Introduction

The anxiolytic actions of the benzodiazepines were discovered serendipitously and put to use clinically prior to an understanding of the underlying mechanism of action. Once it became apparent that their action resulted from an interaction with selective “benzodiazepine” receptors, it seemed natural to ask if endogenous benzodiazepines existed, analogous to the endogenous opioids (endorphins, enkephalins, etc.). Such substances were subsequently identified. End of the story? By no means. Although the presence of endogenous benzodiazepines in the human brain was no longer disputed, the source most certainly was. Were they synthesized in the brain, or did they end up there from the environment, including dietary intake? While this debate is discussed in this volume and is certainly fascinating, we take the approach that regarding the patient who is prescribed a benzodiazepine—it doesn’t really matter. In either case, it raises some significant questions about possible implications for patients’ response to benzodiazepine therapy, and for the manifestations and duration of withdrawal following the cessation of benzodiazepine therapy.