title: Genetic and Environmental Influences on the Developmental Course of Attention-Deficit/Hyperactivity Disorder Symptoms From Childhood to Adolescence.
abstract: OBJECTIVE
  Attention-deficit/hyperactivity disorder (ADHD) is conceptualized as a neurodevelopmental disorder that is strongly heritable. However, to our knowledge, no study to date has examined the genetic and environmental influences explaining interindividual differences in the developmental course of ADHD symptoms from childhood to adolescence (ie, systematic decreases or increases with age). The reason ADHD symptoms persist in some children but decline in others is an important concern, with implications for prognosis and interventions.
  
  
  OBJECTIVE
  To assess the proportional impact of genes and the environment on interindividual differences in the developmental course of ADHD symptom domains of hyperactivity/impulsivity and inattention between ages 8 and 16 years.
  
  
  METHODS
  A prospective sample of 8395 twin pairs from the Twins Early Development Study, recruited from population records of births in England and Wales between January 1, 1994, and December 31, 1996. Data collection at age 8 years took place between November 2002 and November 2004; data collection at age 16 years took place between February 2011 and January 2013.
  
  
  METHODS
  Both DSM-IV ADHD symptom subscales were rated 4 times by participants' mothers.
  
  
  RESULTS
  Estimates from latent growth curve models indicated that the developmental course of hyperactivity/impulsivity symptoms followed a sharp linear decrease (mean score of 6.0 at age 8 years to 2.9 at age 16 years). Interindividual differences in the linear change in hyperactivity/impulsivity were under strong additive genetic influences (81%; 95% CI, 73%-88%). More than half of the genetic variation was specific to the developmental course and not shared with the baseline level of hyperactivity/impulsivity. The linear decrease in inattention symptoms was less pronounced (mean score of 5.8 at age 8 years to 4.9 at age 16 years). Nonadditive genetic influences accounted for a substantial amount of variation in the developmental course of inattention symptoms (54%; 95% CI, 8%-76%), with more than half being specific to the developmental course.
  
  
  CONCLUSIONS
  The large genetic influences on the developmental course of ADHD symptoms are mostly specific and independent of those that account for variation in the baseline level of symptoms. Different sets of genes may be associated with the developmental course vs the baseline level of ADHD symptoms and explain why some children remit from ADHD, whereas others persist. Recent longitudinal imaging data indicate that the maintenance or increase in symptoms is underpinned by atypical trajectories of cortical development. This may reflect a specific genetic liability, distinct from that which contributes to baseline ADHD symptoms, and warrants closer follow-up.
authors.affiliation: Department of Psychology, Division of Psychology and Language Sciences, University College London, London, England2MRC Social, Genetic, and Developmental Psychiatry Centre, Institute of Psychiatry, King's College London, London, England.
authors.forename: Jean-Baptiste
authors.initials: JB
authors.lastname: Pingault
authors.affiliation: Department of Psychology, Division of Psychology and Language Sciences, University College London, London, England2MRC Social, Genetic, and Developmental Psychiatry Centre, Institute of Psychiatry, King's College London, London, England.
authors.forename: Essi
authors.initials: E
authors.lastname: Viding
authors.affiliation: Department of Child and Adolescent Psychiatry, Charles Perrens Hospital and INSERM, The Bordeaux School of Public Health (Institut de Santé Publique, d'Epidémiologie et de Développement), Centre INSERM U897, Epidemiology-Biostatistics, University of Borde.
authors.forename: Cédric
authors.initials: C
authors.lastname: Galéra
authors.affiliation: MRC Social, Genetic, and Developmental Psychiatry Centre, Institute of Psychiatry, King's College London, London, England4Department of Cognitive Neuroscience, Donders Institute for Brain, Cognition, and Behaviour, Radboud University Medical Center, Nijme.
authors.forename: Corina U
authors.initials: CU
authors.lastname: Greven
authors.affiliation: Department of Psychology, Simon Fraser University, Burnaby, British Columbia, Canada.
authors.forename: Yao
authors.initials: Y
authors.lastname: Zheng
authors.affiliation: MRC Social, Genetic, and Developmental Psychiatry Centre, Institute of Psychiatry, King's College London, London, England.
authors.forename: Robert
authors.initials: R
authors.lastname: Plomin
authors.affiliation: MRC Social, Genetic, and Developmental Psychiatry Centre, Institute of Psychiatry, King's College London, London, England.
authors.forename: Frühling
authors.initials: F
authors.lastname: Rijsdijk
mesh_terms: D000293:Adolescent; D041923:Adolescent Development; D001288:Attention; D001289:Attention Deficit Disorder with Hyperactivity / Q000235:genetics* / Q000523:psychology; D002648:Child; D002657:Child Development; D004739:England; D004777:Environment; D005260:Female; D059647:Gene-Environment Interaction; D020022:Genetic Predisposition to Disease; D006801:Humans; D007175:Impulsive Behavior; D008297:Male; D011446:Prospective Studies; D014429:Twins, Dizygotic / Q000235:genetics* / Q000523:psychology; D014430:Twins, Monozygotic / Q000235:genetics* / Q000523:psychology; D014852:Wales