3.1. General Trends in the Publications and Citations

We included a total of 67,386 publications related to anxiety disorders, three times the number of articles included in previous study (22,267) [11]. The reason is that Liu et al. [11] only obtained publications from the Science Citation Index subdatabase which focused on the natural sciences and did not include publications in the SSCI subdatabase. The chart showed the trends in annual publications and citations from 2000 to 2023 (2024 was not a full year and was not shown in Figure 2).

From 2000 to 2023, the annual publication volume and citations of publications related to anxiety disorders showed a significant growth. From 2000 to 2007, the number of publications per year was between 1000 and 2000, between 2000 and 3000 from 2008 to 2000, and 3000–4000 from 2013 to 2020, and the number exceeded 4000 from 2021 to 2023. 2022 was the peak year for the number of annual publications (reaching 4992), 4.99 times the number in 2000.

3.2. Distribution Characteristics of Countries/Regions

In total, 164 countries/regions globally participated in the anxiety disorder research. Table 1 presents the top 20 countries ranked by the number of publications. The United States (26,919 counts, 1,296,489 citations) ranked first in terms of the number of publications and all cited. It was followed by the United Kingdom (6824 counts, 301,752 citations), and the third was Germany (5612 counts, 254,276 citations). Among the top 20 countries, Belgium had the highest average citation (50.74 citations), followed by France (49.14 citations), and the third was United States (48.16 citations).

The average publishing year of 20 countries was generally between 2014 and 2016, among which the average publishing year of United States was the earliest, and the average publishing year of China was the latest, which ranked sixth in the number of publications, indicating that China’s research on anxiety disorder had increased significantly in recent years (Table 1).

Figure 3 illustrates the global distribution of the 164 countries/regions that participated in the research on anxiety disorders. Countries/regions with more than 5000 publications were in red, countries/regions with 1000–4999 were in orange, countries/regions with 100–999 were in dark green, countries/regions with 10–99 were in yellow, and countries/regions with 1–9 were in light green. It can be seen that almost all of the world had contributed to anxiety disorders research, with North America, East Asia, and Oceania leading the way.

3.3. Analysis of Highly Productive Journals

Four thousand fifty-four journals had published publications on anxiety disorder research. Table 2 showed the top 20 journals in publication volume. The Journal of Affective Disorders (n = 1861 counts) was the most prolific magazine in this field, followed by the Journal of Anxiety Disorders (n = 1389 counts) and the Behaviour Research and Therapy (n = 1211 counts). The Behaviour Research and Therapy (n = 80,094 citations) was the journal with the highest total citations, followed by the Journal of Affective Disorders (n = 58,077 citations) and the Journal of Anxiety Disorders (n = 58,017 citations).

Of the top 20 journals, the one with the highest average citations was Biological Psychiatry (n = 112.23 citations). The earliest journal in average publication year was Biological Psychiatry (2009.61), and the latest journal in average publication year was Frontiers in Psychiatry (2021.21).

We set the threshold for journal publication to 100, and 132 high-yield journals were obtained. There were 38,478 publications in 132 high-yield journals, accounting for 57.10% of all publications. We used VOSviewer to perform citation analysis on 132 high-yield journals and constructed overlay visualization map (Figure 4). The size of circle represented the amount of publications, and the color from blue to red represented the average number of citations from low to high. There were 19 journals with on average more than 60 citations (shown in red).

3.4. Analysis of High-Yield Institutions

There were 31,577 institutions involved in the publication of anxiety disorders articles, and the top 20 institutions ranked by the number of publications were shown in Table 3. Harvard University was far ahead of other institutions in both the number of publications (2389 counts) and the number of citations (176,341 citations), Columbia University was second in the number of publications (1544 counts), and the third was King’s College London (1328 counts). The second in citations was Columbia University (123,595 citations), and third was Yale University (71,904 citations).

Among the top 20 institutions, Columbia University had the highest average citation (80.05 citations), followed by Harvard University (73.81 citations) and Massachusetts General Hospital (66.28 citations). Among the top 20 institutions, University of California, San Diego, had the earliest average publication year (2012.44), and Karolinska Institute had the latest average publication year (2017.27).

Of the top 20 institutions, 12 institutions were from the United States, 3 from the Netherlands, 2 from the United Kingdom, and 1 each from Canada, Sweden, and Australia.

We set the threshold 150 publications for institutions and identified 206 high-yield institutions from 31,577 institutions. We used VOSviewer to conduct coauthorship analysis on 206 high-yield institutions, all of which were in a coauthorship network, as shown in Figure 5, consisting of 8 clusters.

The red cluster was the largest, consisting of 73 institutions. Harvard University was the largest node, in close cooperation with the Massachusetts General Hospital and the Boston University, all of which were from American. The second was the green cluster, consisting of 51 institutions, and King’s College London was the largest node, with close cooperation with University College London and University of Oxford, all of which were British. The dark blue cluster was the third largest, and consists of 24 institutions, and the Dresden University of Technology was the largest node, with close cooperation with the University of Wurzburg and University of Basel, which were all German.

Harvard University cooperated with 199 high-yield institutions, followed by Columbia University with 183 high-yield institutions, and University of Toronto and Yale University with 182 high-yield institutions.

3.5. Visualization of Coauthorship Analysis of Authors

There were 206,496 authors which participated in anxiety disorder publications, and the top 20 authors by number of publications were shown in Table 4. Storch, Eric A. (n = 411 counts) were the most prolific authors, followed by Dan J. Stein (n = 377 counts) and Brenda WJH Penninx (n = 311 counts). Kessler, Ronald C. (n = 67,145 citations) were the most cited authors, followed by Dan J. Stein (n = 27,348 citations) and Stein, Murray B (n = 26,248 citations). Of the top 20 authors, Kessler, Ronald C. (n = 271.84 citations) had the most average citation times, followed by Wittchen, Hans-Ulrich (n = 104.94 citations) and Stein, Murray B. (n = 101.74 citations). Stein, Murray B. had the earliest average publication year (2009.89), and Storch, Eric A. (2015.87) had the latest average publication year.

We set the threshold of author publications to 60 and identified 164 high-yield authors. We used VOSviewer to perform coauthorship analysis on 164 high-yield authors (Figure 6), and 160 of the 164 high-yield authors formed the largest coauthor network, consisting of 12 clusters. Dan J. Stein collaborated with 77 high-yield authors, followed by Christine Lochner with 62 high-yield authors, and Eric A. Storch with 57 high-yield authors.

We counted the research areas of eight authors with more than 250 publications, as shown in Figure 7. We made specific statistics on the top five research areas with the most published articles by the eight authors, and the rest were classified into others. Psychiatry was the largest research area for seven of the eight authors; other significant research areas included clinical psychology, psychology, clinical neurology, neurosciences, etc.

3.6. Analysis of Highly Cited Articles

Table 5 shows the top 20 highly cited articles. The highly cited one of the 67,386 articles was Robert L. Spitzer’s article, named “A brief measure for assessing generalized anxiety disorder: the GAD-7” [16]. The study developed a short self-report scale based on questionnaires and telephone interviews with mental health professionals from 15 primary care clinics in the United States. Comparing the GAD self-report scale diagnosis with an independent diagnosis by a mental health professional confirmed that GAD-7 was an effective tool for screening for generalized anxiety disorders and assessing disease severity in clinical practice and research. Ronald C. Kessler’s article named “Lifetime prevalence and age-of-onset distributions of DSM-IV disorders in the National Comorbidity Survey Replication” was close behind in citations. The study was a nationally face-to-face household survey of 9282 English-speaking respondents aged 18 years and older, using a comprehensive international diagnostic interview from the fully structured version of the World Health Organization’s World Mental Health Survey [5]. The result was that about half of Americans would meet the criteria for DSM-IV disorder at some point in their lives, usually with first onset in childhood or adolescence, so interventions need to focus on youth. The citations of these two papers were far ahead of the others.

The psychological impact of the COVID-19 epidemic on college students in China ([7], IF 11.3); generalized anxiety disorder, depressive symptoms, and sleep quality during COVID-19 outbreak in China [7]; and a web-based cross-sectional survey ([17], IF 11.3) [17], global prevalence, and burden of depressive and anxiety disorders in 204 countries and territories in 2020 due to the COVID-19 pandemic [18] were the representative papers published in the past 4 years. However, the number of citations ranked in top 20. On the one hand, these papers were of high quality, and on the other hand, anxiety and depression caused by novel coronavirus were also hot topics in recent years, with great potential.

3.7. Keyword Analysis

There were 53,765 author keywords in 67,386 articles. We set the threshold for high-frequency keywords to 80 and obtained 394 high-frequency author keywords. The co-occurrence analysis of 394 high-frequency author keywords was performed, and the co-occurrence network map of high-frequency author keywords was constructed. The co-occurrence analysis of 394 high-frequency keywords formed 5 clusters, represented by different colors. The red cluster was composed of 116 author keywords and was the largest cluster. Cluster 1 (red) represented etiology and pathogenesis, Cluster 2 (green) represented clinical classification and interventions, Cluster 3 (blue) represented comorbidity, Cluster 4 (yellow) represented anxiety caused by the COVID-19 pandemic and specific groups, and Cluster 5 (purple) represented anxiety disorders in children and adolescents, focusing on five research topics (Figure 8).

We also built overlay map for 394 high-frequency author keywords (Figure 9). The color of each node in the figure represents the average publication year of that node, becoming increasingly new from blue to red.

4.1. General Information

In this study, we analyzed 67,386 articles on anxiety disorders obtained from the WoSCC, providing an in-depth analysis of the literature by country, institution, journal, author, and keyword. Judging from the number of annual publications, the extensive and close scientific collaboration, the dense citation network, and the numerous subject areas involved, there is no doubt that anxiety is still at a hot phase. The life, career, and financial changes caused by the COVID-19 pandemic have been associated with worsening mental health, which may be responsible for the sharp increase in the number of publications on this topic in 2020−2022 [7, 17–20].

There were 164 countries/regions; almost all regions of the world participated in anxiety disorder research, especially North America, Europe, East Asia, and Oceania. The leading position of the United States in the field of anxiety disorders was solid. Of the 67,386 articles we included, the United States topped the list with 26,919 in absolute terms, significantly outpacing other countries. The United States had six of the top 10 research institutions by output and four of the top 10 journals published. All these indicated that the robust national research capabilities of the United States and its substantial contributions to this field. Although Belgium ranked 11th in the volume of research outputs, it was the highest in terms of total citations, followed by France and the United States in third, which indicated that these countries had a certain influence in the study of anxiety disorders. Also of note was China’s rapid growth, with the latest average publication year (2019) indicating great potential for future research.

As for contributing institutions, Harvard University in the United States was the core institution of anxiety disorder research. Harvard University ranked first in the world in both the number of research outputs and the cited publications, which illustrated that Harvard University was the most influential institution and the quality of the published literature was widely recognized by peers. However, none of the Asian institutions made it to the list of top 20 institutions in terms of scientific output or most cited publications on anxiety disorder research. In terms of international research cooperation in this field, the cooperation between countries/regions was very extensive; the United States, the UK, and Germany were more influential. Notably, Harvard University also was the center of global research collaboration in this field, with 199 high-output research institutions, the closest being Boston University and Massachusetts General Hospital in the United States. In addition, renowned research institutions such as Columbia University, University of Toronto, and Yale University had established substantial collaborative networks, engaging with over more than 180 institutions each. But our analysis revealed that there was a high degree of cooperation among the developed European and American countries, with much less collaborative activity with institutions in developing countries. Moreover, the pattern of cooperation between these institutions tends to be relatively fixed. It is necessary to strengthen cross-regional collaboration among global institutions to ensure a broader and more diverse contributions, which is essential in future research in key areas of anxiety disorders.

The author’s analysis can objectively evaluate the contribution of the researchers, as well as their research level and academic standing on the topic. Professor Eric A. Storch from Baylor College of Medicine in the United States produced the most research documents in this field with 411 publications, plus with the latest average publication year, indicating his continuing influence in the field. Following Eric A. Storch is Dan J. Stein from the University of Cape Town in South Africa and Brenda WJH Penninx from Vrije Universiteit, Amsterdam, in Netherlands. We found that most of the authors came from universities and hospital institutions, and the most active scholars with the most research achievements contributed greatly to clinical psychology, psychology, clinical neurology, and neuroscience, especially as they formed a close scientific cooperation relationship. The three groups with the highest link strength were centered on Dan J. Stein from the University of Cape Town in South Africa, Christine Lochner from Stellenbosch University in South Africa, and Eric A. Storch from Baylor College of Medicine in the United States.

Remarkably Professor Ronald C. Kessler from Harvard Medical School in the United States was the most cited author in both total and average citations times, indicating that he had a very high level of influence in the field and his articles were of very high quality and worth studying.

4.2. The Hotspots and Frontiers

Highly cited references form the source of a knowledge base for a particular subject area. The top 10 cocited references were mainly related to the following aspects attracting researchers: (1) development and validation of the screening assessment tools for anxiety disorders [16, 21, 22]; (2) epidemiological evidence [5, 23]; (3) psychiatric disorders in childhood and adolescence [3, 24]; (4) comorbidity of anxiety disorders [25, 26]; and (5) the psychological impact of the COVID-19 epidemic [7].

Keyword analysis can help us understand the hotspots and frontiers in the field. In the high-frequency keyword analysis, the main focus was on five clusters, which shaped the current research trends in anxiety disorders.