Conditions under which lorazepam can facilitate retrieval

Memory is composed of three stages: acquisition, consolidation, and retriev al. By impairing acquisition processes, benzodiazepines cause anterograde a mnesia while leaving intact information learned before the drug was taken. In some circumstances, retrieval of this information is even improved by be nzodiazepines. It has been hypothesized that this phenomenon is not a true facilitation of retrieval processes, but is the result of reduced interfere nce from items presented after drug administration and is thus a secondary consequence of drug-induced amnesia. Experiment 1 investigated the effect o f 0.5, 1, and 2.5 mg of lorazepam on explicit episodic memory in healthy yo ung volunteers. The l-mg dose was found to significantly improve recall of items presented before drug administration without causing amnesia for item s presented after drug administration, thus excluding an interference expla nation. Experiment 2 investigated the conditions necessary to obtain facili tated retrieval with 1 mg of lorazepam. The results showed that facilitatio n was found only when two lists of semantically related material were prese nted, but that both of the lists could be presented before drug administrat ion, thus excluding an effect of lorazepam on consolidation. Facilitation c ould be demonstrated in both direct (free recall) and indirect (backwards r eading) retrieval tasks and when all of the material was presented after lo razepam administration. This improved retrieval could therefore be of clini cal relevance, but any benefits would be reduced at higher doses that at th e same time impair acquisition of new information. However, because 1 mg of lorazepam is an effective anxiolytic dose, these results suggest that it i s possible to combine effective anxiety reduction with some benefits to mem ory.