I’ve admired the cockroach’s ability to regrow lost legs since learning about them while working on my PhD in developmental genetics ages…
Reading a breathless account of an amazing new medical treatment, lured in by an exciting headline, only to discover a few paragraphs in that the findings are in rodents, can at best be annoying, and at worst raise false hopes for patients and their families. A new study, long overdue, pins down one source of this common error of omission: leaving out mice in the titles of technical articles.
A chain reaction of mangled communication is at fault.
Leaving Out the Rodents
Missing mice happen at several points in the medical news trajectory.
Failure to mention that an experiment was done on non-human animals in a technical article’s title can reverberate as a news release and then echo in media reports, tweets, and memes. Or, the headline of a news release or its content can ignore the mice, even if the journal article mentions them.
In yet another scenario, the reporter can omit the rodents. Journalists are sometimes so rushed with deadlines that they may modify a news release rather than take the time to read the technical report behind it that may indeed credit the mice and rats. Another source of the error: editors who write the headlines of news articles, omitting the mention (writers rarely write the headlines).
Many science journalists get ideas from the dozens of news releases posted daily at Eurekalert.org, from institutions and companies all over the world. And some releases only mention mice a few paragraphs in – or not at all.
Hype resulting from mouse-deficient headlines has bugged me for a long time. When I edit abstracts for a medical journal, one of my regular gigs, I alert authors who leave out model organisms from article titles.
So I was happy to read, ironically in a news release, that Marcia Triunfol at Humane Society International in Washington, DC and Fabio Gouveia at the Oswaldo Cruz Foundation in Rio de Janeiro have investigated whether mention of mice in news release headlines dampens media coverage.
The findings described in “What’s not in the news headlines or titles of Alzheimer disease articles? #InMice,” published in PLOS Biology, aren’t surprising: when a scientific paper’s title omits the rodent connection, journalists reporting on the paper tend to do the same. And reporters are more likely to cover papers without mice in their titles.
I’d never pitch an idea based only on mouse work to Medscape or MedPage Today, whose readers are clinicians. And I don’t include such studies in my human genetics textbook.
A Mouse Isn’t a Little Human
Mice are terrific models of some human diseases. Their anatomical, physiological, and genomic similarities to us make them useful in preclinical studies – emphasis on the PRE.
Testing a new treatment in mice is great for amassing large numbers, implementing several control groups, and doing things that one wouldn’t or couldn’t do to people, like yanking out a liver or slicing up a brain to study effects of a drug. Mice in particular are useful for studying aging, collapsing the timeframe of a lifetime from 80 years to 2.
For some diseases, exploring treatments first in a model organism makes sense. But the differences among species must be considered to jump from preclinical study to clinical trial. The correspondence can come down to a single gene. According to “Why Mouse Matters” at the NIH’s Genome.gov, “on average, the protein-coding regions of the mouse and human genomes are 85 percent identical; some genes are 99 percent identical while others are only 60 percent identical.”
Evolution has conserved large swathes of mammalian genomes. We use versions of the same molecules for the same things. But even when human genes are swapped into or added to rodent or monkey genomes, creating “humanized” creatures, differences in development impinge upon the extrapolation and interpretation of experimental results. This is particularly true for syndromes that unfurl according to a distinctive timetable, like genetic diseases with characteristic developmental delays or loss of milestones, and common chronic diseases that emerge and worsen over a lifetime, like diabetes and cardiovascular disease.
The imperfection of animal models isn’t a new idea.
A study of studies from 2005, “Of Mice and Men,” by Lloyd Demetrius, published in EMBO Reports, has a one-sentence abstract: “When it comes to studying ageing and the means to slow it down, mice are not just small humans.”
Demetrius examined the misplaced use of rodents in investigating aging and caloric restriction – the idea that near-starvation extends life. There’s evidence for the connection if you’re a rat. For people, not so much, although reducing eating may lower weight and blood pressure and cholesterol and glucose levels in the blood, which lowers risk of chronic conditions. He argued that the different developmental timetables of rodents and us reflect differences in the aging process itself, specifically metabolic responses to stress.
So you can’t extrapolate from mice living longer on a kale diet compared to littermates eating regular grub, to people making different dietary choices.
The new study probes the effect on media coverage of including, or not including, “in mice” in the title of a technical report about Alzheimer’s disease. They chose Alzheimer’s because it’s “an exclusively human condition,” but for which hundreds of mouse models have been developed to probe specific physiological responses not related to the passage of time.
The investigators divided 623 scientific reports published in 2018 and 2019 that used mice in Alzheimer’s disease research into those that outed the rodents in the title and those that didn’t. Then they tracked the news stories appearing in the wake of publication of each study.
The papers that left out mice received more media coverage and were significantly more highly tweeted. The authors expressed concern at the misleading of the public, even if unintentional.
“Most people only read the headlines of news stories. If the headline omits that the Alzheimer’s study was done in mice, most keep the impression that the study findings apply to humans, which is not true. We now know that virtually all findings obtained in animal studies in Alzheimer’s disease do not replicate to humans,” said Triunfol in the news release.
Alzheimer’s is only one example, but the failure to identify model organisms is pervasive and a practice not likely to fade away anytime soon. In fact, when I saw the news release that inspired this post, on EurekAlert, I read another, guilty of the mouse sin: “Plant-based diet protects from hypertension, preeclampsia.”
But here’s the first two sentences: “A plant-based diet appears to afford significant protection to rats bred to become hypertensive on a high-salt diet, scientists report. When the rats become pregnant, the whole grain diet also protects the mothers and their offspring from deadly preeclampsia.”
Will that headline alone trickle into news reports? Inspire tweets or Facebook memes? Probably. But the example of hypertension is less disturbing than Alzheimer’s – blood pressure is controllable in many ways, altering diet among them.
Headlines and news reports sensationalized, perhaps inadvertently, by errors of omission, will continue. So it’s up to readers to realize that dramatic claims of medical advances might not apply to people – caveat emptor.