LAUSR

BACKGROUND The P3 component of the event-related potential (ERP) has been particularly useful in alcohol research for identifying endophenotypes of alcohol-use disorder (AUD) risk in sober subjects. However, practice and/or fatigue reduce P3 amplitude, limiting the ability to ascertain acute and adaptive effects of alcohol exposure. Here, we report acute alcohol effects on P3 amplitude and latency using an adaptive stop signal task (aSST). METHODS One hundred forty-eight non-dependent moderate to heavy social drinkers, ages 21 to 27, participated in two single-blind, alcohol or placebo, counterbalanced sessions approximately 1 week apart. During each session, subjects performed an adaptive stop signal task (aSST) at 1) baseline, 2) upon reaching the target 60 mg/dL breath alcohol concentration or at the equivalent time during the placebo session, and 3) approximately 135 min later while the breath alcohol concentration was clamped. Here, we report on differences between baseline and first subsequent measurements across the experimental sessions. During each aSST run, the stop signal delay (SSD, the time between stop and go signals) adjusted trial-by-trial, based on the subject's performance. RESULTS The aSST reliably generated a STOP P3 component that did not change significantly with repeated task performance. The pre-infusion SSD distribution was bimodal, with mean values several hundred msec apart (FAST: 153 msec and SLOW: 390 msec). This suggested different response strategies: FAST SSD favoring "going" over "stopping", and SLOW SSD favoring "stopping" over "going". Exposure to alcohol at 60 mg/dL differentially affected the amplitude and latency of the STOP P3 according to SSD group. Alcohol significantly reduced P3 amplitude in the SLOW SSD compared to the FAST SSD group, but significantly increased P3 latency in the FAST SSD compared to the SLOW SSD group. CONCLUSIONS The aSST is a robust and sensitive task for detecting alcohol-induced changes in inhibition behavior as measured by the P3 component in a within-subject design. Alcohol was associated with P3 component changes, which varied by SSD group, suggesting a differential effect as a function of task strategy. Overall, the data support the potential utility of the aSST in the detection of alcohol response-related AUD risk.