Around this time every year, we start seeing blog posts for the top ten books of the past year and the top ten resolutions for the year ahead. These listicles help us to reflect and look forward.
This post is inspired by this seasonal spirit of list-making.
Every year, the National Library of Medicine (NLM) adds new concepts to the controlled vocabulary Medical Subject Headings (MeSH). As a reminder, NLM is one of our National Institutes of Health and is the institution behind PubMed, among other tools. Around this time each year, NLM adds new MeSH concepts. This may seem like something only librarians - particularly indexers - would get excited about, but the annual release of the new MeSH list is a reflection of research trends and priorities, as represented by the scientific literature.
Before I dive into the new concepts for 2021, a quick aside: what are medical subject headings? Subject headings are tags assigned to articles to increase findability. Imagine you are searching for articles on “soda”. Some authors write about soda, while others write about pop. It is best practice to use all synonyms of a term for the most comprehensive search. That’s where subject headings come in. A search using the subject heading for soda would return all articles, whether the authors use soda or pop or another term ( What term does your hometown use? Let me know in the comments below!).
Note, the “soda” subject heading search may also return articles for specific types of soda through automatic explosion - interested in learning more about this, also let me know in the comments!
Now, “soda” hasn’t always been around, and researchers have not always been writing about soda. The number of articles published on “soft drinks” has increased since the 1970s, as depicted by the graph below.
Trends in research are reflected in the papers researchers publish, and trends in biomedical research can be seen in the articles indexed in PubMed. Medical Subject Headings have to keep up to help users locate papers on new technologies like “automated facial recognition” and “surgical navigation systems” or specific fungi and bacteria of increasing interest and clinical importance
| Tree Location | Number of New Terms for 2021 |
| ascomycota | 12 |
| actinobacteria | 8 |
| basidiomycota | 5 |
| cyanobacteria | 5 |
| actinomycetales | 2 |
| clostridiales | 2 |
| gram negative | 2 |
In the new MeSH terms for 2021, perhaps unsurprisingly, we see a number of headings related to COVID-19, from the physiological (i.e. Angiotensin-Converting Enzyme 2) to the socioeconomic (i.e. teleworking). Remember when the first tweets, anecdotes, and news stories came out on loss of smell as a clinical sign? A 2020 search for “loss of smell” in PubMed would be mapped to “olfaction disorders”. In other words, the algorithm found the closest subject heading and searched for that as well as similar keywords to expand the search. However, in 2021, your “loss of smell” search might be mapped to the more specific heading “anosmia”, which will be applied to newly indexed articles.
Certainly COVID has dominated publishing in 2020. What else is trending? The word cloud below depicts the most frequently used words in the subject headings and scope notes in the New MeSH Headings for 2021. Ascomycota, bacteria, family, fungi, genus, phylum, and species might all be indicative of the new headings for specific bacteria and fungi. Viral, virus, and covid also appear. There are other terms, too, that reflect a broad view of health and medicine. Behavior, food, social - these and other terms are seen relatively frequently.
We see, for instance, subject headings related to structure, society, and psychology, some of which were added to integrate into MeSH terminology from the NIH Office of Behavioral and Social Sciences Research (for instance, Correctional Facilities; Food Deserts; Models, Biopsychosocial; Water Insecurity) an expansion of the biomedical to address the impact of various factors on individual health. There appears to be interest in whole-person health ( which is also likely a reflection of work published during COVID), for instance “financial stress” and “food security”. We see terms for different hobbies and activities, “marathon running” and “internet use”.
| Tree Location | Number of New Terms for 2021 |
| food supply | 4 |
| psychotherapy | 3 |
| social behavior | 3 |
| behavior addictive | 2 |
| human rights | 2 |
| interpersonal relations | 2 |
| social problems | 2 |
| socioeconomic factors | 2 |
| stress psychological | 2 |
Every year, changes in language are often reflections of dramatic social shifts, and 2020 is certainly no exception. Want to learn more about the 2021 MeSH terms? Find out What’s New in MeSH for 2021 and, as always, Ask a Librarian for help using MeSH in your search strategy.
