July 29, 2019

What too much work does to your DNA. (Hint: It's not good.)

Daily Briefing

    The medical community has long debated whether medical residents are overworked, and a study published this earlier year revealed that "long hours, disrupted sleep and constant stress can take a biological toll on newly minted doctors," Dhruv Khullar writes for the New York Times' "Well."

    Learn more: The 4 ways you can fight physician burnout

    The medical resident aging problem

    Khullar, an assistant professor of health care policy at Weill Cornell Medicine, recalls being in his mid-20s, completing his medical residency when he found his first gray hair. "[I]t was the first time I'd noticed my body aging—not getting stronger or faster or wiser, but starting its decline," he writes.

    After that, Khullar found more grays, until he stopped counting.

    The aging process, Khullar determined, might have been due to his "intense, sometimes grueling" medical training. And a new study published in the journal Biological Psychiatry supports that theory.

    For the study, researchers at University of Michigan analyzed saliva samples from 250 first-year medical residents. The researchers examined the length of the students' telomeres, or the caps at the ends of chromosomes that protect them from DNA damage.

    "Telomeres shorten every time our cells replicate, acting as a kind of fuse at the end of DNA," Khullar writes. "Once they become too short, cells know that it's time to retire or self-destruct." The process is connected to age-related diseases, including diabetes, cancer, and heart disease, Khullar explains.

    After examining residents' telomeres before and after their first year of residency, the researchers found that first-year residents' DNA aged six times faster than normal. For instance, Khullar explains that telomeres usually shrink at an average rate of 25 DNA base-pairs per year, but the first-year medical residents' telomeres were shrinking by an average of more than 140-base pairs.

    The more hours the residents worked, the more their telomeres would shrink, according to the study. But, residents who worked more than 75 hours per week saw their telomere shrinkage "skyrocket" to more than 700 base-pairs on average, Khullar writes.

    Should residents work fewer hours?

    The medical field has long debated how much and how hard residents should work, especially as other research shows "widespread anxiety, depression, and burnout among medical trainees and physicians," Khullar writes.

    But the researchers noted that the new study adds another health concern to the existing data: "measurable physiological effects at the cellular level." Srijan Sen, senior author of the study and associate professor of psychiatry at the University of Michigan, said they hope the findings can "help catalyze residency reforms that really move the needle."

    But the "solution is not simply to reduce work hours," Khullar writes. Being a doctor requires repetition and consistent immersion so that diagnoses and treatment and surgery methods can become "muscle memory," he writes. "Most residents, some of whom are approaching 40 when they finish training, would probably balk at an offer to trade shorter hours for more years of training—even if it does cost them a little telomere," he said. 

    What matters more is "how residents work all those hours," Khullar writes. "Training programs should reduce the number of day-to-night transitions residents have to make, as these can lead to circadian rhythm disruptions and mood problems," he said, adding that residents should also be allowed more flexibility in their schedule to attend lectures, conferences, and important personal events.

    In addition, Khullar writes residency programs can take measures "to improve well-being in medical training," such as by providing healthier food for busy residents or offering structured wellness program.

    "Medical training is—and needs to be—intense," Khullar writes. "But too often our current system strains, instead of supports, trainees along their journey. That's not good for doctors or for patients" (Khullar, "Well," New York Times, 7/25).

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