title: Phenotypic and genetic associations between reading comprehension, decoding skills, and ADHD dimensions: evidence from two population-based studies.
abstract: BACKGROUND
  The phenotypic and genetic associations between decoding skills and ADHD dimensions have been documented but less is known about the association with reading comprehension. The aim of the study is to document the phenotypic and genetic associations between reading comprehension and ADHD dimensions of inattention and hyperactivity/impulsivity in early schooling and compare them to those with decoding skills.
  
  
  METHODS
  Data were collected in two population-based samples of twins (Quebec Newborn Twin Study - QNTS) and singletons (Quebec Longitudinal Study of Child Development - QLSCD) totaling ≈ 2300 children. Reading was assessed with normed measures in second or third grade. Teachers assessed ADHD dimensions in kindergarten and first grade.
  
  
  RESULTS
  Both decoding and reading comprehension were correlated with ADHD dimensions in a similar way: associations with inattention remained after controlling for the other ADHD dimension, behavior disorder symptoms and nonverbal abilities, whereas associations with hyperactivity/impulsivity did not. Genetic modeling showed that decoding and comprehension largely shared the same genetic etiology at this age and that their associations with inattention were mostly explained by shared genetic influences.
  
  
  CONCLUSIONS
  Both reading comprehension and decoding are uniquely associated with inattention through a shared genetic etiology.
authors: Research Unit on Children's Psychosocial Maladjustment, Quebec City, Canada.|Université Laval, Quebec City, Canada.
authors: Vickie
authors: V
authors: Plourde
authors: Research Unit on Children's Psychosocial Maladjustment, Quebec City, Canada.|Université Laval, Quebec City, Canada.|Institute of Genetic, Neurobiological, and Social Foundations of Child Development, Tomsk State University, Tomsk, Russia.
authors: Michel
authors: M
authors: Boivin
authors: Research Unit on Children's Psychosocial Maladjustment, Quebec City, Canada.|Université Laval, Quebec City, Canada.
authors: Nadine
authors: N
authors: Forget-Dubois
authors: Research Unit on Children's Psychosocial Maladjustment, Quebec City, Canada.|Université du Québec à Montréal, Montreal, Canada.|Sainte-Justine Hospital Research Center, Montreal, Canada.
authors: Mara
authors: M
authors: Brendgen
authors: Research Unit on Children's Psychosocial Maladjustment, Quebec City, Canada.|Sainte-Justine Hospital Research Center, Montreal, Canada.|Université de Montréal, Montreal, Canada.
authors: Frank
authors: F
authors: Vitaro
authors: Université Laval, Quebec City, Canada.|Centre de Recherche de l'Institut Universitaire en Santé Mentale de Québec, Quebec City, Canada.|Scientific Institute Eugenio Medea, Bosisio Parini, Lecco, Italy.
authors: Cecilia
authors: C
authors: Marino
authors: Research Unit on Children's Psychosocial Maladjustment, Quebec City, Canada.|Institute of Genetic, Neurobiological, and Social Foundations of Child Development, Tomsk State University, Tomsk, Russia.|Sainte-Justine Hospital Research Center, Montreal, Canada.|School of Public Health and Population Sciences, University College Dublin, Dublin, Ireland.
authors: Richard T
authors: RT
authors: Tremblay
authors: Research Unit on Children's Psychosocial Maladjustment, Quebec City, Canada.|Université Laval, Quebec City, Canada.
authors: Ginette
authors: G
authors: Dionne
mesh_terms: D001289:Attention Deficit Disorder with Hyperactivity / Q000235:genetics* / Q000503:physiopathology*; D002648:Child; D002675:Child, Preschool; D032882:Comprehension / Q000502:physiology*; D004200:Diseases in Twins; D005260:Female; D006801:Humans; D008297:Male; D010641:Phenotype; D011792:Quebec; D011932:Reading; D013067:Speech Perception / Q000235:genetics / Q000502:physiology*
keywords: Reading; comprehension; decoding; hyperactivity/impulsivity; inattention; population-based studies