Genetic analysis of the resting electroencephalographic power spectrum in human twins.

Most twin studies have provided evidence for genetic effects on the electroencephalogram (EEG). In two twin studies, monozygotic (MZ) cotwin covariance for EEG power was greater than expected for additive gene actions, as compared with dizygotic (DZ) cotwin covariance. These findings were attributed to complex gene interactions, termed emergenesis. In the present study of 53 MZ and 38 DZ twin pairs departures from the additive genetic model were tested on resting EEG power. Total spectral power and the quotient of (beta band power)/(total power) both fit gene interaction models significantly better than did additive genetic models. These findings support the previous findings of MZ covariance for EEG power as much greater than DZ covariance; these findings can be explained entirely by the additive effects of genes. This pattern of twin covariances could be due to gene interactions but also to greater MZ than DZ environmental covariance.