Subtle motor, emotional, cognitive and behavioural abnormalities are often present in apparently healthy individuals who later develop schizophrenia, suggesting that some aspects of causation are established before overt psychosis.

To outline the development of schizophrenia.

We drew on evidence from The Northern Finland 1966 Birth Cohort supplemented by selected findings from other relevant literature.

The main known risk factors in development of schizophrenia are genetic causes, pregnancy and delivery complications, slow neuromotor development, and deviant cognitive and academic performance. However, their effect size and predictive power are small.

No powerful risk factor, premorbid sign or risk indicator has been identified that is useful for the prediction of schizophrenia in the general population.

Neurobiological studies of the early course of psychoses, such as schizophrenia, allow investigation of pathophysiology without the confounds of illness chronicity and treatment.

To review the recent literature on the biology of the early course of psychoses.

We carried out a critical appraisal of the recent findings in the neurobiology of early psychoses, using structural, functional and neurochemical imaging techniques.

Brain structural alterations are present early in the illness and may predate symptom onset. Some changes, notably those in frontal and temporal lobes, can progress during the early phases of the illness. Functional and neurochemical brain abnormalities can also be seen in the premorbid and the early phases of the illness. Some, although not all, changes can be trait-like whereas some others might progress during the early years.

A better understanding of such changes, especially during the critical periods of the prodrome, around the transition to the psychotic phase and during the early phases of the illness is crucial for continued research into preventive intervention strategies.