title: Twin study of the relationship between adolescent attention-deficit/hyperactivity disorder and adult alcohol dependence.
abstract: OBJECTIVE
  Adolescent problem behaviors such as conduct disorder and attention-deficit/hyperactivity disorder (ADHD) are often associated with alcohol problems in adulthood, particularly alcohol dependence. This association is partly a result of shared genetic liability. However, it is unclear whether ADHD, or an ADHD subtype, shares genetic influences with alcohol dependence beyond those also shared by conduct disorder.
  
  
  METHODS
  We evaluated phenotypic associations between adolescent conduct disorder and ADHD phenotypes with adult alcohol dependence in a population-based sample of adult male twins (N = 1,774). We then assessed genetic and environmental relationships among phenotypes using structural equation modeling.
  
  
  RESULTS
  Individually, conduct disorder and each ADHD factor were associated with adult alcohol dependence. Results from twin modeling indicate that a genetic factor common to conduct disorder and ADHD also loads strongly onto alcohol dependence. Even after controlling for genetic factors shared with conduct disorder and other ADHD factors, the hyperactivity component of ADHD shared significant residual genetic influences with alcohol dependence.
  
  
  CONCLUSIONS
  Most of the genetically mediated association between adolescent ADHD and adult alcohol dependence is shared with conduct disorder, reflecting a generalized risk to externalizing behaviors. The significant residual genetic covariance between the ADHD factor hyperactivity/impulsivity and alcohol dependence implies that impulsive behaviors less destructive/harmful than those manifested by conduct disorder can be indicative of genetic risk for adult alcohol dependence. However, the ADHD factors inattention and forgetfulness are not uniquely predictive of genetic/environmental risk for alcohol dependence.
authors.affiliation: Virginia Institute for Psychiatric and Behavioral Genetics, and Department of Psychiatry, Virginia Commonwealth University, Richmond, Virginia 23298-0126, USA. aedwards5@vcu.edu
authors.forename: Alexis C
authors.initials: AC
authors.lastname: Edwards
authors.forename: Kenneth S
authors.initials: KS
authors.lastname: Kendler
mesh_terms: D000293:Adolescent; D000294:Adolescent Behavior / Q000523:psychology*; D000328:Adult; D000437:Alcoholism / Q000150:complications / Q000523:psychology*; D001289:Attention Deficit Disorder with Hyperactivity / Q000150:complications / Q000523:psychology*; D002648:Child; D019955:Conduct Disorder / Q000150:complications / Q000523:psychology; D017831:Diagnosis, Dual (Psychiatry) / Q000523:psychology / Q000706:statistics & numerical data; D004200:Diseases in Twins / Q000523:psychology*; D059647:Gene-Environment Interaction; D020022:Genetic Predisposition to Disease / Q000523:psychology; D006801:Humans; D008297:Male; D008875:Middle Aged; D008960:Models, Psychological; D010641:Phenotype; D014427:Twins / Q000523:psychology*