Statistical analysis
Descriptive analysis was used to assess participant demographics and substance use history. Linear fixed-effects models with restricted maximum likelihood were employed to examine the impact the of condition (placebo, alcohol, alprazolam and combined alcohol and alprazolam), time (30 and 100 min) and their interaction on cognitive performance and subjective mood. Compound symmetry was selected as the optimal variance structure based on Akaike’s information criterion. Initially, condition by time interactions were examined. In the absence of a significant interaction, an exploratory analysis of the main effects was conducted, and Bonferroni-corrected pairwise comparisons were utilised to compare treatment effects with the placebo condition. Outliers were screened in the cognitive data prior to analysis. An exploratory approach was taken for outlier handling, considering factors such as reaction time patterns and performance consistency. Values influenced by factors external to the intended experimental conditions, such as distraction or equipment malfunction, were removed from the dataset. A sensitivity analysis was performed to assess the impact of outliers on the findings, which showed minimal or slightly more significant differences when including outliers. Statistical analyses were conducted using IBM SPSS Statistics (Version 29), and all tests were two-tailed with a significance level of 