Prospects for a cognitive-developmental account of psychotic experiences.

PURPOSE It has recently been recognized that psychosis represents the end-point of abnormal developmental pathways. The neurodevelopmental framework, within which this observation has typically been interpreted, has a number of limitations, particularly its failure to take account of recent advances in our understanding of the psychology of unusual experiences, such as hallucinations and delusions. The purpose of the present review is to highlight the advantages of considering psychosis within the framework of mainstream developmental psychology. The approach we advocate integrates findings from neurodevelopmental research with research on typical cognitive and sociocognitive development and the psychology of psychotic symptoms. METHOD We review selected research on the developmental precursors of psychosis and on the role of cognitive processes in psychotic symptoms, together with relevant literature addressing the development of these processes in healthy children. RESULTS Developmental psychology provides clues about the cognitive and sociocognitive abnormalities that may be involved in hallucinations and delusions. An integration of these findings with existing knowledge on the neurodevelopment of psychosis suggests new avenues of research for investigators working at both biological and psychological levels of explanation. CONCLUSIONS The literature on typical cognitive and sociocognitive development provides a rich source of hypotheses about the ontogenetic pathways leading to psychosis.