***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Background Data regarding the impact of early risk factors on later involvement in bullying are scarce . We investigated the impact of preschool behaviors , family characteristics ( socio-economic status , family breakup ) and parental mental health on  bullying and victimization at age 11 ( T1 ) and age 13.5 ( T2 ) . Methods longitudinal data from a sub sample of the TRacking Adolescents ' Individual Lives Survey ( TRAILS )  ( T1 : N = 982 ; T2 : N = 977 ) . TRAILS is a prospect i ve study of adolescent mental health in a mixed urban and rural region of the Netherl and s. At T1 parents reported on family characteristics , parental mental health and retrospectively on children 's preschool behavior at age 4 - 5 . Schoolmates reported involvement of adolescents in bullying or victimization at T1 and T2 . Results Children with preschool anxiety were less likely to be bully/victim at T1 . Children with preschool aggressiveness were more likely to be bully ( T1 ) , bully/victim ( T1 and T2 ) and victim ( T2 ) and children with good preschool motor functioning were more likely to be bully ( T1 ) and less likely to be victim ( T1 and T2 ) . Children from low socioeconomic status families were more likely be to be bully , victim , or bully/victim and less likely to be uninvolved both at T1 and T2 . Finally , children from intact two parent families were more likely to be uninvolved at T2 . Conclusion Preschool behavioral , emotional and motor problems , socioeconomic status , and family breakup are related to involvement in bullying at a later age . Prevention of bullying and its consequences can be enhanced by focusing on risk groups in early life Abstract Objectives : To establish the relation between recurrent peer victimisation and onset of  self reported symptoms of anxiety or depression in the early teen years . Design : Cohort study over two years . Setting : Secondary schools in Victoria , Australia . Participants : 2680 students surveyed twice in year 8 ( aged 13 years ) and once in year 9 . Main outcome measures : Self reported symptoms of anxiety or depression were assessed by using the computerised version of the revised clinical interview schedule .  Incident cases were students scoring ≥12 in year 9 but not previously . Prior victimisation was defined as having been bullied at either or both survey times in year 8 . Results : Prevalence of victimisation at the second survey point in year 8 was 51 % ( 95 % confidence interval 49 % to 54 % ) , and prevalence of self reported symptoms of anxiety or depression was 18 % ( 16 % to 20 % ) . The incidence of self reported symptoms of anxiety or depression in year 9 ( 7 % ) was significantly associated with victimisation reported either once ( odds ratio 1.94 , 1.1 to 3.3 ) or twice ( 2.30 , 1.2 to 4.3 ) in year 8 . After adjustment for availability of social relations and for sociodemographic factors , recurrent victimisation remained predictive of self reported symptoms of anxiety or depression for girls ( 2.60 , 1.2 to 5.5 ) but not for boys ( 1.36 , 0.6 to 3.0 ) . Newly reported victimisation in year 9 was not significantly associated with prior self report of symptoms of anxiety or depression ( 1.48 , 0.4 to 6.0 ) . Conclusion : A history of victimisation and poor social relationships predicts the onset of emotional problems in adolescents . Previous recurrent emotional problems are not significantly related to future victimisation . These findings have implication s for how seriously the occurrence of victimisation is treated and for the focus of interventions aim ed at addressing mental health issues in adolescents . What is already known on this topic Being bullied is a common experience for many young people Victimisation is related to depression and , to a lesser extent , anxiety , loneliness , and general self esteem Debate remains as to whether victimisation precedes the onset of emotional problems or whether young people with emotional problems “ invite ” victimisation What this study adds A history of victimisation predicts the onset of anxiety or depression , especially in adolescent girls Previous recurrent emotional problems are not significantly related to future victimisation Reduction in bullying in schools could have a substantial impact on the emotional wellbeing of young 
    Output:
    
Our meta-analyses do not offer evidence of PYD interventions in general having effects of public health significance in reducing  violence among young people .
Evaluations did not consistently report theories of change or implementation fidelity , so it is unclear if our meta-analyses provide evidence that the PYD theory of change is ineffective in reducing violence  among young people