title: Electrophysiological indices of abnormal error-processing in adolescents with attention deficit hyperactivity disorder (ADHD).
abstract: BACKGROUND
  Impaired cognitive control has been frequently observed in children and young people with attention deficit hyperactivity disorder (ADHD) and might underlie the excessive hyperactivity and impulsivity in this population. We investigated behavioural and electrophysiological indices relevant to one domain of cognitive control; namely error processing.
  
  
  METHODS
  Adolescents aged 14 to 17 with ADHD (n = 23) and a typically developing control group (HC; n = 19) performed a visual go/no-go task. Electro-encephalography (EEG) data were collected simultaneously and response-locked error trials were averaged to derive two event-related potentials, the error-related negativity (ERN) and error positivity (Pe). Evoked theta power and inter-trial phase coherence (ITC) were measured in two time windows ('early' and 'late') equivalent to those used for detection of the ERN and Pe.
  
  
  RESULTS
  Analysis revealed normal ERN amplitude and a statistical trend for smaller Pe amplitude at a fronto-central electrode site in the ADHD group. The group also showed significant reductions in late evoked theta power and early and late theta ITC. Relationships between behavioural measures and ITC were different between groups, particularly for post-error slowing, a measure of strategic response adjustment on trials immediately following an error.
  
  
  CONCLUSIONS
  The results reveal abnormalities in behavioural and electrophysiological indices of error processing in adolescents with ADHD and suggest that ITC is more sensitive than traditional ERP measures to error-processing abnormalities.
authors.affiliation: Developmental Psychiatry, University of Nottingham, UK. maddie.groom@nottingham.ac.uk
authors.forename: Madeleine J
authors.initials: MJ
authors.lastname: Groom
authors.forename: John D
authors.initials: JD
authors.lastname: Cahill
authors.forename: Alan T
authors.initials: AT
authors.lastname: Bates
authors.forename: Georgina M
authors.initials: GM
authors.lastname: Jackson
authors.forename: Timothy G
authors.initials: TG
authors.lastname: Calton
authors.forename: Peter F
authors.initials: PF
authors.lastname: Liddle
authors.forename: Chris
authors.initials: C
authors.lastname: Hollis
mesh_terms: D000293:Adolescent; D001289:Attention Deficit Disorder with Hyperactivity / Q000175:diagnosis / Q000453:epidemiology* / Q000503:physiopathology*; D001921:Brain / Q000503:physiopathology*; D003072:Cognition Disorders / Q000175:diagnosis / Q000453:epidemiology* / Q000503:physiopathology*; D004569:Electroencephalography; D005071:Evoked Potentials / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D009483:Neuropsychological Tests; D012720:Severity of Illness Index; D013826:Theta Rhythm; D055815:Young Adult