Developmental precursors and biological markers for schizophrenia and affective disorders: specificity and public health implications.

Schizophrenia's developmental dimension includes causes being active early in life. Precursors are manifest before psychosis begins, and there is an emerging public health agenda including prediction and prevention. We discuss the specificity of some developmental precursors to schizophrenia as an outcome, with particular reference to longitudinal birth cohort studies. Underlying structural brain abnormalities are considered. Differences from controls are found in schizophrenia and, to a lesser extent, before affective disorder on many measures. This apparent lack of specificity may not be the case in neurobiological terms, as underlying mechanisms may be different; parsimony suggests not. This same lack of specificity may be an advantage in public health terms, raising the possibility of strategies to predict and prevent a range of psychiatric disorders, not just schizophrenia.