A comparison between transient amnesias induced by two drugs (diazepam or lorazepam) and amnesia of organic origin.

The transient amnesias produced by drugs may have much in common with the more permanent amnesias associated with organic brain damage. This possibility was investigated using two benzodiazepines, diazepam and lorazepam, with medical student volunteers. In Experiment 1, 27 subjects received a 2ml intravenous injection of either diazepam (7.5 mg) or of lorazepam (3.0 mg) or of normal saline. In Experiment 2, a further 13 subjects were given lorazepam (2.5 mg) or saline. A double blind procedure was used. Neither drug had an appreciable effect on span-type short-term memory (except with 2-channel presentation). Both drugs produced severe anterograde amnesia in other forms of memory test: the amnesic effect of lorazepam lasted for several hours. This amnesia was not attributable to failures of perception. Lorazepam appeared to affect recognition even more than recall. In a test with lorazepam no evidence was obtained that the drug increases susceptibility to proactive interference. With both drugs, recall and recognition were unimpaired of material presented about 10 min before the injection; this shows that the drugs did not affect retrieval mechanisms.