title: Genetic and environmental contributions to the Child Behavior Checklist Obsessive-Compulsive Scale: a cross-cultural twin study.
abstract: BACKGROUND
  We have reported elsewhere on the development of an 8-item Obsessive-Compulsive Scale (OCS) contained in the Child Behavior Checklist (CBCL) to identify children who meet criteria for DSM-IV obsessive-compulsive disorder. Twin studies of obsessive-compulsive disorder have indicated a significant genetic component to its expression.
  
  
  OBJECTIVE
  To determine the relative contributions of genetic and environmental influences on childhood obsessive-compulsive behavior using the CBCL OCS in twin samples.
  
  
  METHODS
  The CBCL data were received by survey of twins in the Netherlands Twin Registry (NTR) and the Missouri Twin Study (USA/MOTWIN).
  
  
  METHODS
  General community twin samples.
  
  
  METHODS
  Participants were 4246 twin pairs aged 7 years, 2841 aged 10 years, and 1562 aged 12 years (who also participated in the study at 7 and 10 years of age) from the NTR and 1461 mixed-age twin pairs (average age, approximately 9 years) from the USA/MOTWIN.
  
  
  METHODS
  Model fitting to test for genetic and environmental influences, sex differences, and sibling interaction/rater contrast effects on the CBCL OCS.
  
  
  RESULTS
  In each case, the best-fitting model was one that indicated significant additive genetic influences (range, 45%-58%; 95% confidence interval [CI], 45%-61%), and unique environmental influences (range, 42%-55%; 95% CI, 39%-55%), with shared environmental influences in the NTR sample aged 12 years (16%). Sex differences were seen in the mixed-age USA/MOTWIN model, but not in the NTR samples. No evidence of dominance, sibling interaction, or rater-contrast effects was seen. These data were relatively consistent across age and cultures.
  
  
  CONCLUSIONS
  The CBCL OCS is influenced by genetic factors (approximately 55%) and unique environmental factors (approximately 45%) in the younger sample, with common environmental influences only at 12 years of age. These effects do not vary with differences in sex or sibling interaction/rater contrast effects. Our data reveal higher genetic influences for obsessive-compulsive behavior and do not demonstrate genetic differences across sex.
authors.affiliation: Department of Psychiatry, University of Vermont, Burlington; Vrije University, Amsterdam, The Netherlands. james.hudziak@uvm.edu
authors.forename: James J
authors.initials: JJ
authors.lastname: Hudziak
authors.forename: C E M
authors.initials: CE
authors.lastname: Van Beijsterveldt
authors.forename: Robert R
authors.initials: RR
authors.lastname: Althoff
authors.forename: Catherine
authors.initials: C
authors.lastname: Stanger
authors.forename: David C
authors.initials: DC
authors.lastname: Rettew
authors.forename: Elliot C
authors.initials: EC
authors.lastname: Nelson
authors.forename: Richard D
authors.initials: RD
authors.lastname: Todd
authors.forename: Meike
authors.initials: M
authors.lastname: Bartels
authors.forename: Dorret I
authors.initials: DI
authors.lastname: Boomsma
mesh_terms: D000367:Age Factors; D002648:Child; D003431:Cross-Cultural Comparison; D004200:Diseases in Twins / Q000175:diagnosis* / Q000235:genetics*; D005260:Female; D015870:Gene Expression; D006801:Humans; D008297:Male; D008923:Missouri; D008957:Models, Genetic; D008967:Molecular Biology; D009426:Netherlands; D009771:Obsessive-Compulsive Disorder / Q000175:diagnosis* / Q000235:genetics*; D010555:Personality Inventory / Q000706:statistics & numerical data*; D010641:Phenotype; D011569:Psychiatric Status Rating Scales / Q000706:statistics & numerical data*; D012737:Sex Factors; D012931:Social Environment; D014429:Twins, Dizygotic / Q000235:genetics; D014430:Twins, Monozygotic / Q000235:genetics; D014481:United States