The antecedents of schizophrenia: a review of birth cohort studies.
BACKGROUND
Birth cohort (BC) studies demonstrate that individuals who develop schizophrenia differ from the general population on a range of developmental indices. The aims of this article were to summarize key findings from BC studies in order to identify areas of convergence and to outline areas requiring further research.


METHODS
We define BC studies as studies based on general population BCs where data are collected prospectively from birth or childhood and which identify schizophrenia or related disorders as an outcome. To identify such studies, we searched various electronic databases using the search parameters (schizo* OR psych*) AND (birth cohort). We also checked the references of relevant articles and previous reviews.


RESULTS
We identified 11 BCs from 7 countries that have examined schizophrenia as an outcome in adulthood. There is relatively consistent evidence that, as a group, children who later develop schizophrenia have behavioral disturbances and psychopathology, intellectual and language deficits, and early motor delays. Evidence with respect to alterations in language, educational performance, and physical growth has also been identified in some studies. BC studies have also contributed evidence about a wide range of putative risk factors for schizophrenia.


CONCLUSIONS
BC studies have provided important, convergent insights into how the developmental trajectory of individuals who develop schizophrenia differs from their peers. The combination of new paradigms and larger cohorts, with the tools of modern epidemiology and biomedical science, is advancing our understanding of the developmental pathways to schizophrenia.
Welham
Joy
J
Queensland Centre for Mental Health Research, The Park Centre for Mental Health, Wacol, QLD 4076, Australia. john_mcgrath@qcmhr.uq.edu.au
Isohanni
Matti
M
Jones
Peter
P
McGrath
John
J
D000293:Adolescent; D000328:Adult; D015984:Causality; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D003431:Cross-Cultural Comparison; D002658:Developmental Disabilities / Q000175:diagnosis / Q000453:epidemiology* / Q000209:etiology*; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008137:Longitudinal Studies; D008297:Male; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects / Q000175:diagnosis / Q000453:epidemiology / Q000209:etiology; D012189:Retrospective Studies; D012307:Risk Factors; D012559:Schizophrenia / Q000175:diagnosis / Q000453:epidemiology* / Q000209:etiology*; D055815:Young Adult