Genetic influences on the spontaneous EEG: An examination of 15‐year‐old and 17‐year‐old twins

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Abstract
In this study, the authors investigated the presence of genetic influences and development on the spontaneous electroencephalogram (EEG) by examining the similarity of 15‐ and 17‐year‐old monozygotic (MZ) and dizygotic (DZ) twins. A total of 50 (nMZ = 33, nDZ = 17) 15‐year‐old and 69 (nMZ = 45, nDZ = 24) 17‐year‐old twin pairs were assessed. Spontaneous EEG was recorded from the vertex and 2 lateral posterior sites while participants rested with eyes closed. Measures of both absolute and relative power were derived for delta, theta, alpha, and beta frequency bands. The intraclass correlations of all bands across all sites for both absolute and relative power were significant for the MZ twins, indicating moderate to high degrees of MZ similarity on these measures. All MZ intraclass correlations were larger than the corresponding DZ correlations, and they were significantly larger for over 70% of the MZ‐DZ comparisons involving the 2 age cohorts. Biometric modeling of EEG spectral data suggested a substantial genetic effect on EEG, with over 70% of 54 calculated heritability coefficients ≥ .70. This pattern of findings suggests a genetic influence on the spontaneous EEG of both middle and late adolescent children. Analysis of EEG power as a function of age revealed a significant decrease in all frequency bands across all sites from age 15 to 17. This EEG “power drop” most likely reflects the result of developmental changes in brain structure and metabolism occurring during the final stages of adolescent central nervous system maturation.