Transcranial Magnetic Stimulation Combined With Electroencephalography Analysis Suggest Time-Dependent and Region-Specific Modulation of Cortical Excitability During Acute Alcohol Intoxication.

BACKGROUND: Longitudinal excessive alcohol consumption has adverse effects on brain structure and functions. The immediate effects of alcohol consumption on the activity and functioning of different circuits in the brain are less known. This exploratory study aimed to examine the effects of acute alcohol exposure on cortical activity in healthy adults. METHODS: The study included 34 adults, aged 29-36 years, who took part in the Youth and Alcohol Project's (YAP) alcohol exposure test. The participants' alcohol consumption was measured with the shortened version of the Alcohol Use Disorders Identification Test (AUDIT-C). Cortical functioning was investigated at baseline (BL) before alcohol intoxication, and 30 min (T2) and 120 min (T3) after alcohol intoxication using navigated transcranial magnetic stimulation combined with electroencephalography (TMS-EEG), focusing on TMS-evoked EEG potential (TEP) peaks P30, N45, P60, N100, and P180. The blood alcohol level was monitored using an alcohol breathalyzer. RESULTS: During alcohol intoxication, there were changes in the global mean field power (GMFP) and TEP magnitudes compared to BL. After alcohol consumption, the global mean field power (GMFP) amplitude decreased from approximately 80 ms poststimulus onward. For P30, N45, P60, and P180, the mean amplitude decreased in T2 compared to BL and recovered in T3. For N100, the mean amplitude decreased in T2 and in T3. Differences in TEP peaks between BL and T2 or BL and T3 were emphasized in frontal and central brain regions. CONCLUSIONS: The results suggest time-dependent and region-specific modulation of cortical excitability during acute alcohol intoxication. Alcohol's effects are dynamic, regionally heterogeneous, and not limited to simple global suppression. TMS-EEG offers a promising tool for assessing alcohol-related changes in cortical functions.