Environmental risk factors and schizophrenia

Schizophrenia has long been described as a disease of "unknown etiology," one "suspected" of having developmental origination. In our review, we explore the emergence of schizophrenia and its origins. Our findings are presented sequentially across development, beginning with an examination of risk factors related to exposures or conditions of parents prior to conception. A major example of this category is advanced paternal age, a well-replicated risk factor for schizophrenia. We next consider prenatal development, and focus on the period between conception and birth. A discussion of in utero exposures to infectious agents, nutritional deprivation, and chemical exposures is included. The final developmental stage surveyed is the postnatal period, and those events or exposures, including obstetric complications at birth and exposure to trauma, which can be further divided into perinatal and later exposures. Throughout the review, we discuss the relevance of these factors to neurodevelopment, the strength of the supporting evidence, and the potential directions for new research.