Possible Interaction of Environmental and Biological Factors in the Etiology of Schizophrenia: Review and Integration

Abstract

Possible interactions of genetic and environmental factors in the etiology of schizophrenia are discussed. Studies on the significance of genetic-constitutional and environmental factors in determining specificity of behavioural and biochemical responses to stressors in humans and experimental animals are reviewed. Studies of stress in schizophrenia are also revieweed and their possible relationships discussed. Hypotheses related to the interaction of environmental factors and genetic constitutional factors in the production of acute schizophrenic psychosis in genetically predisposed people are presented. Research studies supporting such hypotheses are reviewed and discussed. It is proposed that environmental pressures, by inducing a physiological state of stress or other biochemical physiological alterations, may be etiologically related to the development of acute schizophrenic psychosis by: • Producing chemical substances that act as inducers of enzymes, in particular transmefhylating enzymes and those involved in the production of proteins, which may be related to the etiology of schizophrenia; • Activating autoimmune processes which may be related to the etiology of schizophrenia; • Changing levels of brain amines; •Altering the permeability of the blood-brain barrier.