Risk factors at medical school for later severe depression: A 15-year longitudinal, nationwide study (NORDOC)

Background: Doctors have an increased risk of suicide, and depressive symptoms are prominent among young doctors. We lack prospective studies that identify risk factors to be targeted in medical schools. Methods: From 1993 to 2008, graduating medical students (n=631) from all four Norwegian universities participated in the Longitudinal Study of Norwegian Medical Students and Doctors (NORDOC). After their graduating term (T1), they were followed up 1 (T2), 4 (T3), 10 (T4), and 15 (T5) years later with postal surveys. Severe depressive symptoms were measured by the General Health Questionnaire-28 (T1, T2, T3, T4, and T5) and analyzed by generalized estimating equations. Results: At T1 and T5, 13.7% and 7.2%, respectively, of the doctors reported severe depressive symptoms; a significant reduction over time (p=0.001) in both genders (response rates 56-83%). Independent risk factors for future depressive symptoms were: young age (odds ratio [OR] 1.1, 95% confidence interval [CI] 1.04-1.2, p=0.003); high neuroticism (OR 3.4, 95% CI 1.5-7.6, p=0.003); high reality weakness (OR 2.3,95% CI 1.2-4.2, p=0.008); and severe depressive symptoms at T1 (OR 3.6,95% CI 2.1-6.1, p<0.001). Limitations: Selection bias and concurrent life and work stress may have influenced the results. Conclusions: In addition to low age, high neuroticism yielded a threefold increased risk over the 15-year follow-up, whereas high reality weakness, which is linked to personality pathology, doubled the risk. These factors are clinically relevant for identification of students at risk. (C) 2012 Elsevier B.V. All rights reserved.