Understanding putative risk factors for schizophrenia: retrospective and prospective studies.

This paper describes a research program intended to provide a better understanding of the influence of several putative risk factors for schizophrenia on child development and psychosis. Two related components of the overall program are described: the retrospective EnviroGen projects, which use a variety of putative risk factors to explain variance in several dimensions of schizophrenia and in psychotic symptoms in community controls, and Project Ice Storm, which prospectively examines the effects of prenatal maternal stress in the children of women who were exposed to the 1998 Quebec ice storm during their pregnancies. The EnviroGen projects have been successful in explaining variance in several dimensions of illness, including premorbid adjustment and severity of dissociative symptoms. Project Ice Storm has demonstrated the noxious effects of prenatal stress on cognitive and language development in children. We have also found that "ice storm children" exposed in specific weeks of gestation show greater dermatoglyphic asymmetry, as has been reported for samples of patients with schizophrenia. In both studies, prenatal maternal stress has been associated with more severe childhood behaviour problems. The combination of retrospective and prospective studies is a rich source of triangulated results providing information about developmental psychopathology.