EEG recording and processing have been detailed previously [48]. Briefly, resting (eyes-closed) EEG was recorded for 4.25 min; a continuous interval of 256 s was analyzed. Conventional Fourier transform methods [49] were used to calculate coherence, and bipolar electrode pairs were derived to reduce volume conduction effects. Posterior interhemispheric (P4-O2--P3-O1) alpha band (7–12 Hz) coherence was used in the current analyses based on prior studies demonstrating the relationship with AUD [28–31]. Posterior alpha coherence was measured at least once since the start of COGA data collection on 75.7% of the analytic subsample. For individuals who had more than one EEG assessment, their most recent assessment was used. Among the analytic sample (N: 1250), those with EEG data and those without EEG data were similar in terms of frequency of women, Black and Hispanic participants, but the EEG subsample was more likely to be younger (p < 0.001).
