. An Informative Chart Identifying the Top 10 Highest-productivity Countries and Institutions Significantly Contributing to the Joint Discipline of Psychoneuroimmunology and Yoga. The Figure Points Out Global Scholarly Leadership and Institutional Distinction.

Table 4 presents the most productive countries along with the academic institutions that are publishing and contributing to the field. This study focuses solely on academic institutions for the sake of brevity, as it is intended for an academic audience, and therefore excludes non-academic institutions. Figure 4 illustrates the global co-authorship network in yoga and PNI research and Figure 5 shows the global distribution of research efforts.

Table 4. Tops 10 Productive Countries Along with the Most Relevant Affiliations in the Combined Field of Psychoneuroimmunology and Yoga.

Sl No.	Country	Total Articles Published by the Country	No. of Articles Published From a Single Country	Educational Institution	Total Articles Published by a Given Educational Institution
1	USA	816	731	University of California	114
2	India	164	154	All India Institute of Medical Sciences	50
3	Canada	100	81	University of Calgary	63
4	Australia	94	66	University of Melbourne	58
5	United Kingdom	73	52	University College London	54
6	Germany	61	36	Charité–Universitätsmedizin Berlin	52
7	China	55	41	Peking University	49
8	Italy	53	42	University of Milan	47
9	Spain	39	23	University of Barcelona	45
10	Korea	37	31	Seoul National University	43

Notes: The top 10 countries are ranked here by the total number of yoga and PNI articles they have published. The number of research conducted only in that country is shown in the ‘No. of Articles Published from a Single Country’ column; cross-country collaborations are not counted here. The most productive institutions in each country are also emphasised in the table, ranked by their collective contributions to the discipline. This table indicates significant centres of scholarly production in this area and provides information on the pattern of research across the globe. PNI, psychoneuroimmunology.

Figure 4. A Visually Engaging Bibliometric Knowledge Map Displaying Co-authorship Networks. The Connections Illustrate Collaborative Relationships Among Researchers, Highlighting Clusters of Active Scholarly Partnerships and International Collaboration Within the Research Community.

Figure 5. The Figure Reflects How National Research Outputs Have Evolved, Providing a Historical Perspective on Global Contributions and Trends in the Field.

Author Keywords, Thematic Map and Future Conduits

The Scopus file containing 2,173 articles was exported to VOSviewer for a co-occurrence analysis of the author keywords, as illustrated in Figure 6. A total of 3,623 keywords were recorded. VOSviewer met the threshold value of 261 after applying a minimum occurrence criterion of five. Following the removal of synonymous words and phrases, the final count of keywords stands at 175, which meets the minimum occurrence requirement. The network analysis comprises 14 clusters; the items in each cluster are provided in the Supplementary file. There are 1,942 keyword co-occurrence links, highlighting robust thematic interconnections and indicating considerable interdisciplinary dialogue within the field. The total link strength of 5,645 suggests a densely interconnected thematic landscape. Higher total link strength implies significant co-usage of keywords across multiple studies, reflecting coherent thematic integration. The visualisation results in VOSviewer, as shown in Figure 6, indicate that ‘mindfulness’ is the most prominent keyword, with 159 links and a total link strength of 1,291. Both yoga and mindfulness are central to studies focused on managing stress, anxiety and depression, as they play a role in regulating the HPA axis and promoting neuroplasticity. The terms heart rate variability, cytokines and inflammation suggest a focus on how yoga and meditation affect autonomic nervous system function and immune responses, which are core aspects of PNI. Research often links yoga and mindfulness to conditions such as breast cancer, fibromyalgia, hypertension and obesity, highlighting their role in enhancing quality of life and resilience in chronic diseases. Emerging research areas are evident, with terms such as ‘telomere’ and ‘spirituality’ reflecting a growing interest in exploring yoga’s effects on cellular ageing and existential well-being. Additionally, the mention of burnout and workplace stress underscores the importance of yoga in occupational health. The inclusion of keywords such as ‘nutrition’, ‘massage’ and ‘tai chi’ points to the integration of complementary therapies alongside yoga within holistic health frameworks.

Figure 6. A Density Visualisation Created Using VOSviewer That Vividly Illustrates the Co-occurrence of Author Keywords. Prominent Keywords Indicate Central Themes and Topics Frequently Explored by Researchers, Providing Insights into Prevailing Research Interests.

Due to methodological constraints (limited temporal subdivisions and data points within the entire study period), the Biblioshiny software was unable to generate a valid thematic evolution visualisation. Therefore, an alternative analytical strategy was adopted by segmenting the overall study period (2003–2023) into five distinct intervals (2003–2007, 2008–2012, 2013–2017, 2018–2023 and overall 2003–2023) and generating individual thematic maps for each interval. This approach enabled detailed visualisation of thematic dynamics, clearly revealing shifts in central themes, emerging areas of interest and changes in thematic density and centrality over time.

The thematic map analysis across four time periods indicated a distinct trend in yoga and PNI research. In the first period (2003–2007), themes were mainly concerned with psychological adaptation and broader perspectives on alternative medicine. Subsequent periods showed methodological improvement, with increased focus on human studies, targeted physiological markers (e.g., cortisol) and systematic clinical outcome measures. In the most recent years (2018–2023), the science matured into strong clinical confirmation, with a salient emphasis on mental health (anxiety and depression) and the conduct of stringent randomised controlled trials. Importantly, the advent of COVID-19-related research reflected responsiveness to global health phenomena, although this theme is also ephemeral. Overall, these results describe an evolutionary shift away from exploratory studies towards clinically targeted, mechanism-based and methodologically rigorous research in the field.

The thematic map for the overall period (2003–2023), as illustrated in Figure 7, categorises various themes according to their relationship between the degree of relevance (centrality) and the degree of development (density).

Figure 7. A Thematic Analysis Map That Provides a Clear Visual Summary of the Main Themes Found by Keyword Clustering. The Conceptual Framework and Theme Linkages Between Yoga and PNI Research.

Note: PNI, psychoneuroimmunology.

Motor themes, located in the top-right quadrant, are both well-established and highly pertinent to the field, often propelling the research area forward. The inclusion of treatment outcomes, psychological factors and clinical trials as motor themes suggests that these subjects are central to ongoing research and are well-developed. This indicates that exploring the results of interventions and their psychological impacts is a crucial and evolving area of study.

Basic Themes (bottom-right quadrant) serve as the foundation for further exploration. Topics such as psychology, mindfulness and anxiety highlight that these concepts underpin much of the research in this domain. Mindfulness and anxiety are critical subjects often examined in relation to how practices such as yoga and meditation may help alleviate mental health issues. The use of general terms such as ‘human’, ‘humans’, and ‘article’ as basic themes indicates a broad interest in human responses to interventions, though often lacking detailed specialisation.

Niche Themes (top-left quadrant) are specialised and well-developed, yet not central to the wider research field. The mention of physiology, hydrocortisone and heart rate points to an emphasis on the physiological responses to interventions such as yoga or mindfulness. This niche area likely investigates biomarkers such as cortisol (hydrocortisone) levels or heart rate to comprehend the physical effects of psychological interventions. These subjects are vital for understanding the underlying mechanisms of stress reduction or the physiological consequences of mind–body practices, although they may not receive as much attention compared to broader themes such as psychology or mindfulness.

Emerging or Declining Themes (bottom-left quadrant) are characterised by low centrality and low density, indicating they are either new areas of study or topics that are losing significance. Terms such as COVID-19, pandemic and coronavirus disease 2019 reflect their prominent but waning importance, with focus shifting back to more established areas such as general mindfulness or clinical trials.

Future Conduit

The focus on clinical trials and treatment outcomes underscores the importance of ongoing empirical validation for various interventions. There is an opportunity to better integrate physiological aspects such as heart rate and cortisol into broader research themes. Bridging these physiological biomarkers to psychological outcomes could provide a more holistic research framework. As pandemic-related research declines, focus may turn to the long-term effects of yoga and mindfulness on mental health, reinforcing their role in addressing anxiety, stress and overall well-being. This analysis highlights the current state of the field and suggests opportunities for integrating physiological findings into the broader research framework.

Discussion

Key Findings

This bibliometric analysis provides a comprehensive exploration of the scientific synergy between yoga and PNI over the past two decades, mapping the field’s evolution, key trends and influential contributors. It emphasizes the growing endorsement of yoga as a therapy that integrates immunological, neurological and mental health benefits, supporting the emerging integrative healthcare model. The United States has contributed the most in terms of research publications, followed by Canada, the United Kingdom and Australia. India ranks fifth in research output, as its volume and citation influence remain below those of these countries. Large international agencies such as the CIHR and the NIH in the US dominate the funding landscape, based on analyses of grant acknowledgements. Indian funding agencies, including AYUSH, ICMR and DST on the other hand, are relatively under-represented. The international visibility and contribution of yoga research from India remains limited despite the significant contribution of funding from AYUSH and other Indian institutions. Major focus themes such as stress reduction, immune modulation, mental health and inflammation position yoga–PNI research to align well with the integrative healthcare paradigm that seeks holistic wellness approaches.

Implications for Research Policy, Funding and Collaboration

The absence of Indian agencies from the global funding arena provides India’s institutions and government with a strategic window to increase yoga–PNI research funding priorities. This creates a need for Indian funding agencies such as AYUSH, ICMR and DST to increase their investment and promote high-impact research and publications for international visibility. This will allow India to transition from being a facilitative collaborator to becoming a principal leader in this domain. Increased funding can enable the establishment of research centres with a specific focus, such as mind–body research institutes, high-tech immunological assay labs and neuroimaging facilities, where national researchers can undertake large-scale and rigorous studies. Disbursement of funding in order of precedence for the areas known to be growing can help funnel resources into areas of high scientific potential and public health significance.

International research policy needs to create and sustain global partnerships that bring together complementary skills. Multinational collaborations can be facilitated through co-funded opportunities, enhanced scientific quality and increased research capacity in underdeveloped regions of the world. Policies to alleviate hindrances to international cooperation, such as travel bursaries, exchange visits and streamlined ethics/governance arrangements, would be appreciated.

Organisations like the World Health Organization (WHO) have already begun to provide high priority to research in integrative and traditional medicine, initiating the WHO Global Centre for Traditional Medicine in India. Prioritising funding for yoga–PNI research can be two-sided: advancing science and supporting global goodwill for global health. A balanced approach is recommended in funding, where national funding initiatives in countries with a rich mind–body heritage provide separate grants for research related to PNI in yoga.

Practical and Research Implications

The expanding body of knowledge in yoga and PNI has serious implications for numerous stakeholders in health and research. Academics and researchers can utilise this bibliometric data (mapping of prolific authors, journals and collaboration networks) to design influential research and identify the key journals (for instance, those publishing the most impactful yoga–PNI studies), thereby helping researchers to target venues that will maximise the visibility of their work. Awareness of dominant research hubs and active collaboration networks enables scientists to forge partnerships with leading groups, whether in the United States, Europe or emerging centres in Asia. By highlighting trending topics (e.g., yoga for inflammation or mental health), this analysis also guides researchers towards pressing questions and avoids duplication of well-explored areas. In essence, the bibliometric data serve as a strategic tool to plan impactful research and multidisciplinary collaboration.

Over time, as research continues to validate specific protocols, clinical guidelines may incorporate yoga sessions for conditions where mental and immune factors intersect (such as depression with inflammation, cancer-related fatigue or autoimmune disorders). Clinicians and healthcare practitioners can apply it to recommend evidence-based strategies for stress, rehabilitation and chronic disease care. The increasing scientific credibility of yoga–PNI also encourages hospitals and spas to create integrative care programmes, including yoga therapy services for patients.

Training programmes and educators must develop curricula in integrative health science to ensure that future researchers and clinicians are familiar with both ancient yogic principles and contemporary scientific techniques. Building human resource capacity through education will produce a new generation of professionals skilled in both yoga practice and biomedical research, which will be critical for the future development of the field.

Decision makers and health systems may leverage the evidence of yoga’s increasing influence on mental and immunological well-being to make policy-level choices regarding research and healthcare infrastructure. In nations such as India, where yoga has cultural significance, country-wide programs can be expanded as a component of preventive and promotive approaches to health. Insurance providers and health systems may consider covering yoga-based interventions, thereby enhancing access for patients.

Research infrastructure can be improved by creating dedicated centres of excellence for the study of mind–body and by developing more efficient databases and knowledge bases for the study of traditional medicine. Support for yoga–PNI research is not only intellectual but can also influence the provision of more holistic, improved healthcare globally.

Strengths and Limitations

The study uses a comprehensive and exhaustive approach, such as a robust database retrieval from Scopus, advanced bibliometric tools and a lengthy time frame (2003–2023) to cover the evolution and growth of yoga–PNI research. The study provides multidimensional insights by examining various dimensions, such as top authors, top journals, country-level contributions, collaboration networks and thematic and keyword analyses. Key research trends are charted, and a comparative analysis of India and Western countries reveals regional variations and areas where research collaboration, funding and policy can be enhanced. The pattern of funding is also analysed, with institutions like the NIH and CIHR being dominant and Indian institutions having lower representation. Visualization tools like knowledge maps, thematic maps and co-occurrence networks make the manuscript more readable. The study successfully integrates indigenous knowledge with modern science and fosters more culturally relevant and efficient healthcare services globally. Implications of the study for the future of research and policy recommendations are made, in addition to the translational utility and practical use of the study. The study also presents a critical analysis of rigor and high ethical and reporting quality.

This bibliometric analysis of yoga and PNI literature has the following limitations:

1. Data source bias: The study relied on Scopus as the sole database and predominantly English-language journals, which may underrepresent studies in other languages or local journals that are not indexed by Scopus.

2. Citation biases: Earlier published works (2003–2021) have had greater opportunities to accumulate citations, while more recent works (2022–2023) have had less chance to cite due to the lack of proper exposure in circulation. Additionally, highly prolific authors or countries might dominate citation metrics, but this does not automatically equate to proportional scientific advancements, as the quantity and quality of output can differ. Self-references and differential citation patterns among fields can distort the quality of output as well.

3. Search strategy and terminology: The results of the study will be determined by the terms and search strategy used to locate ‘Yoga and Psychoneuroimmunology’ literature. PNI is interdisciplinary in nature, and as such, relevant studies may be categorised under other keywords without explicitly mentioning PNI. Terminology inconsistency in the area poses a problem, as different styles or degrees of yoga may affect neuroimmune outcomes differently.

4. Heterogeneity of methods: Over 20 years included in the studies are not uniform. Bibliometric analysis does not align findings to the quality of the study or strength of evidence, and collaboration network analysis and author impact can be marred by the way author names and affiliations are presented.

5. External drivers: The effect of drivers like the COVID-19 pandemic that influence publication patterns also needs to be considered. These are not part of the quantitative analysis but are significant when interpreting spikes or shifts in the data.

Future Research Directions

Based on the current bibliometric analysis, we recommend improving inclusion and sources of evidence, applying standardisation of procedures and vocabulary, studying mechanisms, conducting longitudinal studies and clinical trials, embracing diversity of use and fostering global cooperation. Expansion of data sources (WoS, PubMed, IndMED and grey literature) and inclusion of articles in non-English languages can compensate for database and language bias. Uniformity in protocols and nomenclature is also needed to maximise literature searches and enable inter-study comparisons. Mechanistic and translational research needs to be performed to elucidate the biological pathways by which yoga’s effect on the brain-immune axis is achieved. ⁴⁰ This may be done by studying the effects of yoga interventions with sophisticated immunological assays, imaging or genomic strategies. The cause-and-effect relationship and certain biomarkers in response to yoga intervention can be studied using translational research on animal or cellular models of immune dysregulation following stress. Clinical trials and comparative effectiveness studies with larger, more diverse populations and longer follow-ups to assess clinical effects are recommended. Synthesising evidence and findings, as well as evidence-based recommendations through meta-analyses, will become achievable as the field matures. Diverse applications in areas such as autoimmune disease, infectious disease outcome or neurodegenerative disease in PNI are proposed. For generalisability, research can be carried out with diverse demographics, age groups, socio-cultural backgrounds and experience levels of yoga. International and multidisciplinary collaboration can be facilitated, with international consortia for yoga–PNI studies enabling multicentre trials and cross-national data sharing. This has the potential to generate high-level evidence and cross-cultural generalisability, as well as facilitate the exchange of knowledge between Western laboratories and Indian or South Asian collaborators.

Research Policy and Funding Recommendations

In light of our findings and the future directions outlined, we finally offer specific recommendations for stakeholders in research policy and funding to develop special funding calls for research into applications of yoga-related practices, establish fellowships or chairs in integrative medicine and include such research in national health missions. Global health organisations (WHO, NIH, etc.) and philanthropic foundations ought to include yoga–PNI as part of their strategic research funding plans for global health. With the low-cost, low-risk profile of yoga, showing its effectiveness for preventing or managing chronic diseases could have high returns by decreasing healthcare burdens globally. Funding consortia could co-fund large projects (e.g., a multi-country trial of yoga for post-COVID mental health and immune recovery), sharing costs and expertise. Investments should be made in research projects and underlying infrastructure, such as biobanks for yoga study samples, data-sharing platforms and training institutions. Investments in state-of-the-art laboratories in traditional medicine universities or yoga institutes would facilitate high-quality local research and support international collaborations. Bibliometric and meta-research studies should be performed regularly to assess the development of the field and guide policy adjustments. Researchers need to be supported in publishing their work in high-impact, well-indexed journals and encouraged to pursue open-access publication or data sharing for easier access.

By implementing these strategies, research policymakers and funders will play a pivotal role in shaping the next chapter of yoga and PNI research. The collective effort will ensure that the promising trends observed in this bibliometric analysis translate into sustained scientific advancements, better healthcare policies and ultimately improved health outcomes through integrative approaches.

Conclusion

This study acts as a valuable resource for researchers, clinicians and policymakers by identifying key publication venues, collaboration networks and thematic areas of interest. Researchers can use these findings for effective collaborations and publication opportunities, while healthcare professionals can leverage these findings to enhance evidence-based integrative health practices. Additionally, funding organisations can use this data to promote an inclusive and globally representative research environment.

While this study has its strengths, it has limitations including its dependence on English-language databases, possible citation biases and the variability in yoga practices among different studies. Future research should broaden database coverage, standardise terminology and integrate both physiological and psychological outcomes for a comprehensive understanding of yoga’s effects on mind–body health. Standardising methodologies will improve replicability and strengthen yoga’s role in psychoneuroimmunological research.

As the field matures, rigorous, large-scale trials validate preliminary findings and refine therapeutic protocols. By aligning traditional knowledge with modern research standards, the integration of yoga into mainstream healthcare can be bolstered, transforming it into a scientifically grounded, globally accessible tool for enhancing mental, physical and immune well-being. This study not only maps the trajectory of yoga and PNI research but also lays a solid foundation for future inquiries, further bridging ancient wisdom with contemporary science.

Abbreviations

AYUSH, Ayurveda, Yoga and Naturopathy, Unani, Siddha and Homeopathy; BMC, BioMed Central; CIHR, Canadian Institute of Health Research; COVID-19, Coronavirus disease 2019; DST, Department of Science and Technology; HPA, hypothalamic-pituitary-adrenal axis; ICMR, Indian Council of Medical Research; NIH, National Institute of Health; PLOS ONE, Public Library of Science ONE; PNI, Psychoneuroimmunology; PRISMA, Preferred Reporting Items for Systematic Reviews and Meta-Analyses.

Authors’ Contribution

Study concept and design: H.D. Literature search and data extraction: H.D. and D.C.M. Data analysis: H.D. Manuscript preparation: H.D. and D.C.M. Critical revision: D.C.M.

Statement of Ethics

The study was exempted from institutional ethics review because only publicly available data were used and analysed.

ICMJE Statement

ICMJE disclosure form is submitted along with this manuscript.

Patient Consent

Patient and public involvement, as well as patient consent for publication, are not applicable for this study.