Exposure to bullying at school and depression in adulthood: A study of Danish men born in 1953

Background: Bullying among children is associated with high symptom load and depression. There is little knowledge about long-term consequences of bullying. The aim of the present study is to examine the association between recall of bullying at school and depression in midlife controlling for adult social class and parents' mental health. Methods: The analyses were based on the 2004 survey among men from the Metropolit 1953 Danish Male Birth Cohort (n = 6094). Information on depression was retrieved by the Major Depression Inventory (MDI) (prevalent depression) and by a measure of first doctor diagnosed depression between the ages 31-51 years (DD). Information on bullying was based on a recall measure of bullying in school categorized into three dimensions: occurrence; intensity; and duration. Results: Compared to subjects who had never been bullied, those exposed to bullying in school were at a significantly increased risk of having been diagnosed with depression between the ages 31-51 years. Long duration and high intensity of bullying were risk factors for both MDI and DD. Inclusion of the possible confounders (SES, parental mental illness) attenuated the associations somewhat, but the associations remained statistically significant. Conclusion: The present comparisons of the long-term incidence of depression among middle-aged men who experienced high and low levels of bullying at school might indicate that being bullied at school is a contributing factor in the development of depression. Prospective longitudinal studies are needed to confirm the effect of bullying in school on adult depression.