title: Genetic and environmental influences on obsessive-compulsive behaviour across development: a longitudinal twin study.
abstract: BACKGROUND
  Little is known about the factors influencing the stability of obsessive-compulsive behaviour (OCB) from childhood to adolescence. The current study aimed to investigate: (1) the stability of paediatric OCB over a 12-year period; (2) the extent to which genetic and environmental factors influence stability; and (3) the extent to which these influences are stable or dynamic across development.
  
  
  METHODS
  The sample included 14 743 twins from a population-based study. Parental ratings of severity of OCB were collected at ages 4, 7, 9 and 16 years.
  
  
  RESULTS
  OCB was found to be moderately stable over time. The genetic influence on OCB at each age was moderate, with significant effects also of non-shared environment. Genetic factors exerted a substantial influence on OCB persistence, explaining 59-80% of the stability over time. The results indicated genetic continuity, whereby genetic influences at each age continue to affect the expression of OCB at subsequent ages. However, we also found evidence for genetic attenuation in that genetic influences at one age decline in their influence over time, and genetic innovation whereby new genes 'come on line' at each age. Non-shared environment influenced stability of OCB to a lesser extent and effects were largely unique to each age and displayed negligible influences on OCB at later time points.
  
  
  CONCLUSIONS
  OCB appears to be moderately stable across development, and stability is largely driven by genetic factors. However, the genetic effects are not entirely constant, but rather the genetic influence on OCB appears to be a developmentally dynamic process.
authors.affiliation: King's College London,MRC Social,Genetic and Developmental Psychiatry Centre,Institute of Psychiatry, Psychology and Neuroscience,De Crespigny Park,London,UK.
authors.forename: G
authors.initials: G
authors.lastname: Krebs
authors.affiliation: King's College London,MRC Social,Genetic and Developmental Psychiatry Centre,Institute of Psychiatry, Psychology and Neuroscience,De Crespigny Park,London,UK.
authors.forename: M A
authors.initials: MA
authors.lastname: Waszczuk
authors.affiliation: King's College London,MRC Social,Genetic and Developmental Psychiatry Centre,Institute of Psychiatry, Psychology and Neuroscience,De Crespigny Park,London,UK.
authors.forename: H M S
authors.initials: HM
authors.lastname: Zavos
authors.affiliation: King's College London,Department of Psychology,Institute of Psychiatry, Psychology and Neuroscience,De Crespigny Park,London,UK.
authors.forename: D
authors.initials: D
authors.lastname: Bolton
authors.affiliation: King's College London,MRC Social,Genetic and Developmental Psychiatry Centre,Institute of Psychiatry, Psychology and Neuroscience,De Crespigny Park,London,UK.
authors.forename: T C
authors.initials: TC
authors.lastname: Eley
mesh_terms: D000293:Adolescent; D041923:Adolescent Development / Q000502:physiology*; D002648:Child; D002657:Child Development / Q000502:physiology*; D002675:Child, Preschool; D004200:Diseases in Twins / Q000453:epidemiology / Q000209:etiology / Q000235:genetics*; D004739:England / Q000453:epidemiology; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D009771:Obsessive-Compulsive Disorder / Q000453:epidemiology / Q000209:etiology / Q000235:genetics*; D012720:Severity of Illness Index; D014852:Wales / Q000453:epidemiology
keywords: twins