Endogenous opiates and schizophrenia: directions in clinical research.

In the past decade both basic and clinical research on endogenous opiates has involved many aspects of medicine. This review focuses on the clinical literature that relates physiology and pathophysiology of the endogenous opiates to schizophrenia. Three major investigative approaches are described and their results evaluated. These approaches are described and their results evaluated. These approaches include assays of endogenous opiates in the context of clinical illness and use of exogenous opiates as well as exogenous opiate antagonists in the treatment of clinical illness. Current understanding at both the basic science and clinical research levels does not allow firm conclusions about the role of endogenous opiates in schizophrenia; however, the evolution of the growing understanding is used by the author to provide a speculative hypothesis.