Effect of different factors on EEG spectral parameters.

We had previously observed that in groups of children with low socioeconomic and cultural level the EEG spectral parameters did not correlate with age due to the great variance in the distribution of such EEG parameters. In this paper we have made several statistical analyses in order to look for other factors that may explain the great variance observed. EEG during rest was recorded in 14 monopolar leads from 119 children. After FFT the following measures were calculated: absolute power, relative power, dominant frequency, coherence and left power/right power ratio for the delta, theta, alpha and beta bands in each derivation. For each measure, in each derivation, ANOVA analyses were performed taking age as covariable and sex, presence or absence of antecedents of risk factors and of learning disorders (LD) as independent variables. Age had its main effect on absolute power in the different bands and in the dominant frequency in the alpha band. Sex affected absolute and relative power in the alpha band. Risk factors per se had no effect. Presence of LD showed its main effect on absolute power. Many interactions between risk and LD and sex and LD were observed. Other analyses, such as MANCOVA, corroborated these results: significant differences between girls and boys, significant differences between children with and without LD and no differences between children with and without antecedents of risk factors.