Thousands of new doctors will begin the most intense year of their training in a few weeks, this being their first year of residency aka the intern year. Between now and this time next year this experience will make their DNA age 6 times faster than normal, and this affect will be the greatest among those with training programs that demand the most hours, according to findings.
250 interns from across the nation who volunteered for the Intern Health Study based at the University of Michigan and a comparison group of college students were involved in this study, which has implication for other professions and situations that expose people to prolonged stress and months of long hours, in the first study to measure telomere length before and after individuals faced a common prolonged intense experience of residency.
“Research has implicated telomeres as an indicator of aging and disease risk, but these longitudinal findings advance the possibility that telomere length can serve as a biomarker that tracks effects of stress, and helps us understand how stress gets ‘under the skin’ and increases our risk for disease,” says Srijan Sen, M.D., Ph.D., U-M neuroscientist and psychiatrist, who adds, “It will be important to study how telomere changes play out in larger groups of medical trainees, and in other groups of people subjected to specific prolonged stresses such as military training, graduate studies in the sciences and law, working for startup companies, or pregnancy and the first months of parenting.”
“The current model of intern year training during residency increases trainee stress, which impacts their mental health and wellbeing. These results extend this work and are the first to show that this stress reaches down to the biological level, impacting the well accepted marker of aging and disease risk, telomere length. I was particularly surprised to see the relation of number of hours worked to telomere shortening.” says Kathryn Ridout, M.D., Ph.D.
Data was analyzed from dozens of telomere studies from a published meta analysis that showed clear links between telomere length and risk and severity of depression. After which this study began by asking recently graduated medical students to contribute a sample of their DNA before and after their intern year, as well as lengthy questionnaires before they started the year and at several points during and at the end of their first year of residency.
According to the researchers results showed that some of the new doctors who went into residency had telomeres that were already shorter than their peers, these included those who reported their family environment early in life being stressful. Those scoring high on personality traits classed as neuroticism also had shorter telomeres at the start of the intern year.
DNA testing at the end of the year only had one factor that emerged with a clear link to telomere shrinkage, which was the number of hours worked each week. On average the interns worked 64.5 hours a week; the more they worked and the more days they put in that were at or above the national limit of 16 hours in effect time the faster their telomeres shrank.
“The responses given by some of the interns in these surveys indicated that some were averaging more than 80 hours of work a week, and we found that those who routinely worked that many hours had most telomere attrition. Those whose hours were at the lower end of the range had less telomere attrition.” explains Sen.
The comparison group of 84 first year undergraduate students didn’t experience any telomere shrinkage despite it also being a stressful year of coping with life and situations to obtain elite higher education.
The Intern Health Study has been collecting other DNA samples from more interns, monitoring moods, sleep habits, activity using smartphone apps, and commercial activity trackers with hopes to further study telomeres in future groups of interns to gather more information about how telomeres change over the intern year and how these changes match up with experiences during that first year such as changes in shift time.
The team also hopes to evaluate whether any practices could help to protect telomeres from shrinking or spur repair and/or lengthening. “Residency directors should do as much as they can to keep their interns’ work hours and workload towards the lower end of the current range.”
“Having completed residency myself and understanding the stress that can come with this training and extended work hours, I am hopeful this data can help inform the decisions of governing bodies that have been debating the importance of regulating resident work hours. Our results suggest that reforms in intern training and work hours with a renewed focus on wellbeing is necessary to protect the health and viability of our physician workforce.”
Those in their first intern year are advised by the researchers to keep focussed on their moods, to ensure they get enough sleep, and manage their stress with stress relieving activities as much as they can.
