Benzodiazepine-induced amnesia and anaesthetic practice: a review

Anaesthetic practice is the only clinical context in which amnesia is a valued property of benzodiazepine drugs, since decreased recall considerably enhances patient tolerance and acceptance or surgical and diagnostic procedures. Research on the amnesic effects of diazepam, midazolam, lorazepam and flunitrazepam, administered via oral, i.v. or i.m. routes to patients undergoing surgical or diagnostic procedures is reviewed. The degree of anterograde amnesia is a function of the drug, the route of administration and the population of patients being assessed. Retrograde amnesia has not been conclusively demonstrated. Amnesia is more profound for cutaneous-tactile and auditory than for visual stimuli, but actual surgical events, or emotionally laden material, are more likely to be recalled than artificial stimuli. Evidence that the benzodiazepines prevent affective and cognitive processing under general anaesthesia and decrease traumatic postoperative recall of intra-operative events is reviewed. The explanatory value of modern theories of memory for research on benzodiazepine-induced amnesia, and the research potential of the surgical setting are outlined. The development of non-sedative anxiolytics and specific benzodiazepine antagonists provides the tools for assessing the contribution of sedative and anxiolytic properties of drugs to their amnesic effects.