Abstract
Rationale Acute alcohol intoxication impairs cognitive and motor control, elevating risk in safety–critical contexts. While blood alcohol concentration (BAC) quantifies exposure, it does not reflect real-time functional impairment. Mobile, performance-based assessments may offer scalable detection tools, but their sensitivity under controlled alcohol challenge requires further validation. Objectives To evaluate the sensitivity of a mobile cognitive assessment (DRUID®) to alcohol-induced impairment across low and moderate intoxication levels and examined objective cognitive performance and subjective intoxication within a unified framework. Methods In a randomised, double-blind, placebo-controlled, within-subjects trial, 30 healthy adults (33% female; aged 23–49 years) completed neurocognitive testing following placebo, low-dose alcohol (mean peak BAC 0.04%), and moderate-dose alcohol (mean peak BAC 0.07%). Cognitive performance was measured using the Cambridge Neuropsychological Test Automated Battery (CANTAB) and DRUID®, while subjective effects were assessed via the Brief Biphasic Alcohol Effects Scale and a single-item intoxication rating. Results Moderate alcohol intoxication significantly impaired spatial working memory, sustained attention, and psychomotor control (all p < 0.05), and elevated DRUID® impairment scores at 130 min post-dose relative to placebo ( p < 0.001). Low-dose alcohol increased subjective intoxication and sedation (both p < 0.001) without measurable cognitive impairment. Conclusions Moderate alcohol produced persistent neurocognitive deficits despite dissociation between subjective and objective measures. Findings support performance-based impairment models and highlight mobile cognitive tools such as DRUID® as practical candidates for real-time functional assessment in applied safety settings. Trial registration ACTRN12623000528651, 19/05/2023.