The stress cascade and schizophrenia: etiology and onset.

Psychosocial stress is included in most etiologic models of schizophrenia, frequently as a precipitating factor for psychosis in vulnerable individuals. Nonetheless, the stress-diathesis model has not been tested prospectively in prodromal patients as a predictor of psychosis. The biological effects of stress are mediated by the hypothalamic-pituitary-adrenal (HPA) axis, which governs the release of steroids, including cortisol. The past few decades have witnessed an increased understanding of the neural effects of stress and cortisol, including both normal and abnormal diatheses. As few biological markers have been evaluated as risk factors for psychosis in prodromal patients, the HPA axis and its interaction with intervening life events are apt candidates for study. In this article, we review the HPA axis and its neural effects, present a model for how stress might precipitate psychosis in vulnerable individuals, review the empirical evidence of a link between stress and schizophrenia symptoms, and propose a research design and appropriate statistical models to test the stress-diathesis model for psychosis onset in prodromal patients.