Objective: This study investigated intra-hemispheric and inter-hemispheric EEG coherences as a function of age in boys with different subtypes of Attention Deficit/Hyperactivity Disorder (AD/HD), in comparison with a control group of normal boys.
Methods: Three groups of 40 children (AD/HD combined type, AD/HD inattentive type, and normal controls) participated. Each group contained 8 males in each 1 year band from 8 to 12 years. EEG was recorded from 21 sites during an eyes-closed resting condition. Wave-shape coherence was calculated for 8 intra-hemispheric electrode pairs (4 in each hemisphere), and 8 inter-hemispheric electrode pairs, within each of the delta, theta, alpha and beta bands.
Results: Developmental effects in intra-hemispheric coherences at shorter and longer inter-electrode distances generally supported Thatcher's two-compartment model. Control boys showed evidence of development in longer-range inter-hemispheric coherences which was not apparent in AD/HD boys. Boys with AD/HD of the combined type showed qualitatively different anomalies than boys with AD/HD of the inattentive type.
Conclusions: EEG coherences in normal boys of this age range develop systematically with age in a non-linear fashion. Boys with AD/HD do not show this development. They display coherence anomalies which differ in nature between DSM-IV subtypes, suggesting differences which are not relatable to simple symptom severity.
Significance: The data reported here indicate differences in the development of EEG coherences in boys with AD/HD, and point to differences between the AD/HD subtypes which may help understanding of the disorder.