New doctors’ DNA ages 6 TIMES faster than usual in their first year of residency, study finds

A doctor’s first year in residency is so intense that their DNA ages six times faster than usual, according to a new study.

Researchers took DNA samples from 250 medical students who graduated from the University of Michigan, first before starting their intern year, then again 12 months later, along with a questionnaire.

They were looking for a tell-tale sign of ageing: if the length of their telomeres – the caps on the end of chromosomes, which keep cells intact – had shrunk.

As we age, our telomeres shrink and break down, leading to weariness.

The new study found dramatic and rapid shortening of telomeres in all new residents. The longer the hours, the bigger the shrink. 

Meanwhile students in their first undergraduate year at the same school saw no changes to their DNA, despite having to adapt to a new environment and workload. 

The findings hammer home the intensity of a doctor’s first year out of school – and suggest DNA swabs could be used to monitor stress and burn-out in all professions. 

‘Research has implicated telomeres as an indicator of aging and disease risk,’ said lead author Dr Srijan Sen, a neuroscientist and psychiatrist at the University of Michigan. 

‘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.’ 

Telomere length varied at the start of the study, a factor which the questionnaires helped to explain. 

Those with stressful home environments, for example, had shorter ones, as did grads who fit the description for ‘neurotic’. 

But the only thing that influenced telomere shrinkage during their first year in residency was the amount of time they worked.  

The average work week was 64.5 hours, though many recorded working days far longer than 16 hours, which is the national limit, with some hitting 80 hours a week. 

‘We found that those who routinely worked that many hours had most telomere attrition,’ Dr Sen said. 

‘Those whose hours were at the lower end of the range had less telomere attrition.’

The findings form part of Dr Sen’s larger project: The Intern Study, which is tracking intern’s mood, sleep and lifestyle using phone apps. 

Burn-out is a growing issue in all industries, and fiercely in medicine. 

Dr Sen hopes to compile data on every aspect of work and health to begin mapping out the key issues and work on how to change them. 

In a previous study, Dr Sen showed how erratic shift patterns impacted physical and mental health, and he is now looking at how that affects telomeres.  

For now, he says, ‘Residency directors should do as much as they can to keep their interns’ work hours and work load towards the lower end of the current range.’

And as new doctors prepare to graduate and head into their intern years, he advises them to focus on their mood, sleep and stress-relieving activities as much as they can. 


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