Individual analysis of EEG background-activity within school age: impact of age and sex within a longitudinal data set.
OBJECTIVE
Quantitative EEG can monitor changes in brain function during development and may help to understand developmental disorders. However, current EEG-databases are primarily based on standardized frequency bands which disregard age-related changes in alpha peak frequency (PF) and therefore complicate the interpretation of spectral estimates in the theta and alpha range.


METHODS
We used a two point longitudinal design in order to analyze intraindividual changes in 40 healthy children and adolescents with age (T1: 6-18 years; interval approximately 4 years). Using a 64-channel eyes closed resting EEG we calculated absolute/relative power in individualized frequency bands (IFB: delta, theta, alpha1/2 and beta) based on PF.


RESULTS
PF increased with age, with changes being larger for children than adolescents. Controlling for changes in PF, changes in absolute/relative alpha1/2 power and in absolute beta power were minor. Relative beta power, however, increased while absolute/relative delta and theta power decreased massively. Sex-differences in PF did not reach significance. However, boys exhibited larger changes during adolescence than girls for all absolute power measures except alpha.


CONCLUSIONS
Normal EEG development during school-age is mainly based on an absolute decrease of slow frequency activity and increases of PF which may be interpreted in terms of a reorganization of the EEG towards a higher frequency oscillatory scale rather than a maturation of the theta-alpha1/2 band power sequence. Age-related changes differed between boys and girls suggesting a different developmental timing for the sexes. In future studies a combined analysis of PF and IFB may help to specify deviations in developmental disorders.
Section of Experimental Psychopathology and Neurophysiology, Department of Psychiatry, University of Heidelberg, Voss-Straße 4, 69115 Heidelberg, Germany. Dennis.Gmehlin@med.uni-heidelberg.de
Dennis
D
Gmehlin
Christine
C
Thomas
Matthias
M
Weisbrod
Stephan
S
Walther
Ute
U
Pfüller
Franz
F
Resch
Rieke
R
Oelkers-Ax
D000293:Adolescent; D000367:Age Factors; D000375:Aging / Q000502:physiology*; D001921:Brain / Q000254:growth & development* / Q000502:physiology*; D002648:Child; D016208:Databases, Factual; D004569:Electroencephalography / Q000379:methods*; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D012727:Sex Characteristics; D012737:Sex Factors