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Postgraduate medical education is stressful, but does it cause clinically significant depression? In a multicenter study of 740 medical interns in 2007–2009, researchers used computer-based, self-administered quarterly questionnaires and saliva samples to examine the prevalence of depression and its relationship to genetic polymorphisms in the serotonin transporter promoter (5-HTTP). The main instrument was the nine-item Patient Health Questionnaire (PHQ-9), typically used to screen primary-care patients for depression. Researchers also obtained information on demographics, neuroticism, resilience, perceived stress, social and family factors, and cognitive style.
The mean PHQ-9 score was 2.38 at baseline, as high as 6.70 during internship, and 6.26 at end of internship. The PHQ-9 criterion for major depression (score, ≥10) was met by 4% of interns at baseline and a mean of 25% during internship; 42% met this criterion at least once. Few interns (2.3% during internship) met the PHQ-9 criterion for severe depression (score, ≥20). Prevalence of all nine items, including sleeping difficulties and thoughts of death, increased significantly. Several baseline factors (past depression, lower initial PHQ-9 scores, female sex, neuroticism, difficult early family environment, and U.S. medical education) and within-internship factors (work hours, perceived medical errors, and outside stressful events) predicted increases in PHQ-9 scores. In whites, having one short 5-HTTP allele was associated with a greater increase in scores than having two long alleles.
Sen S et al. A prospective cohort study investigating factors associated with depression during medical internship. Arch Gen Psychiatry 2010 Jun; 67:557.
Kendler KS. The stress of internship and interactions with stress. Arch Gen Psychiatry 2010 Jun; 67:566.
Comment
Some commentators might argue that these results justify further decreases in interns' hours to reduce depression and medical errors. However, the PHQ-9 was not designed for diagnosis, especially not in physicians; the endorsed items typically increase during internship (fatigue from being on call; thoughts of death from contact with dying patients); and symptoms might go away spontaneously. As an editorialist notes, long hours are not correlated with depression, but lack of control may contribute to feeling depressed. Some experts believe that many residents experience burnout, whereas other experts believe that such symptoms are developmental.
Study weaknesses include multiple hypotheses, uncorrected multiple post hoc comparisons, and lack of power in the genetics substudy. Perhaps the most relevant conclusion is that interns, and all physicians, should be taught to ameliorate common depressive feelings or distress (by helping each other and dealing with stress, bad outcomes, and worries about medical errors) and to use good clinical assessments to avoid overdiagnosis.