Dissociations in the expression of the sedative effects of triazolam

Fifteen normal volunteers were administered 0.250, 0.375, and 0.500 mg of triazolam and placebo in a double-blind repeated measures cross-over design. Subjects demonstrated dose-dependent impairments in free recall, a test of explicit memory requiring awareness and reflection, and sedation as assessed by objective behavioral measures (the digit symbol substitution task) and subjective visual analogue scales. The sedative drug response did not account for the impairment in free recall. Differences in performance of the two tests of sedation indicated that the effect of this drug on reflective processes accounts for impairment in episodic memory and the inability to track the sedative effects of this drug at the higher doses tested in this study.