Discrepancy between self-reported intoxication and psychomotor vigilance task performance after alcohol intake: associations with BrAC, alcohol-metabolizing genotypes, and drinking tendency

The degrees of subjective intoxication (SI) and vigilance impairment following alcohol consumption vary among individuals. This variability may reflect both metabolic enzyme genotypes and drinking behavior. The purpose of this study was to examine the integrated associations among alcohol-metabolizing enzyme genotypes, drinking tendency, and acute alcohol-induced changes in breath alcohol concentration (BrAC), SI, and vigilance performance.

Alcohol (0.5 g/kg body weight) was orally administered to 93 healthy adults. BrAC, SI, and the Psychomotor Vigilance Task (PVT) were measured at multiple time points between 0 and 100 min. Repeated-measures ANOVA was performed with time as the within-subject factor and alcohol dehydrogenase 1B (ADH1B) and aldehyde dehydrogenase 2 (ALDH2) genotypes as between-subject factors. Additionally, using structural equation modeling (SEM), we examined how BrAC, SI, and PVT lapse rates were jointly related to genotypes and the Alcohol Use Disorders Identification Test–Consumption (AUDIT-C) score.

For BrAC and SI, a significant ALDH2 × time interaction was observed. ALDH2*1/*1 participants had lower BrAC than ALDH2*1/*2 participants. Regarding PVT performance, the main effect of time was observed, but no significant main effects or interactions involving genotypes were found. Additionally, results from SEM showed that, in the 40-min model, BrAC positively predicted SI and lapse rate, and AUDIT-C negatively predicted SI but not lapse rate. ALDH2 genotype positively predicted AUDIT-C and negatively predicted BrAC; ALDH2 genotype also showed a significant direct negative path to SI but not on lapse rate. In the 100-min model, BrAC positively predicted SI but not lapse rate, and AUDIT-C negatively predicted SI but not lapse rate.

ALDH2 genotype contributed to variability in BrAC and SI but not PVT performance. In the 40-min SEM model, higher AUDIT-C predicted lower SI despite no association with BrAC or PVT lapse rate. This pattern suggests a discrepancy between self-reported intoxication and PVT performance. These findings may inform risk communication and intervention strategies to reduce alcohol-related accidents and improve health education.

UMIN Clinical Trials Registry (UMIN-CTR), UMIN000055964, registered on 2024–10-28.