Age and sex effects in the EEG: development of the normal child

Objectives: This study investigated age-related changes and sex differences in the EEGs of normal children. Methods: Forty boys and 40 girls, between the ages of 8 and 12 years, parti cipated in this study. The EEG was recorded during an eyes-closed resting c ondition and Fourier transformed to provide estimates for total power, abso lute and relative power in the delta, theta, alpha and beta bands, and for theta/alpha and theta/beta ratios. Results: Absolute delta activity decreased with age. Relative delta and the ta decreased and alpha and beta increased with increasing age. The theta/al pha and theta/beta ratios decreased with increasing age. All of these indic ated a developmental reduction in slow wave activity. Maturational differen ces were found in tile rates of change between the midline and the two hemi spheres. In the absolute delta and the theta/beta ratio, the midline and th e two hemispheres became more equipotential with age. In the beta band, pow er increased at a greater rate than in the two hemispheres. Sex differences were found, with males having less theta and more alpha than females. Conclusions: These results indicated that maturation occurs earlier at the midline than in the two hemispheres. Females were also found to have a deve lopmental lag in the EEG compared with males. (C) 2001 Elsevier Science Ire land Ltd. All rights reserved.