Lifespan Trajectories of Resting State Bipolar EEG Power

Abstract

Normative trajectories of resting state bipolar EEG power over the lifespan were derived from a sample of 5781 participants from the Collaborative Study on the Genetics of Alcoholism (COGA), a large multi site study, using 12,906 observations from ages 12 through 70. Trajectories were analyzed using the means, variances, and correlations of data in seven frequency bands (from low theta to high beta) and 24 bipolar channels obtained from 17 electrodes of the 10-20 system. In order to make the study more useful for understanding EEG in the general population, only subjects never having an alcohol use disorder (AUD) diagnosis were included in the study. Bipolar EEG data is derived from the differencing of the signals in adjacent electrodes, either in a lateral (left-right) or sagittal (anterior-posterior) orientation; each difference is called a channel. The power values for the individual observations were calculated by standard Fourier transform based methods. In all cases there are sharp decreases in EEG power from ages 12 to the early 20s after which there are number of divergent patterns: general increases in the beta frequencies, and mixed patterns of increase and subsequent decrease in the theta and alpha frequencies. In these characteristics the lifespan trajectories presented here are similar to the monopolar trajectories described in our previous study \citet{Cho2026}. Sagittal and lateral bipolar trajectories are similar within each sex and between sexes; the primary difference is the much lower degree of regional difference in the sagittal trajectories as compared to the lateral trajectories. The pairwise inter-frequency (within channel) correlation trajectories between the four theta and alpha frequency bands and the four high alpha and beta frequency bands at each channel show striking sex differences unlike the corresponding monopolar correlations. There are a number of features in the bipolar power trajectories that suggest that the differencing procedure reduces not only local phase synchrony, but also effects of global and regional phase synchrony present in the monopolar data from which the bipolar signals are derived. The inter-frequency correlations at the individual channels are much higher in the bipolar data than the monopolar data, suggesting that global and regional phase synchrony components retained in the monopolar data have greater frequency specificity than the more purely local components in the bipolar data. Further analyses to examine many other features of the data will be undertaken in our subsequent work.