THE AMNESIC ACTION OF BENZODIAZEPINES IN MAN

Benzodiazepines (BZs) may induce a massive but transient amnesia they affect the acquisition of new information, whereas retrieval of already learned information is unimpaired. As BZs can also be sedative, there is a question as to whether the amnesic effect is independent from the sedative effect. Although the comparison between these two effects depends on the methods used, there may well be at least a partial dissociation between amnesia and sedation: i) although BZs have the same sedative effect as barbiturates, only the BZs have an amnesic effect; ii) BZs as similar as oxazepam and lorazepam can lead to a similar sedation but a different amnesia; iii) the amnesic effect can be dissociated temporally from the sedative effect; iv) flumazenil antagonises but not synchronously the sedation and amnesia induced by diazepam; v) the tolerance for sedation is greater than that for amnesia. Thus BZs appear to have a specific amnesic effect, not uniquely secondary to their sedative powers, but increased by them. Practical and fundamental implications of this dissociation of effects are to be considered.