Child psychiatry: A scientometric analysis 1980-2016

Background: The field of child and adolescent psychiatry lags behind adult psychiatry significantly. In recent years, it has witnessed a significant increase in the publication of journals and articles. This study provides a detailed bibliometric analysis of articles published from 1980 to 2016, in the top seven journals of child and adolescent psychiatry. Methods: Using the Web of Science core collection, we selected 9,719 research papers published in seven psychiatric journals from 1980 to 2016. We utilized the Web of Science Analytics tool and Network Analysis Interface for Literature Studies (NAILS) Project scripts to delineate the general trends of publication in these journals. Then, co-citation analysis and hierarchical cluster analysis was performed using CiteSpace to map important papers, landmark theories and foci of research in child and adolescent psychiatry. Results: The field of child and adolescent psychiatry has experienced an increasing trend in research, which was reflected in the results of this study. Hierarchical cluster analysis revealed that the research foci in psychiatry were primarily studies related to the design of psychometric instruments, checklists, taxonomy, attention deficit hyperactivity disorder (ADHD), depression, PTSD, social phobia, and psychopharmacology. Moreover, several landmark studies, including the validation of a child behavior checklist, Ainsworth's empirical evidence of Bowlby's attachment theory, and adult outcomes of childhood dysregulation were published. This study also reports rapid expansion and innovation in research areas in the field of child and adolescent psychiatry from 1980-2016. Conclusions: Rapid expansion and innovation in research areas in the field of child and adolescent psychiatry has been observed, from 1980 to 2016.


Introduction
Mental health disorders are very prevalent among children and adolescents, resulting in a significant impact on society. It is estimated that 13-20% of children living in the United States (1 out of 5 children) suffer from a mental disorder every year, resulting in an annual economic loss of 247 billion USD 1 . Despite these statistics, the field of child psychiatry has attracted a little research interest as compared to other specialties of medicine. This is evident from the fact that not even a single article related to mental health among children was published in the first 45 years of the publication history of American Journal of Insanity 2 . In a clinical context, the first ever hospital specializing in the treatment of sick children; La'Hôpital des Enfants-Malades, was established in 1802 on the Rue deSévres in Paris. It was also the first time that the field of pediatrics was recognized as an established specialty of medicine 2 . Institutions specializing in mental health of children, however, did not develop until after World War I, when August Hamberger established his outpatient clinic in the University of Heidelberg 3 . Experts believe that child psychiatry evolved as a separate field after America's first juvenile court was established in 1899 4 . Then, during World War II, Great Britain started to patronize the psychological development of its children, for a better future 5 . Similar strides were made in the US, when President Harry Truman declared war on mental illness in 1946, after signing the National Mental Health Act that led to the birth of the National Institute of Mental Health 6 . This resulted in an explosion of research in understanding the nature of psychiatric diseases, its diagnoses and taxonomy and psychopharmacological and behavioral treatments. At present, child and adolescent psychiatry has established itself as a distinct specialty globally, however, major disparities exist between the developed and third world countries 7 .
While the development of infrastructure and facilities in any field of medicine are important, scientific research, new discoveries and influential publications are the true marker that ensure its constant progress and evolution. The history of research and development in child psychiatry is quite intricate; spanning discoveries in several domains of medical and social sciences. It is very important to map the research output in a field, to help guide policy makers, researchers and funding agencies towards areas where restriction or increase in research activity is required. In recognition of its importance, several reproducible statistical methods were developed under the umbrella of scientometrics. It is the "quantitative study of science, communication in science, and science policy", helping to evaluate the impact of journals, scientists and institutes on the development and innovation of a scientific field 8 .
The present study analyzes the trends of research in the field of child and adolescent psychiatry by employing reproducible scientometric techniques. Although several scientometric studies have been published in general psychiatry 9,10 and other fields of medicine, there is a paucity of such studies mapping the research output in the field of child psychiatry, hence warranting this study. The present study identifies influential publications, landmark theories, authors, countries and major funding agencies contributing to child psychiatry from 1980-2016.

Methods
For the purpose of this scientometric analysis, we selected seven journals (Table 1) indexed under the term "Child Psychiatry" in Google Scholar. These journals were selected on the base of their ISI impact factor, h5-index and h5-median, following the methodology of previous scientometric articles published in the field of psychiatry 9,10 . The Web of Science core collection was utilized to download bibliographic records of articles published in these journals from 1980-2016 to provide an overview of recent advances in this field. These records included title, author names, abstract, key words and cited references. This search was performed in December, 2016 and records for a total of 9,719 articles, published during 1980-June 2016 were retrieved. There were no restrictions based on type or language of articles included in this analyses.
This study utilized three software tools for analyses of data; Web of Science core collection records, Network Analysis Interface for Literature Studies (NAILS) Project scripts 11 and Citespace (v4.0 R5, Drexel University, Pennsylvania, USA) 12 . The Web of Science core collection-online analysis platform was used to document journal wise influential authors, institutions, funding agencies and countries. NAILS software was utilized to analyze these to identify the most cited keywords in these journals.
of document co-citation 13,14 , co-citation relationships between two documents exist when they are cited together by another document.
Using "time slicing", the bibliographic records were divided into four groups according to the year of publication; 1980-1990, 1991-2000, 2001-2010 and 2011-2016, the year per slice was set to 1 with each year represented by top 50 articles based on the number of citations. The 'team source' selects were 'title', 'abstract', 'author keywords' and 'keywords plus' and the 'node types' selected were 'cited reference'.
Network analyses were run with the link reduction method using pathfinder network scaling and then, bibliographic records for each 10-year slice were visualized separately. Articles were represented as nodes and lines as edges. Using this technique, several key results could be identified, such as new theories/concepts related to a field (visualized as a purple ring), centrality reflecting the status of a publication in their network/field, citation bursts (hot topics of research), citation tree rings representing year-wise citation pattern of a node (article). Articles with centrality values > 0.1 were considered as significant entities controlling significant resources in their collaborative networks. Based on these techniques, researchers can observe and understand bibliographic trends in order to identify patterns of research in particular fields and regularities of citations in particular time periods 15 .  (Table 1), from 1980 to June 2016. All journals publish multidisciplinary research articles in the fields of child and adolescent psychiatry, ensuring constant improvement and evolution of the field toward a cutting-edge, evidence-based clinical specialty. Figure 1 shows the yearly publication volume in the field of child and adolescent psychiatry since 1980, and documents the rapid increase in publication volume in this field since the 1980s. The publication output in these journals rose from less than a 100 journal articles in 1980 to more than 500 in 2015. Figure 2 shows the yearly trend in the number of citations received by articles included in our analyses. The articles were cited a total of 1,37,006 times, however, this number dropped to 1,27,119 after removing selfcitations. The total number of articles citing these publications was 81551 (77853 after excluding self-citations). Average citations per item were 16.85, contributing to an h-index of 132. The increasing trend in publication ensures that the field of child psychiatry is constantly evolving because of new discoveries in epidemiology, assessment techniques, genetics, neurosciences and therapeutics. However, the research output in journals related to child psychiatry still lags behind those of general psychiatry and other specialties of medicine 16 .

Top institutions, authors and countries
It is interesting to note that the highest output of research in child psychiatry comes from institutions in developed countries. According to Albayrak et al., this regional disparity is attributed to a high GDP of these countries, higher funding available and availability of more public health resources, specialty training programs and mental health professionals committed to the field of child psychiatry 7 Table 2).
Most cited keywords from 1980 to 2016 According to our analysis, the top foci of research in child psychiatry correspond with most common mental health conditions globally. Figure 3 details the top cited keywords, representing the top foci of research in these selected journals ( Figure 3). Top cited psychopathologies were depression, attention deficit hyperactivity disorder (ADHD), autism, anxiety, conduct disorder, obsessive compulsive disorder, post-traumatic stress disorder, bipolar disorder, suicide and aggression. This is in accordance with Polanzcyk et al., who identified the worldwide prevalence of any anxiety disorder to be 6.5%, any depressive disorder to be 2.6%, ADHD to be 3.4%, and any disruptive disorder to be 5.7% 17 . Methylphenidate was identified as the top cited keyword for a drug used in child psychiatry. Our results are in accordance with López Muñoz et al., who reported methylphenidate to be the most researched drug for attention deficit hyperactivity disorder (ADHD), also correlating it with an increased trend in its use 18 .

Publications from 1980 to 1990
In further analysis, CiteSpace was used to identify important articles based on their centrality values. Articles with centrality values > 0.1 were considered significant. These articles were considered important within their collaborative network, focused on a specific research domain (Table 3, Figure 4). Visualization of these clusters also helped in identification of purple nodes that represent important and groundbreaking theories, and represent a link between two different clusters 12 .     Figure 4 represents a visual co-citation network of 412 research documents published in the field of child psychiatry from 1980-1990. The rings represent several key results such as new theories/concepts related to a field (visualized as a purple ring), centrality reflecting the status of a publication in their network/field, and citation tree rings representing year-wise citation pattern of an article. Development of questionnaires and rating scales specific to child psychiatry is another milestone in its history. Like any other scientific discipline, this allowed researchers and clinicians to reliably quantify emotional problems among children and Other important publications explored the relationship between the caretakers and the child. Bowlby's attachment theory propounded that a child initially forms only one attachment relationship, and this attachment figure becomes a base for all future relationships 26 and disrupting this, can lead to long term consequences. Ainsworth's studies provided the first empirical evidence of Bowlby's attachment theory 26 , which was subsequently explored in a longitudinal study by Egeland and Sroufe 27 . In a similar context, Gaensbauer & Sands' study on the therapeutic relationship between abused/neglected infants and their caretakers, which concluded that personality traits of the child may contribute to disturbance in caretaker-infant interaction, leading to abuse and neglect 28 . All of these studies represented significant between-ness centrality in this time period.
Publications from 1991 to 2000 There were 315 nodes and 508 edges in this time period (Table 4, Figure 5). In recent decades, the integration of epidemiological evidence into child psychiatry, has truly helped it reach its scientific potential. This specific discipline helped child psychiatry in three principal ways: a) identify the burden of childhood psychiatric illnesses b) identify new risk factors for psychiatric illnesses and c) explore the validity and reliability of diagnostic statistical manual.
During this period, several landmark epidemiological studies were conducted. There were three studies focusing on suicide, PTSD and ADHD. The most important paper with a centrality value of 0.34, identified as a purple node was entitled, "Risk factors for adolescent suicide: a comparison of adolescent suicide victims with suicidal inpatients" by Brent et al. 29 Table 5 provides a detailed analysis of the articles selected based on their centrality values. Please, note that some of these articles were published in the previous decade but they influenced other research in this decade.

Publications from 2001 to 2010
There were 306 nodes and 483 edges (Table 5, Figure 6). An eminent scientist in the field of child psychiatry, Angold et al.    Interview Schedule for Children Version IV (NIMH DISC-IV) with its previous versions, and its reliability for some common diagnoses 57 .
In this decade, a lot of pharmacological research was guided by several influential studies on depression, anxiety and ADHD among children. The most important paper with a centrality value of 0.26 and identified as a purple node was titled "Treatment for adolescents with depression Study (TADS) Team: Fluoxetine, cognitive-behavioral therapy, and their combination for adolescents with depression" by March et al. 58 . This study concluded that the combination of CBT and SSRI is the most efficacious for treating major depression among adolescent population. It also helped guide the National Institute for Health and Clinical Excellence (NICE) guidelines for treating adolescent depression.
Another trial proved that fluvoxamine is efficacious in childhood and adolescent anxiety disorders 59 . The MTA Cooperative Group tested the treatment strategies for ADHD 60 and also identified the moderators and mediators of treatment response for children with ADHD 61 . This was one of the most influential study guiding future research on treatment of ADHD. Since 1999, when the NIMH study was published, thousands of additional peer-reviewed studies have been published on the topic of ADHD treatment.

Publications from 2011 to 2016
There were 209 nodes and 313 edges (Table 6, Figure 7). "The fifth edition of Diagnostic and statistical manual of mental disorders (DSM-5)" was identified as the most important publication. 62 .  Willcutt et al. 63 reviewed the validity of DSM-IV attention deficit/hyperactivity disorder symptom dimensions and subtypes. Our analysis identified two important works in epidemiology; elucidating the prevalence of childhood psychiatric disorders. In his metaanalysis, Polanczyk analyzed the causes for worldwide variation in estimates of ADHD 64  The data is also accessible via the Clarivate analytics Web of Science Core database.

Discussion
The field of child psychiatry is still a relatively new and expanding field, in comparison to other specialties of medicine. It has evolved significantly over the last few years. Most of the literature in this field was contributed by United States of America and the European countries, with small contributions from the developing countries. Similar trends were observed in the regional distribution of funding agencies and authors contributing to this field. Several pharmaceutical industries were also identified among top ten funding agencies. A number of landmark papers and research foci were also identified. During the first three decades, the researchers focused on assessment tools, taxonomy, identification of risk factors, and symptomatology. Over time, there has been a growing interest in finding better assessment tools and more effective psychopharmacological options. However, more recently, there has been a rapid development in several areas including neurobiology, neuroimaging, and molecular genetics. Researchers are more interested in exploring etiological factors leading to psychiatric illnesses. The authors strongly believe that these innovative trends in the field would help identify and manage the childhood psychiatric disorders at an earlier stage, and also increase the quality of life among patients, their families and caretakers. The publication, Child psychiatry: A scientometric analysis 1980-2016 was read with enthusiasm and admiration. It is true that child and adolescent psychiatry significantly lags behind general adult psychiatry in producing valid clinically useful research. Assessing research output in a scientific field is of utmost importance as it provides a guide for the future development of that field. This article demonstrates the research output trends in child and adolescent psychiatry over the previous four decades. It allows us to generate an understanding of the future research trends and the gaps that should be addressed by researchers in this field.
The mapping of research output in a scientific field is an extremely difficult task. This is made even more cumbersome in the field of child and adolescent psychiatry, as there is an overlap of articles in fields of child psychiatry, child psychology, neuro developmental psychiatry and paediatrics. The authors have employed a sound technique to achieve this complex task by using reputed software such as Web of Science core collection records, Network Analysis Interface for Literature Studies Project scripts and Citespace.
The article highlights the emergence of new concepts in the discipline of child and adolescent psychiatry over the decades. It is interesting to note that some older publications influencing the field after many years from their initial publication.
Few limitations were considered for this publication. The authors have analysed articles of the journals with high impact factor at present. However, it should be noted that in the past different journals had higher impact factors for child and adolescent psychiatry. Many decades back certain reputed journals in general psychiatry published significant numbers of articles in child and adolescent psychiatry as journals dedicated only for this sub speciality were less popular. It is understandable logically that the authors selected the seven journals according to the current impact factors to make this project practical.
In relevance to the discussion, it would have been interesting to compare some aspects of the results of this study with similar scientometric analyses in other medical disciplines and General Psychiatry. The authors could have concentrated on research output related to aetiology, symptomatology and management compared to other fields of psychiatry and medicine. In future, it would be exciting to compare these results with other sub specialities in psychiatry such as forensic psychiatry, mental health related to intellectual disability, addiction psychiatry and old age psychiatry.
In conclusion, the authors have made a valid and practical attempt to assess and analyse the research output in the discipline of child and adolescent psychiatry over the past four decades. Further scientometric analyses are required to assess the impact of other influential publications in child and adolescent psychiatry published in journals known for general or other specified medical specialities.
Is the work clearly and accurately presented and does it cite the current literature? Yes

Are sufficient details of methods and analysis provided to allow replication by others? Yes
If applicable, is the statistical analysis and its interpretation appropriate? I cannot comment. A qualified statistician is required.
Are all the source data underlying the results available to ensure full reproducibility? Yes

Are the conclusions drawn adequately supported by the results? Yes
No competing interests were disclosed.

Competing Interests:
We have read this submission. We believe that we have an appropriate level of expertise to confirm that it is of an acceptable scientific standard.