Correlation between spectral EEG parameters and intelligence test variables in school-age children

Objectives: The objective of the study was to investigate the relationship between the degree of intelligence and spectral electroencephalographic (EEG) parameters and to find out which EEG variables are relevant for this correlation. Methods: Bipolar 1 min EEG recordings were derived for the fronto-central and parieto-occipital leads from 155 clinically healthy 10-year-old children in vigilance state awake with eyes closed. Relative spectral power parameters were calculated by Fast Fourier Transform. Two-group t tests according to the score values of the ‘WISC-R’ intelligence test as well as univariate and multiple correlation analyses between spectral and intelligence test variables were carried out. Results: A statistically significant positive correlation of the intelligence test variables with the spectral alpha power and a significant negative correlation with the spectral power of lower frequency bands was observed. Predicting the spectral parameters by means of intelligence test variables, significant multiple correlation coefficients were revealed in the frequency ranges: 0.5–1.5, 3.0–5.0 and 9.0–10.5 Hz. The highest significance (P<0.0001) was found for the spectral value at 9.0 Hz. Conclusions: The results of t tests and correlation analyses confirm the strong relationship between spectral EEG parameters and the degree of intelligence indicating that the ‘EEG recordings do reflect intellectual abilities’. It may be supposed that the amount of the intelligence quotient is correlated with the degree of EEG maturation and thus reflects the active number of synapses and the degree of differentiation of the neuronal controlling system.