title: Maltreatment-associated neurodevelopmental disorders: a co-twin control analysis.
abstract: BACKGROUND
  Childhood maltreatment (CM) is strongly associated with psychiatric disorders in childhood and adulthood. Previous findings suggest that the association between CM and psychiatric disorders is partly causal and partly due to familial confounding, but few studies have investigated the mechanisms behind the association between CM and neurodevelopmental disorders (NDDs). Our objective was to determine whether maltreated children have an elevated number of NDDs and whether CM is a risk factor for an increased NDD 'load' and increased NDD symptoms when controlling for familial effects.
  
  
  METHODS
  We used a cross-sectional sample from a population-representative Swedish twin study, comprising 8,192 nine-year-old twins born in Sweden between 1997 and 2005. CM was defined as parent-reported exposure to emotional abuse/neglect, physical neglect, physical abuse, and/or sexual abuse. Four NDDs were measured with the Autism-Tics, AD/HD, and other comorbidities inventory.
  
  
  RESULTS
  Maltreated children had a greater mean number of NDDs than nonmaltreated children. In a co-twin control design, CM-discordant monozygotic twins did not differ significantly for their number of NDDs, suggesting that CM is not associated with an increased load of NDDs when genetic and shared environmental factors are taken into account. However, CM was associated with a small increase in symptoms of attention-deficit/hyperactivity disorder and autism spectrum disorder in CM-discordant MZ twins, although most of the covariance of CM with NDD symptoms was explained by common genetic effects.
  
  
  CONCLUSIONS
  Maltreated children are at higher risk of having multiple NDDs. Our findings are, however, not consistent with the notion that CM causes the increased NDD load in maltreated children. Maltreated children should receive a full neurodevelopmental assessment, and clinicians should be aware that children with multiple NDDs are at higher risk of maltreatment.
authors.affiliation: Gillberg Neuropsychiatry Centre, University of Gothenburg, Gothenburg, Sweden.
authors.forename: Lisa
authors.initials: L
authors.lastname: Dinkler
authors.affiliation: Gillberg Neuropsychiatry Centre, University of Gothenburg, Gothenburg, Sweden.|Centre for Ethics, Law and Mental Health (CELAM), University of Gothenburg, Gothenburg, Sweden.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Lundström
authors.affiliation: Institute of Health and Wellbeing, University of Glasgow, Glasgow, UK.
authors.forename: Ruchika
authors.initials: R
authors.lastname: Gajwani
authors.affiliation: Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Paul
authors.initials: P
authors.lastname: Lichtenstein
authors.affiliation: Gillberg Neuropsychiatry Centre, University of Gothenburg, Gothenburg, Sweden.|Institute of Health and Wellbeing, University of Glasgow, Glasgow, UK.
authors.forename: Christopher
authors.initials: C
authors.lastname: Gillberg
authors.affiliation: Gillberg Neuropsychiatry Centre, University of Gothenburg, Gothenburg, Sweden.|Institute of Health and Wellbeing, University of Glasgow, Glasgow, UK.
authors.forename: Helen
authors.initials: H
authors.lastname: Minnis
mesh_terms: D001289:Attention Deficit Disorder with Hyperactivity / Q000453:epidemiology / Q000235:genetics; D000067877:Autism Spectrum Disorder / Q000453:epidemiology / Q000235:genetics; D002648:Child; D002649:Child Abuse / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D008297:Male; D065886:Neurodevelopmental Disorders / Q000453:epidemiology* / Q000235:genetics; D012307:Risk Factors; D013548:Sweden / Q000453:epidemiology; D014427:Twins / Q000706:statistics & numerical data*
keywords: Child maltreatment; behavior genetics; child abuse; co-twin control design; neurodevelopmental disorders