Effects of oxazepam and an extract of kava roots (Piper methysticum) on event-related potentials in a word recognition task.

Twelve healthy volunteers were tested in a double-blind crossover study to assess the effects of oxazepam and an extract of kava roots (Piper methysticum) on behavior and event-related potentials (ERPs) in a recognition memory task. The subjects' task was to identify within a list of visually presented words those that were shown for the first time and those that were being repeated. The repeated words were associated with an increased positivity beginning approximately 250 ms poststimulus. Oxazepam led to a reduction of a negative component in the 250-500 ms range for both old and new words and to a reduction of the old/new difference in the ERP associated with a significantly worse recognition rate. Kava on the other hand showed a slightly increased recognition rate and a larger ERP difference between old and new words.