a1 Research Unit for Schizophrenia Epidemiology, School of Psychiatry, University of New South Wales, Sydney, Australia
a2 Schizophrenia Research Institute, Sydney, Australia
a3 Department of Forensic and Neurodevelopmental Sciences, Institute of Psychiatry, King's College London, UK
a4 Clinical Research Unit for Anxiety and Depression, School of Psychiatry, University of New South Wales, Sydney, Australia
Background Psychotic-like experiences (PLEs) in the general population are common, particularly in childhood, and may constitute part of a spectrum of normative development. Nevertheless, these experiences confer increased risk for later psychotic disorder, and are associated with poorer health and quality of life.
Method This study used factor analytic methods to determine the latent structure underlying PLEs, problem behaviours and personal competencies in the general child population, and used item response theory (IRT) to assess the psychometric properties of nine PLE items to determine which items best represented a latent psychotic-like construct (PSY). A total of 7966 children aged 9–11 years, constituting 95% of eligible children, completed self-report questionnaires.
Results Almost two-thirds of the children endorsed at least one PLE item. Structural analyses identified a unidimensional construct representing psychotic-like severity in the population, the full range of which was well sampled by the nine items. This construct was discriminable from (though correlated with) latent dimensions representing internalizing and externalizing problems. Items assessing visual and auditory hallucination-like experiences provided the most information about PSY; delusion-like experiences identified children at more severe levels of the construct.
Conclusions Assessing PLEs during middle childhood is feasible and supplements information concerning internalizing and externalizing problems presented by children. The hallucination-like experiences constitute appropriate items to screen the population to identify children who may require further clinical assessment or monitoring. Longitudinal follow-up of the children is required to determine sensitivity and specificity of the PLE items for later psychotic illness.
(Received May 24 2011)
(Revised August 31 2011)
(Accepted September 06 2011)
(Online publication October 17 2011)
c1 Address for correspondence: Dr K. R. Laurens, Department of Forensic and Neurodevelopmental Sciences (Box P023), Institute of Psychiatry, King's College London, De Crespigny Park, London SE5 8AF, UK. (Email: Kristin.Laurens@kcl.ac.uk)