Effects of low doses of lorazepam on psychometric tests in healthy volunteers.

The effects of low oral doses of lorazepam on several cognitive and performance tasks were investigated in 50 healthy students. A double-blind, parallel group design was used to compare five treatments: placebo and lorazepam 0.5, 0.75, 1 mg and progressive doses up to 1.5 mg. After randomization, all subjects received placebo for 3 days in a single-blind procedure followed by five consecutive days of treatment. Subjects completed a battery of tests each day of the 5 days active treatment and the day after stopping the treatment. There were no significant differences between placebo and lorazepam on the free recall test and the critical flicker fusion frequency test, but lorazepam produced significant improvement on the digit symbol substitution test and the choice reaction time test. We suggest that low repeated doses of lorazepam in healthy subjects improve the psychomotor performance without sedation and memory impairment.