Dose-related effects of alcohol on cognitive functioning

Abstract

We assessed the suitability of six applied tests of cognitive functioning to provide a single marker for dose-related alcohol intoxication. Numerous studies have demonstrated that alcohol has a deleterious effect on specific areas of cognitive processing but few have compared the effects of alcohol across a wide range of different cognitive processes. Adult participants (N = 56, 32 males, 24 females aged 18-45 years) were randomized to control or alcohol treatments within a mixed design experiment involving multiple-dosages at approximately one hour intervals (attained mean blood alcohol concentrations (BACs) of 0.00, 0.048, 0.082 and 0.10%), employing a battery of six psychometric tests; the Useful Field of View test (UFOV; processing speed together with directed attention); the Self-Ordered Pointing Task (SOPT; working memory); Inspection Time (IT; speed of processing independent from motor responding); the Traveling Salesperson Problem (TSP; strategic optimization); the Sustained Attention to Response Task (SART; vigilance, response inhibition and psychomotor function); and the Trail-Making Test (TMT; cognitive flexibility and psychomotor function). Results demonstrated that impairment is not uniform across different domains of cognitive processing and that both the size of the alcohol effect and the magnitude of effect change across different dose levels are quantitatively different for different cognitive processes. Only IT met the criteria for a marker for wide-spread application: reliable dose-related decline in a basic process as a function of rising BAC level and easy to use non-invasive task properties.

Figure 1. Means and error bars (±1 SD) for blood alcohol concentration (BAC), together with individual BAC measures and target BAC levels at baseline and three alcohol time points (0.048, 0.082 and 0.100%).

The six data-points within each test block indicate the BAC reading at the commencement of each sub-test (i.e., Useful Field Of View, Self Ordered Pointing Task, Inspection Time, Traveling Salesperson Problem, Sustained Attention to Response Task and Trail Making Task).

Figure 2. Comparison of the mean baseline-normalized performance of the alcohol and control group participants across the eight dependent variables from the six cognitive abilities tests.

Error bars indicate one standard error of the mean. Significant differences between the control and alcohol groups are indicated by asterisks. UFOV = Useful Field of View; SOPT = Self-Ordered Pointing Task; IT = Inspection Time; TSP = Travelling Salesperson Problem; SART-OM = Sustained Attention Response Task – errors of omission; SART-CM = Sustained Attention Response Task – errors of commission; TMT-A = Trail Making Test A; TMT-B = Trail Making Test B.