Background Earlier studies, based on data collected among juvenile court clients or prisoners, suggest that there is an association between trauma and adolescent-onset offending. However, there is a lack of large-scale data on juvenile violence and clinical mental health observations with unselected participants, and a risk-factor-oriented research combining multiple variables affecting violent behaviour.

Methods We analyse the effect of trauma on violent offending using longitudinal register-linkage population data. The study is based on administrative data on all Finnish children born between 1986 and 2000, linked with their biological and adoptive parents (N=913 675). The data include annually updated demographic and socioeconomic information from Statistics Finland, hospital discharge and specialised outpatient service records as well as the data from all suspected criminal offences known to the police (1996–2017). We measured trauma diagnosis at age 12–14 and followed participants for subsequent violent criminality from age 15 to 17.

Results The population average estimates, taking into account observed substance abuse and other mental health diagnoses, shows that trauma-related disorders (adjustment problems, post-traumatic stress disorder and acute stress disorder) were associated with violent offending. The same was true in sibling fixed effect models, which take into account genetic and environmental confounding shared by siblings.

Discussion These results suggest that severe stress related to traumatic or strong negative life changes in adolescence is a risk factor for violent behaviour.