Naloxone's effect on cognitive functioning in drug-free and diazepam-treated normal humans.

Ten normal male volunteers were administered oral diazepam (0.25 mg/kg) or placebo followed 45 min later by IV naloxone (1.2 mg) or placebo. Diazepam produced a marked decrement in performance on tests of memory, visual psychomotor skills, reaction time, and time production. Naloxone alone had no effect on these measures and failed to interact with the diazepam. These findings do not support a role of the endogenous opioid system in normal human cognitive processes or in the behavioral effects of diazepam.