During Ascending and Descending Limbs of the Blood Alcohol Concentration Curve

Blood alcohol concentrations (BACs) as low as 0.04 mg/ml impair cognitive and visual tasks such as planning, working memory, blurred vision, and spatial awareness. Neuropsychological tests, such as the trail making test (TMT), have been shown to assess the severity of impairment. Prior research in this area has exclusively assessed these impairments via driving performance. This study aimed to investigate neurocognitive impairments associated with varying BAC levels utilizing a computerized trail making test (cTMT), which reduces practice effects via randomized stimuli location. The influences of alcohol were tested over the variables of total time, median latency, and version (Trail A, Trail B). Twenty-six participants (8 male, 18 female) with a minimum age of 21 years were recruited. Participants were randomly selected to be in the placebo (n=7) or the experimental group (n=19). The experimental group performed the cTMT at four target BAC points: baseline (0.00 mg/ml), ascending (0.06 mg/ml), peak (0.08 mg/ml), and descending (0.06 mg/ml). While participants who received alcohol tended to report themselves at a lower BAC than they were, there was no significant difference between perceived and actual BAC. Additionally, alcohol did not significantly affect performance on the cTMT for the tested levels. The cTMT detected impairments during the complex task (Trail B) but not in the simpler task (Trail A), thus indicating cognitive inflexibility and deficits in working memory. Future studies could attempt to augment BAC levels to at least 0.10 mg/ml in order to examine more distinct effects of alcohol on the specific cognitive tasks required by the cTMT. Abbreviations: BAC – Blood Alcohol Concentration; CNS – Central Nervous System; cTMT – computerized Trail Making Test; GABA – Gamma-Aminobutyric Acid; NMDA - N-Methyl-D- Aspartate; PI – Principle Investigator; TMT – Trail Making Test