Platelet serotonin, plasma cortisol, and dexamethasone suppression test in schizophrenic patients

Background: Serotonin (5-HT) regulates hypothalamic-pituitary-adrenal (HPA) axis activity. Abnormal response to the dexamethasone suppression test (DST) and altered platelet 5-HT concentration have been shown in some schizophrenic patients. Methods: Platelet 5-HT and plasma cortisol concentrations were determined simultaneously in 86 male schizophrenic patients before and after DST. Basal plasma cortisol and platelet 5-HT levels were also determined in 69 healthy male persons. Results: Schizophrenic patients had higher plasma cortisol and platelet 5-HT concentrations than healthy persons. An abnormal escape from dexamethasone suppression was observed in 50% of patients. In these patients pre-dexamethasone cortisol and platelet 5-HT concentrations were higher than in patients with normal DST. Conclusions: This study demonstrates that schizophrenic patients have the HPA axis dysregulation that could be connected with a disturbance in the 5-HT system. (C) 1999 Society of Biological Psychiatry.