title: Why some children with externalising problems develop internalising symptoms: testing two pathways in a genetically sensitive cohort study.
abstract: BACKGROUND
  Children with externalising problems are at risk of developing internalising problems as they grow older. The pathways underlying this developmental association remain to be elucidated. We tested two processes that could explain why some children with externalising problems develop internalising symptoms in preadolescence: a mediation model whereby the association between early externalising and later new internalising symptoms is explained by negative experiences; and a genetic model, whereby genes influence both problems.
  
  
  METHODS
  We used data from the Environmental Risk (E-Risk) Study, a 1994-1995 birth cohort of 2,232 twins born in England and Wales. We assessed externalising and internalising problems using combined mothers' and teachers' ratings at age 5 and 12. We measured bullying victimisation, maternal dissatisfaction and academic difficulties between age 7 and 10 and used linear regression analyses to test the effects of these negative experiences on the association between early externalising and later internalising problems. We employed a Cholesky decomposition to examine the genetic influences on the association.
  
  
  RESULTS
  Children with externalising problems at age 5 showed increased rates of new internalising problems at age 12 (r = .24, p < .001). Negative experiences accounted for some of the association between early externalising and later internalising problems. Behavioural-genetic analyses indicated that genes influencing early externalising problems also affected later internalising problems.
  
  
  CONCLUSIONS
  Our findings highlight the role of genetic influences in explaining why some children with externalising problems develop internalising symptoms in preadolescence. Negative experiences also contribute to the association, possibly through gene-environment interplay. Mental health professionals should monitor the development of internalising symptoms in young children with externalising problems.
authors.affiliation: MRC Social, Genetic and Developmental Psychiatry Centre, Institute of Psychiatry, Psychology & Neuroscience, King's College London, London, UK.
authors.forename: Jasmin
authors.initials: J
authors.lastname: Wertz
authors.affiliation: MRC Social, Genetic and Developmental Psychiatry Centre, Institute of Psychiatry, Psychology & Neuroscience, King's College London, London, UK.
authors.forename: Helena
authors.initials: H
authors.lastname: Zavos
authors.affiliation: MRC Social, Genetic and Developmental Psychiatry Centre, Institute of Psychiatry, Psychology & Neuroscience, King's College London, London, UK.
authors.forename: Timothy
authors.initials: T
authors.lastname: Matthews
authors.affiliation: MRC Social, Genetic and Developmental Psychiatry Centre, Institute of Psychiatry, Psychology & Neuroscience, King's College London, London, UK.
authors.forename: Kirsten
authors.initials: K
authors.lastname: Harvey
authors.affiliation: MRC Social, Genetic and Developmental Psychiatry Centre, Institute of Psychiatry, Psychology & Neuroscience, King's College London, London, UK.
authors.forename: Alice
authors.initials: A
authors.lastname: Hunt
authors.affiliation: Stress, Psychiatry and Immunology Laboratory, Institute of Psychiatry, Psychology & Neuroscience, King's College London, London, UK.
authors.forename: Carmine M
authors.initials: CM
authors.lastname: Pariante
authors.affiliation: MRC Social, Genetic and Developmental Psychiatry Centre, Institute of Psychiatry, Psychology & Neuroscience, King's College London, London, UK.
authors.forename: Louise
authors.initials: L
authors.lastname: Arseneault
mesh_terms: D000124:Achievement; D000374:Aggression / Q000523:psychology*; D001008:Anxiety Disorders / Q000235:genetics* / Q000523:psychology*; D058445:Bullying; D002648:Child; D002653:Child Behavior Disorders / Q000235:genetics* / Q000523:psychology*; D002675:Child, Preschool; D015331:Cohort Studies; D003866:Depressive Disorder / Q000235:genetics* / Q000523:psychology*; D018450:Disease Progression; D004200:Diseases in Twins / Q000235:genetics* / Q000523:psychology*; D004739:England; D059647:Gene-Environment Interaction; D006801:Humans; D007389:Internal-External Control; D007604:Juvenile Delinquency / Q000523:psychology*; D007859:Learning Disabilities / Q000235:genetics / Q000523:psychology; D008137:Longitudinal Studies; D008957:Models, Genetic; D010552:Personality Assessment; D010641:Phenotype; D000066553:Problem Behavior / Q000523:psychology*; D012307:Risk Factors
keywords: Externalising and internalising problems; development; failure model; genetic influence