The use of acronyms in biomedical research papers has increased steadily over the past 70 years, a study of millions of scholarly articles has found.

The analysis, which included more than 24 million titles and 18 million abstracts of papers published between 1950 and 2019, identified 1.1 million unique acronyms that have been used in biomedical research¹. Unsurprisingly, DNA was found to be the most widely used acronym, appearing in titles and abstracts more than 2.4 million times.

The analysis found that the number of acronyms in both titles and abstracts has gone up. In 1950, paper titles contained an average of 0.7 acronyms per 100 words. This rose to 2.4 acronyms per 100 words in 2019. In abstracts, there were 0.4 acronyms per 100 words in 1956, and 4.1 per 100 words in 2019.

In nearly three-quarters of the abstracts analysed, the researchers found at least one acronym. But relatively few have stuck: just 0.2% of all the acronyms have been used regularly, and their popularity has changed over time. In the 1950s, the most commonly used acronym was ACTH, which stands for adrenocorticotropic hormone, a molecule produced by a pea-sized gland at the base of the brain. Over the years, increasing numbers of papers mentioning DNA, RNA and HIV have been published (see ‘Letters of note’).

Although abbreviations such as DNA and HIV have become widely spoken and understood, many others do not have immediately obvious meanings, says study author Adrian Barnett, a statistician at the Queensland University of Technology in Brisbane, Australia. This can cause confusion. Some of the most common acronyms in biomedical papers have different meanings depending on context — for example, US can stand for United States, ultrasound or urinary system.

Excessive acronym use might be encouraged by the influence of social-media platforms such as Twitter, which require brevity, as well as the belief that abbreviating phrases can sharpen a scientific article, says Colin Begg, an epidemiologist at Memorial Sloan Kettering Cancer Center in New York City. Begg, who is editor-in-chief of the journal Clinical Trials, has repeatedly called for scientists to reduce their use of acronyms in scholarly articles. However, he says, “it’s swimming against the tide”.

Barnett agrees. “At this time in history, science needs to be clear and understandable by the public and policymakers,” he says. “But we’re travelling in the wrong direction.”