[Childhood adverse traumatic experiences and schizophrenia]

Abstract

Εpidemiological research during last decades has demonstrated the association of certain environmental variables with psychosis. Ιn parallel with understanding environmental contributors to schizophrenia, identification of those at high risk of psychosis has become a priority. These risk factors include adverse traumatic experiences, such as discrimination, social environment adversities, bullying, emigration and childhood trauma. For many years the possibility of a relationship of adverse traumatic experiences with schizophrenia was minimized in favor of a biological paradigm. However, there is evidence supporting that childhood adversities is one of the most significant environmental risk factors for psychosis, if not the most significant. Studies have demonstrated the validity and the reliability of retrospective reports of adverse traumatic experiences in psychotic patients. The question on the causal relationship between adverse traumatic experiences and psychosis has been raised for many years, but it has not yet been answered. Researchers have focused on the study of dysfunctional cognitive schemes being formed due to childhood adversities and interpreting the world as unfriendly and threatening. According to social defeat hypothesis, the patients do not experience more stressful life events but they experience them as less controllable. Furthermore, researchers study the mediator psychopathology associated directly with adverse traumatic experiences, such as anxiety, mood, dissociative and adaptation disorders, which possibly predispose to psychosis. Cannabis use and childhood adversities may interact to increase the risk of psychotic symptoms in adolescence, according to research findings. Several publications have positively linked the number of traumatic adverse experiences with the severity of mental health and possibly with high risk of psychosis in a dose-response relationship model. Taking note that it is important to have a plausible hypothesis of the biological mechanisms involved with the relationship between adverse traumatic experiences and psychosis, the putative systems being explored are: (1) the hypothalamus-pituitary-adrenal (HPA) axis because it mediates the principal adaptive response to perceived psychological or physiological stress and (2) the dopamine system, which is considered to be important in the development of psychosis. The biological and environmental risk factors are both important in the etiology of psychosis but the effects of some forms of childhood adversity act largely independently of pre-existing genetic liability to increase the risk of psychosis. A supposed differentiation of psychosis associated with adverse traumatic experiences from the classic neurodegenerative model possibly should be considered seriously by the clinician in order to design the best therapeutic plan.