Diurnal rhythm of plasma beta endorphin, cortisol and growth hormone in schizophrenics as compared to control subjects.

The diurnal variation of plasma beta endorphin was studied in ten schizophrenics, and in age/sex matched control subjects. In the controls beta endorphin was high in the morning (21.0 +/- 3.5 pmol/l) and decreased towards evening. In the schizophrenic group the beta endorphin fluctuated randomly, ranging within 9-40 pmol/l throughout the day. Plasma cortisol showed a normal diurnal pattern in both groups. The mean plasma cortisol levels in the schizophrenics were significantly higher than in the controls throughout the day. The pattern of plasma human growth hormone (hGH) level was similar in both groups at the time tested. It is hypothesized that the instability of beta endorphin secretion may contribute to the pathogenesis of schizophrenia.