Sedation and memory: studies with a histamine H-1 receptor antagonist

The influence of sedation on the effect of an H-1 receptor antagonist on various cognitive functions, including memory, were evaluated.Diphenhydramine (50, 75 and 100mg) and lorazepam (0.5 and 1.5mg) were given on single occasions to 12 healthy volunteers (six males, six females) aged 20–33 (mean 23.4) years. Subjective assessments of sedation, sleep latencies, digit symbol substitution, choice reaction time, sustained attention and memory recall were studied 1.0h before and 0.5, 2.0 and 3.5h after drug ingestion. The study was double blind, placebo controlled and with a crossover design.With all doses of diphenhydramine there was subjective sedation, reduced sleep latencies and impairments in performance on the digit symbol substitution, choice reaction time and sustained attention tasks. No effects were observed with 0.5mg lorazepam. With 1.5mg lorazepam there was subjective sedation, fewer digit symbol substitutions, slowed choice reaction time, impaired attention and memory, but no effect on sleep lat...