Bibliometric analysis of the BDNF Val66Met polymorphism based on Web of Science, Pubmed, and Scopus databases

The BDNF Val66Met polymorphism is a genetic variant that has been implicated in neurological and neuropsychiatric disorders. The aim of this study was to determine and quantify the state of the art of scientific publications related to this polymorphism based on the Web of Science (WoS), PubMed, Scopus and Biological Abstracts databases. Data retrieval was performed by the terms "BDNF" and "Val66Met" on May 24, 2012. For quantitative analysis we assessed the total number of articles, authors, countries, institutions, scientific journals and years of publication recovered with this research strategy. Our results showed that WoS contains the largest number of records (771), followed by PubMed (474), Scopus (454) and Biological Abstracts (321). The latter database was not used in subsequent analyzes due to fewer records. According to the top 20 lists generated, the author with the greatest number of articles was Tsai SJ according to WoS and Scopus, appearing as third in PubMed (21, 12 and 9 records, respectively). In addition, the second most productive author, Kennedy JL, only appeared in WoS and Pubmed (19 and 5 records, respectively), while Bath KG only appeared in WoS and Scopus (11 and 9 records, respectively), and Taylor WD only in WoS (9 records). The database with broadest global coverage including countries with publications on this subject was Scopus, followed by PubMed and WoS (44, 42 and 39 countries represented, respectively). The United States was the largest contributor to these databases. Mexico appeared with one record mentioning this polymorphism in both Scopus and PubMed. Moreover, the three main institutions that published on the subject were the University of Toronto (28 records), King's College London (24 records) and the National Institute of Mental Health (24 records) according to WoS; while according Scopus these were the King's College London, Veterans General Hospital-Taipei and the National Institute of Mental Health (21, 18 and 16 records, respectively). We could not obtain this information from PubMed with the recovery/analysis tools available to us. Finally, the analysis for scientific journals showed that the American Journal of Medical Genetics Part B Neuropsychiatric Genetics (50, 30 and 21 records in WOS, PubMed and Scopus, respectively), Genes, Brain and Behavior (26 in WOS and 22 in both PubMed and Scopus), Neuroscience Letters (30, 22 and 21 in WOS, Scopus and PubMed) and Molecular Psychiatry (23, 15 and 11 in WOS, Scopus and PubMed), are the main journals publishing about the BDNF val66met polymorphism. Our bibliometric analysis showed important differences between the three databases analyzed with our search strategy: number of articles recorded, more productive authors, countries represented, and the journals that concentrate most articles on the BDNF val66met polymorphism. In addition, we observed an increasing trend in the study of this polymorphism since it was first reported in 2002 (WoS and PubMed), as expected for genetic variants associated with distinct clinical conditions. Bibliometric analysis are important not only to make visible that exploring multiple databases is a requirement to retrieve all the information relevant to our topic of interest but also for decision-making about possible research groups to collaborate, and journals to publish as well as to define or maintain research lines.