title: Methylphenidate improves response inhibition in adults with attention-deficit/hyperactivity disorder.
abstract: BACKGROUND
  Response inhibition is an executive function that requires voluntary control over responses when there is a change of context. The right inferior frontal cortex is necessary for response inhibition, and a deficit in right frontostriatal circuitry might underlie attention-deficit/hyperactivity disorder (ADHD). Many studies of childhood ADHD have demonstrated impaired response inhibition and its amelioration by methylphenidate (MPH). The current study tested response inhibition and the effect of MPH in adult ADHD.
  
  
  METHODS
  Response inhibition was assessed with the "tracking" stop-signal test in 13 adults with a diagnosis of ADHD, both while taking and while not taking medication, and 13 healthy, unmedicated, age- and intelligence quotient-matched control subjects.
  
  
  RESULTS
  Stop-signal reaction time was significantly slower in unmedicated adults with ADHD relative to healthy control subjects, and this deficit was significantly ameliorated by medication.
  
  
  CONCLUSIONS
  Adult ADHD patients had a response inhibition profile similar to that produced by lesions to the right inferior frontal cortex, which was remedied by stimulant medication.
authors.affiliation: Department of Psychiatry, University of Cambridge, Addenbrooke's Hospital, Cambridge, United Kingdom.
authors.forename: Adam R
authors.initials: AR
authors.lastname: Aron
authors.forename: Jonathon H
authors.initials: JH
authors.lastname: Dowson
authors.forename: Barbara J
authors.initials: BJ
authors.lastname: Sahakian
authors.forename: Trevor W
authors.initials: TW
authors.lastname: Robbins
mesh_terms: D000293:Adolescent; D000328:Adult; D001289:Attention Deficit Disorder with Hyperactivity / Q000188:drug therapy*; D016022:Case-Control Studies; D000697:Central Nervous System Stimulants / Q000627:therapeutic use*; D006801:Humans; D007266:Inhibition, Psychological; D007360:Intelligence / Q000187:drug effects; D007361:Intelligence Tests; D008297:Male; D008774:Methylphenidate / Q000627:therapeutic use*; D009483:Neuropsychological Tests; D011597:Psychomotor Performance / Q000187:drug effects; D011930:Reaction Time / Q000187:drug effects; D013997:Time Factors
chemical_list: D000697:Central Nervous System Stimulants; D008774:Methylphenidate