title: Deficient response inhibition as a cognitive endophenotype of ADHD.
abstract: OBJECTIVE
  To investigate whether a deficient response inhibition is a cognitive endophenotype of attention-deficit/hyperactivity disorder (ADHD). The authors hypothesized that nonaffected siblings of ADHD probands would have a response inhibition between that of ADHD probands and normal controls, although they resembled the controls at a behavioral level.
  
  
  METHODS
  Participants were 25 ADHD probands with a family history of ADHD, their nonaffected siblings (n = 25), and 48 normal controls matched for age and IQ. All participants were between 6 and 17 years of age. The nonaffected siblings were compared with their ADHD siblings and with controls on measures reflecting different types of response inhibition.
  
  
  RESULTS
  The nonaffected siblings had results similar to those of the ADHD probands, who differed from the controls on all inhibition measures (p <.05).
  
  
  CONCLUSIONS
  Siblings of ADHD probands, while not behaviorally expressing the disorder, have ADHD-associated deficits in response inhibition. This suggests that subtyping based on measures of response inhibition can help identify genetic susceptibility to ADHD. Children with a genetic vulnerability to ADHD may have hidden cognitive deficits in the absence of manifest behavioral symptoms. Therefore, they should be monitored to detect possible learning problems.
authors.affiliation: Department of Child and Adolescent Psychiatry, University Medical Center, Huispostnr: F05.126, P.O. Box 85500, 3508 GA Utrecht, The Netherlands. d.willemse@psych.azu.nl
authors.forename: Dorine
authors.initials: D
authors.lastname: Slaats-Willemse
authors.forename: Hanna
authors.initials: H
authors.lastname: Swaab-Barneveld
authors.forename: Leo
authors.initials: L
authors.lastname: de Sonneville
authors.forename: Emma
authors.initials: E
authors.lastname: van der Meulen
authors.forename: Jan
authors.initials: J
authors.lastname: Buitelaar
mesh_terms: D000293:Adolescent; D001289:Attention Deficit Disorder with Hyperactivity / Q000150:complications / Q000235:genetics* / Q000523:psychology*; D016022:Case-Control Studies; D002648:Child; D002652:Child Behavior; D003071:Cognition; D005260:Female; D020022:Genetic Predisposition to Disease; D006801:Humans; D007266:Inhibition, Psychological; D008297:Male; D010641:Phenotype