LORAZEPAM AND DIAZEPAM EFFECTS ON MEMORY ACQUISITION IN PRIMING TASKS

Unlike diazepam, lorazepam has repeatedly been shown to impair percept ual priming as well as explicit memory. To determine whether this dele terious effect was due to an impairment in acquisition of information, 60 healthy volunteers were randomly assigned to five treatment groups (placebo, lorazepam 0.026 or 0.038 mg/kg, diazepam 0.2 or 0.3 mg/kg) and successively performed perceptual priming tasks and a free-recall task. Priming performance on information learned before or 2 h after d rug administration, i.e. at the peak concentration of lorazepam, was a ssessed under the influence of the drugs, using a picture-fragment and a word-stem completion task. Free-recall performance was altered by b oth drugs. Lorazepam decreased priming performance when information wa s acquired after, but not before, drug administration, indicating that the drug alters the acquisition of information. Lorazepam also impair ed the ability to identify fragmented pictures, but there was no evide nce that this perceptual effect accounts for the priming impairment. S urprisingly, diazepam also decreased priming when information was acqu ired after drug administration, suggesting that, at least in certain c ircumstances, the two benzodiazepines may exert similar effects on pri ming measures.