Background: Evidence for basal hypothalamic-pituitary-adrenal (HPA) axis dysfunction in schizophrenia is less consistent than that seen in major depression. Potential reasons include sampling procedures and the use of patients on antipsychotic medications which may suppress the HPA axis. Therefore, the objective of this study was to determine whether first episode, drug naïve patients with schizophrenia have evidence of basal HPA axis dysfunction by measuring plasma levels of AVP, ACTH and cortisol from 13:00 to 16:00 h, a time frame which is believed to reflect 24 h concentrations of HPA axis activity.
Method: In this cross-sectional study, plasma levels of AVP, ACTH and cortisol were measured in 12 (7 males and 5 females) (mean age +/-SD=33.6+/-12.6 years) patients with DSM-IV schizophrenia and compared with those found in age- and sex-matched healthy controls.
Results: Patients and controls did not differ in terms of their 13:00 h cortisol and AVP. However, patients with schizophrenia had higher levels of ACTH as compared to control subjects at 13:00 h (41.3+/-14.6 vs. 12.4+/-1.1 pg/ml respectively; t=1.99, df=11, p <0.05). In comparison to controls subjects, patients with schizophrenia, had higher mean (+/-SE) AUC of ACTH (26.3+/-6.2 vs. 13.9 nmol/l, respectively; t=2.86, df=11, p <0.02) and cortisol (279.4+/-26.0 vs. 213.1+/-18.4 nmol/l, respectively; t=3.72, df=11, p <0.01). Though, patients with schizophrenia, in comparison to control subjects, had lower mean (+/-SE) AUC of AVP (0.87+/-0.24 vs. 1.42+/-0.34 pmol/l, respectively; t=2.29, df=11, p <0.02).
Conclusions: First episode, drug naïve patients with schizophrenia show evidence of basal overactivity of the pituitary-adrenal axis.