title: Coherence in children with AD/HD and excess alpha power in their EEG.
abstract: OBJECTIVE
  This study investigated differences in EEG coherence measures between two groups of children with Attention-Deficit/Hyperactivity Disorder (AD/HD) - one with the more common EEG profile (increased theta), and a group with excess alpha activity as the dominant EEG abnormality.
  
  
  METHODS
  26 children (aged 9-13years) with AD/HD were included in each of the excess-theta and excess-alpha groups, and were age- and sex-matched with 26 control subjects. EEG was recorded from 19 electrode sites during an eyes-closed resting condition. Wave-shape coherence was calculated for eight intrahemispheric and eight interhemispheric electrode pairs, for the delta, theta, alpha and beta bands.
  
  
  RESULTS
  In comparison with the controls, the excess-theta AD/HD group had increased theta intrahemispheric coherences at short-medium inter-electrode distances. Frontally, the excess-theta AD/HD group had increased interhemispheric theta and reduced beta coherences. The excess-alpha group primarily showed increased slow wave (delta and theta) intrahemispheric coherence at short-medium inter-electrode distances, and reduced alpha coherence at longer inter-electrode distances, compared with controls. An increase in frontal interhemispheric theta coherence was also found.
  
  
  CONCLUSIONS
  These results suggest that AD/HD children with excess alpha power have an underlying connectivity dysfunction in the frontal lobes, which is found in common with other subjects with the excess-theta EEG profile. However, a number of qualitative differences exist that could be associated with other aspects of the AD/HD diagnosis. The excess-alpha group appeared to have fewer frontal-lobe abnormalities than the excess-theta AD/HD group.
  
  
  CONCLUSIONS
  This is the first study to investigate coherence in AD/HD children who have the atypical profile of increased alpha power in their EEG.
authors.affiliation: Brain & Behaviour Research Institute and School of Psychology, University of Wollongong, Wollongong 2522, Australia.
authors.forename: Joel C
authors.initials: JC
authors.lastname: Robbie
authors.affiliation: Brain & Behaviour Research Institute and School of Psychology, University of Wollongong, Wollongong 2522, Australia. Electronic address: aclarke@uow.edu.au.
authors.forename: Adam R
authors.initials: AR
authors.lastname: Clarke
authors.affiliation: Brain & Behaviour Research Institute and School of Psychology, University of Wollongong, Wollongong 2522, Australia.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Barry
authors.affiliation: Brain & Behaviour Research Institute and School of Psychology, University of Wollongong, Wollongong 2522, Australia.
authors.forename: Franca E
authors.initials: FE
authors.lastname: Dupuy
authors.affiliation: Sydney Developmental Clinic, Level 6/30 Carrington St., Sydney 2000, Australia.
authors.forename: Rory
authors.initials: R
authors.lastname: McCarthy
authors.affiliation: Sydney Developmental Clinic, Level 6/30 Carrington St., Sydney 2000, Australia.
authors.forename: Mark
authors.initials: M
authors.lastname: Selikowitz
mesh_terms: D000293:Adolescent; D000513:Alpha Rhythm / Q000502:physiology*; D001289:Attention Deficit Disorder with Hyperactivity / Q000503:physiopathology*; D001921:Brain / Q000503:physiopathology*; D002648:Child; D004569:Electroencephalography; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D008297:Male; D013826:Theta Rhythm / Q000502:physiology*
keywords: AD/HD; Alpha; Coherence; EEG