Aims: To investigate the acute effects of intravenous alcohol and its metabolite acetaldehyde on cognitive function in healthy individuals. Design: Experimental pre-test/post-test design. Setting: Kurihama Medical and Addiction Center, Japan. Participants: A total of 298 healthy Japanese people age 20 to 24 years. Measurements: Participants underwent an intravenous alcohol infusion with a target blood alcohol concentration (BAC) of 0.50 mg/mL for 180 minutes. Participants completed the continuous performance test (CPT) for sustained attention, the paced auditory serial addition test (PASAT) for working memory, and the reaction time test (RTT) for speed/accuracy, along with the blood test for BAC and blood acetaldehyde concentration (BAAC) at baseline, 60 and 180 minutes. Findings: Although the target BAC was maintained during the infusion, BAAC peaked at 30 minutes and then gradually declined (η2 = 0.18, P < 0.01). The CPT scores worsened, and the changes between 0 and 60 minutes were correlated with BAAC (correct detection, η2 = 0.09, P < 0.01; r = −0.34, P < 0.01; omission errors, η2 = 0.08, P < 0.01; r = 0.34, P < 0.01). PASAT scores improved through 180 minutes, whereas the changes between 0 and 60 minutes were negatively correlated with BAAC (task one, η2 = 0.02, P < 0.01; r = −0.25, P < 0.01; task two, η2 = 0.03, P < 0.01; r = −0.28, P < 0.01). Although RTTs worsened, they were not associated with BAC or BAAC. None of these comparisons maintained the time effect after controlling for body height. Conclusions: Acetaldehyde exposure following acute intravenous alcohol appears to have a negative impact on sustained attention and working memory, whereas there seems to be only a minor effect of moderate alcohol concentration on speed and accuracy.
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