title: Increased response-time variability across different cognitive tasks in children with ADHD.
abstract: OBJECTIVE
  Increased response-time (RT) fluctuations below 0.2 Hz have been reported as characteristic of ADHD in some but not all studies, possibly due to methodological differences. Accordingly, We contrasted two tasks and two analytical approaches in the same sample of children with ADHD.
  
  
  METHODS
  Fifty-two children with ADHD and 49 typically developing children completed an Eriksen Flanker Task and a fixed-sequence version of the sustained attention to response task. RT fluctuations with two different frequency analyses were examined.
  
  
  RESULTS
  Robust ADHD-related increases of slow RT fluctuations within all frequencies were found in both tasks. Tasks were significantly correlated in both groups for frequencies above 0.07 Hz. RT fluctuations across all frequencies were greatest in children with ADHD with abnormally elevated omissions.
  
  
  CONCLUSIONS
  We observed significantly increased fluctuations of RT in children with ADHD across two different tasks and methods supporting the hypothesis that slow frequency RT fluctuations reflect neurophysiological processes underlying ADHD.
authors.affiliation: Institute for Pediatric Neuroscience, NYU Child Study Center, NY, USA.
authors.forename: Nicoletta
authors.initials: N
authors.lastname: Adamo
authors.affiliation: Institute for Pediatric Neuroscience, NYU Child Study Center, NY, USA Adriana.Dimartino@nyumc.org.
authors.forename: Adriana
authors.initials: A
authors.lastname: Di Martino
authors.affiliation: Child Neuropsychiatry, University of Cagliari, Cagliari, Italy.
authors.forename: Lidia
authors.initials: L
authors.lastname: Esu
authors.affiliation: Division of Biostatistics, NYU Child Study Center, New York, USA Nathan Kline Institute for Psychiatric Research, Orangeburg, NY, USA.
authors.forename: Eva
authors.initials: E
authors.lastname: Petkova
authors.affiliation: Psychological Sciences, University of Melbourne, Victoria, Australia.
authors.forename: Katherine
authors.initials: K
authors.lastname: Johnson
authors.affiliation: Department of Biomedical Engineering, City College of New York, NY, USA.
authors.forename: Simon
authors.initials: S
authors.lastname: Kelly
authors.affiliation: Institute for Pediatric Neuroscience, NYU Child Study Center, NY, USA Nathan Kline Institute for Psychiatric Research, Orangeburg, NY, USA.
authors.forename: Francisco Xavier
authors.initials: FX
authors.lastname: Castellanos
authors.affiliation: Child Neuropsychiatry, University of Cagliari, Cagliari, Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Zuddas
mesh_terms: D001288:Attention / Q000502:physiology; D001289:Attention Deficit Disorder with Hyperactivity / Q000150:complications* / Q000523:psychology; D016022:Case-Control Studies; D002648:Child; D003071:Cognition / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D009483:Neuropsychological Tests; D011597:Psychomotor Performance / Q000502:physiology; D011930:Reaction Time / Q000502:physiology*