From predisposition to psychosis: progression of symptoms in schizophrenia.

Schizophrenia is increasingly viewed as a neurodevelopmental process caused by an interaction between genetic factors and environmental stressors. Prospective studies and retrospective research using objective data indicate that behavioural deviations can be dated to early infancy and cut across multiple behavioural domains. In adolescence, preschizophrenics exhibit subtle changes in cognition and affect as well as a variety of anomalous subjective experiences (so-called 'basic symptoms'), suggesting 'trait' status of these features. Prodromal symptoms occur in a substantial proportion of preschizophrenics, followed by a short prepsychotic phase with the crystallization of a psychotic syndrome. Clinical, phenomenological and conceptual aspects of these early preschizophrenic phases are reviewed, and their neurobiological implications are briefly addressed. It is concluded that there is an urgent need for detailed and multidisciplinary prospective studies, but that the evidence accumulated to date is sufficient to justify research-based secondary prevention programmes.