15 Studies That Challenged Medical Dogma in 2019

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December 26, 2019

My favorite scientific papers are the ones that challenge the prevailing wisdom, or dogma. As I did in 2018, I've compiled a list of 15 such articles from 2019, in no particular order.

  1. New neurons proliferate in the hippocampus as we age, even into the ninth decade of life, researchers demonstrated in this paper in Nature Medicine.

  2. Novel protein-coding genes evolve on a de novo basis far more commonly than previously thought, according to an article in Nature Ecology and Evolution.

  3. Children's long bones grow with the help of a stem cell niche with a radical clonality switch that develops in the epiphyseal growth plate, according to research published in Nature.

  4. Are 10,000 steps really the activity goal we should be aiming for? Researchers who ran a study of nearly 17,000 women found the cutoff for mortality benefit was just 4400, they reported in JAMA Internal Medicine.

  5. Comparing the DNA of primary colorectal cancer tumors and metastases in the liver or brain revealed that for 80% of the 21 patients in the study, metastases took root early, researchers wrote in Nature Genetics.

  6. Typhoid toxin may not be required for people infected with Salmonella Typhi to develop typhoid fever, researchers found in this study in Nature Medicine.

  7. Assessing myocardial viability is not a helpful marker to predict the long-term outcome of coronary artery bypass grafting surgery, according to a randomized trial published in the New England Journal of Medicine.

  8. Rising body mass index among people living in rural areas ― not cities ― is the main driver of the global obesity epidemic, researchers reported in Nature.

  9. The brain microbiome: It might actually exist, and herpesvirus might play a role in Alzheimer disease, data published in Neuron in 2018 suggest. This year, the researchers responded to other scientists who pointed out issues they saw in the findings.

  10. Cardiac stem-cell therapy appears to work by stimulating the immunologic wound-healing process rather than generating new cells, according to research on mice published in Nature.

  11. Even if patients with severe aortic stenosis have no symptoms, early surgery to replace the aortic valve lowers their risk for death, researchers who ran a randomized clinical trial reported in the New England Journal of Medicine.

  12. Could we inherit mitochondrial DNA from our fathers as well as our mothers? A paper published in the Proceedings of the National Academy of Sciences in December 2018 purported to show evidence the answer is "yes." But as should be expected for such an extraordinary claim, other researchers challenged the scientists' interpretation of the data in 2019.

  13. Screen time: not so bad for kids' well-being after all? (Nature Human Behaviour)

  14. Maybe breakfast isn't really important. The morning meal may not help people lose weight, according to a meta-analysis published in the BMJ.

  15. Applying evolutionary game theory to cancer therapy, as researchers did in this paper in Nature Ecology and Evolution, challenges the traditional approach of blasting tumors with the maximum tolerable dose of chemotherapy.

What would you add to the list? Let me know with a comment here or on Twitter: @erictopol and @medscape.

If you read last year's list, here's an update to the first item: after more research, the placenta does not appear to have a microbiome, a Nature paper contends.

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