Study design
The study was a single-blind, placebo-controlled, randomized design with participants completing three study visits within 3 weeks (Fig. Upon arrival for all study visits, participants were breathalyzed (Intoxilyzer 800, CMI, Inc, Owensboro, KY) to ensure a 0.00 BAC. For all breathalyzer measurements, breath alcohol content (BrAC) was measured and reported as equivalent BAC. Weight was measured at each visit to calculate the appropriate alcohol dose. Participants were asked to verbally confirm that they had fasted for 3 h, had refrained from alcohol for 24 h, were not taking any medications that were contraindicated with alcohol, and had arranged a ride home before the session started. Participants of child-bearing potential were required to take a urine pregnancy test if there was not a negative pregnancy test on record within 7 days of all study visits. At the initial visit, age was verified with a photo ID and participants completed a demographics questionnaire including handedness along with the Questionnaire Measure of Habitual Alcohol UseParticipants were trained on the Go/No-go task and practiced the task on their first study visit with 2 example blocks, one with go-only trials and one with both go and no-go trials. At each visit, participants completed a baseline run of the Go/No-go task with the Flow1 headset before receiving a study beverage. They also completed a resting state task (data not reported).Alcohol dosing was based on Widmark’s equationAfter finishing the drinks, participants were breathalyzed every 5 min starting at 10 min. During this time participants were allowed to read or watch a show. One of the following had to occur before starting the second set of the Go/No-go task: (1) a participant reached a BAC of 0.03 for low dose or 0.07 for moderate dose sessions, (2) BAC peaked somewhere under 0.03 or 0.07 and went down in 2 successive measurements or (3) 30 min passed if 1 or 2 did not occur. For the placebo dose, participants were breathalyzed twice, at 10 and 15 min after finishing the drink, before returning to the task. The mean ± standard deviation time-to-starting the second brain recording segment was 21.67 ± 7.67) minutes for the moderate dose and 18.65 ± 8.08 min for the low dose.Before beginning the second set of tasks, participants completed the BAES with an additional question asking to report any tobacco usage in the 2 h before the study visit (none was reported for any participant at any visit). The Flow1 headset was then placed and participants completed the Go/No-go task and a resting state task (resting state data not reported). After the second Go/No-go task, participants completed the BAES once again with an additional question asking how many shots of alcohol they thought they received that day. Participants were required to wait onsite for 30 min before they were allowed to leave with their pre-arranged transportation, which did not include driving or riding a non-motorized transportation. Participants were offered food and beverages during the wait period and were breathalyzed at the end of the visit.