Bullying refers to repeated and prolonged aggressive behaviours that are intentionally targeted

towards one or more weaker individuals. Victims may be persecuted through direct physical violence or

through indirectly harming social relationships. The prevalence of victimisation of children ranges from

approx. 10-25% across European countries. Victimisation is a powerful environmental stressor and adversely

related to concurrent children's well-being and mental health. Individual factors related to increased risk for

victimisation, however, are poorly understood: prospective studies are still rare and the mechanisms of how

genetic and family factors predict peer victimisation, and how victimisation relates to serious mental health

problems, are poorly studied.

It is proposed to investigate how family factors contribute to the development of bullying

victimisation in childhood and how environmental exposure to victimisation leads to common and severe

mental health problems in adolescence and early adulthood. The aetiology will be studied in four established

longitudinal cohort or panel studies in the UK and Germany. Study of the potential precursors of bullying

and mechanisms leading to serious mental health outcomes will include assessment of environmental and

genetic factors and experimental studies of bias in cognitive processing and effects on brain activation. The

study is highly cost-effective, utilising existing datasets, and ground-breaking in so far as it tests suspected

mechanisms in controlled studies. Understanding of the factors in families that increase the risk of

victimisation and their consequences will help to develop early interventions. Identification of malleable

environmental mechanisms will enable educators and clinicians to promote resilience and reduce the risk of

vulnerable children developing disabling and potentially life-long mental health problems. Ultimately, this

project intends to improve well-being across the life-span.