Objective: We examined the prospective association between self-labeled and witness-reported bullying and the risk of newly onset of depression.
Methods: Employees were recruited from two cohorts of 3196 and 2002 employees, respectively. Participants received a questionnaire at baseline in 2006 to 2007 with follow-up in 2008 to 2009 and 2011. New cases of depression were diagnosed in the follow-up using Schedules for Clinical Assessment in Neuropsychiatry interviews and the Major Depression Inventory questionnaire.
Results: We identified 147 new cases of depression. The odds ratio for newly onset depression among participants reporting bullying occasionally was 2.17 (95% confidence interval [CI]: 1.11 to 4.23) and among frequently bullied 9.63 (95% CI: 3.42 to 27.1). There was no association between percentage witnessing bullying and newly onset depression.
Conclusions: Frequent self-labeled bullying predicts development of depression but a work environment with high proportion of employees witnessing bullying does not.