There is large evidence that stress plays a crucial role in the pathophysiology and course of many psychiatric disorders. The stress-vulnerability model has been widely accepted for many years. Hypothalamic-pituitary-adrenal (HPA) axis dysregulation has been previously reported in schizophrenia. Patients in the acute phase of the disease seem to have an activated HPA axis (Holsboer-Trachsler et al. 1997) compared to patients who are clinically stable. Results from studies on ACTH regulation are inconsistent. abnormal dexamethasone suppression test (DST) results have been shown in normal aging, depression and schizophrenia. DST non-suppression was associated with cognitive impairment, ventricular enlargement and poorer prognosis (for review: Yeap and Thakore, 2005). Long-term hippocampal exposure to excessive levels of glucocorticoids can induce cognitive dysfunctions due to reduced neuronal volume of this limbic structure. the pharmacological reduction of glucocorticoid excess may help to improve cognitive functioning in schizophrenia.