(Des-Tyr)gamma-endorphin for schizophrenia. A critical review.

(Des-Tyr)-gamma-endorphin is a naturally-occurring neuropeptide. It has no opiate-like activity, and animal research suggests that it shares with haloperidol certain effects on animal behaviour. The compound was given to schizophrenics, and initial claims of 'a reduction or total disappearance of symptoms in schizophrenics partly or completely resistant to conventional neuroleptics and suffering from long-lasting psychoses' were made. Several investigators have attempted to replicate these findings without success. This paper reviews the shortcomings in methodology and interpretation of results of the investigations carried out so far and emphasises that the fundamental question of whether (Des-Tyr)-gamma-endorphin has any clinical antipsychotic effect has not been answered by any study to date.