title: Age and sex effects in the EEG: differences in two subtypes of attention-deficit/hyperactivity disorder.
abstract: OBJECTIVE
  This study investigated age-related changes and sex differences in the EEGs of two groups of children with attention-deficit/hyperactivity disorder (ADHD) combined type and ADHD predominantly inattentive type, in comparison with a control group of normal children.
  
  
  METHODS
  Forty boys and forty girls were included in each group. The EEG was recorded during an eyes-closed resting condition and Fourier transformed to provide estimates for total power, absolute and relative power in the delta, theta, alpha and beta bands, and for theta/alpha and theta/beta ratios.
  
  
  RESULTS
  Total power, relative alpha, and the theta/alpha and theta/beta ratios were differentiated between all 3 groups. Sex differences between the ADHD subjects and the control group were greater in males than females and matured faster in males. With increasing age, the EEG of the ADHD inattentive group was found to change at a similar rate to the changes found in the normal group, with the differences in power levels remaining constant. In the ADHD combined group, the power was found to change at a greater rate than in the ADHD inattentive group, with power levels of the two ADHD groups becoming similar with age.
  
  
  CONCLUSIONS
  These results are supportive of a two-component model of ADHD, with the hyperactive/impulsive component maturing with age and the inattentive component remaining more stable.
authors.affiliation: Department of Psychology, University of Wollongong, Northfields Avenue, NSW 2522, Wollongong, Australia.
authors.forename: A R
authors.initials: AR
authors.lastname: Clarke
authors.forename: R J
authors.initials: RJ
authors.lastname: Barry
authors.forename: R
authors.initials: R
authors.lastname: McCarthy
authors.forename: M
authors.initials: M
authors.lastname: Selikowitz
mesh_terms: D000375:Aging / Q000502:physiology*; D000513:Alpha Rhythm; D001289:Attention Deficit Disorder with Hyperactivity / Q000145:classification / Q000503:physiopathology*; D001611:Beta Rhythm; D001921:Brain / Q000502:physiology / Q000503:physiopathology*; D002648:Child; D003700:Delta Rhythm; D005260:Female; D005583:Fourier Analysis; D007839:Functional Laterality; D006801:Humans; D007361:Intelligence Tests; D008297:Male; D012016:Reference Values; D012146:Rest; D012727:Sex Characteristics; D013826:Theta Rhythm