EFFECTS OF LORAZEPAM AND DIAZEPAM ON CONSCIOUS AND AUTOMATIC MEMORY PROCESSES

Recent studies exploring benzodiazepine memory effects have used the d istinction between explicit and implicit tasks. There is now increasin g evidence that implicit tasks can be ''contaminated'' by conscious us es of memory and that unconscious (automatic) use of memory can contam inate explicit tasks, leading to mistaken estimates of their respectiv e influences on memory performance. The aim of the present double-blin d, double-placebo study was to assess the memory effects of diazepam a nd lorazepam using a process-dissociation procedure in a stem-completi on task, this procedure providing uncontaminated estimates of consciou s and automatic memory processes. The memory task was administrated to 60 healthy volunteers randomly assigned to one of three parallel grou ps (placebo, diazepam 0.3 mg/kg, lorazepam 0.038 mg/kg). Lorazepam mar kedly reduced conscious as well as automatic influences of memory. Dia zepam also reduced conscious uses of memory, albeit to a lesser extent than lorazepam, but did not decrease the influence of automatic memor y. Secondary analyses showed that when the deleterious effect on consc ious uses of memory was equated between a diazepam subgroup and the lo razepam group, only lorazepam impaired the automatic use of memory. Th is study strongly suggests a qualitative difference in the memory effe cts of the two benzodiazepines. It has some implications regarding the relationships between states of consciousness and memory processes.