Dose effects of triazolam and alcohol on cognitive performance in healthy volunteers

Abstract

Benzodiazepines and alcohol are widely used psychoactive substances that have performance-impairing effects. Research suggests that the impairment profiles for benzodiazepines and alcohol differ, although few cognitive psychopharmacological studies have directly compared these drugs. This double-blind, double-dummy, placebo-controlled, repeated measures study directly compared the acute dose effects of triazolam (0.125, 0.25 mg/70 kg) and alcohol (0.40, 0.80 g/kg) in 20 social drinkers. At doses that produced comparable psychomotor impairment, triazolam was more likely to impair several objective measures of cognitive performance (e.g., episodic memory, divided attention) and to slow performance across several measures. However, only alcohol impaired accuracy on the digit symbol substitution and semantic memory tasks. In addition to objective measures, both drugs impaired awareness of performance impairments (i.e., metacognition) such that participants overestimated impairment, and the magnitude of this effect was generally larger for alcohol. Only triazolam impaired other measures of metacognition (e.g., error detection on a choice reaction time task). Future research might examine the clinical implications of the performance impairments reported here given the widespread use of benzodiazepines and alcohol.

Figure 1

Alcohol time-course functions for breath alcohol level. X-axis: time in minutes after capsule administration; arrow indicates start of beverage administration.

Figure 2

Triazolam (left panel) and alcohol (right panel) time-course functions for performance on the circular lights task. X-axis: time in minutes after capsule administration; arrow indicates start of beverage administration. Filled symbols indicate active drug values that are significantly different from placebo at that time point (p ≤0.05)

Figure 3

Mean peak percent predrug values for proportion correct and tracking moves on the divided attention task as a function of drug condition. Brackets show 1 S.E.M. An asterisk (*) indicates an active drug value that is significantly different from placebo and a dagger (†) indicates a significant difference between triazolam and alcohol at corresponding dose levels (p ≤ 0.05).

Figure 4

Mean data for working memory (Sternberg: median RT), episodic memory (recognition: d′), and semantic memory (general information: accuracy and quantity) measures as a function of drug condition. Brackets show 1 S.E.M. An asterisk (*) indicates an active drug value that is significantly different from placebo and a dagger (†) indicates a significant difference between triazolam and alcohol at corresponding dose levels (p ≤ 0.05).