Review Examining the course of hallucinatory experiences in children and adolescents: A systematic review Jose M. Rubio a, d, ⁎, Julio Sanjuán a, b , Ludwing Flórez-Salamanca c, d , Manuel J. Cuesta e a Spanish Mental Health Network (CIBERSAM), University of Valencia, Valencia, Spain b Clinic Hospital (INCLIVA), Valencia, Spain c Universidad Industrial de Santander, Bucaramanga, Colombia d Columbia University, New York State Psychiatric Institute, NY, USA e Psychiatric Unit B, Complejo Hospitalario de Navarra, Pamplona, Spain abstract article info Article history: Received 21 November 2011 Received in revised form 29 February 2012 Accepted 6 March 2012 Available online 30 March 2012 Keywords: Prospective Development Hallucinations Psychotic experience Psychotic continuum Background: Childhood and adolescence represent the periods during which hallucinatory experiences occur at the greatest prevalence, and also constitute a critical window of vulnerability for the pathogenesis of psy- chotic disorders. The longitudinal course of hallucinatory experiences during late childhood and adolescence, as well as their relationship to psychotic disorders, has never been the subject of review. Methods: We followed the PRISMA guidelines for conducting systematic reviews and combined the use of electronic and manual systematic search methods. Data were extracted upon pre-defined requested items and were analyzed using several epidemiological measures. The interpretation of the results was conducted in relation to the study design variables. Results: A total of 11 datasets (6 epidemiological and 5 clinical) were reviewed. The baseline prevalence of hallucinatory experiences ranged from 4.9% to 9%. Discontinuation occurred in between 58.7% and 94.5% of the cases, and person–year discontinuation rates ranged from 3% to 40.7% and appeared to be related to the duration of follow-up. Despite low person–year incidence rate, incident cases constituted between 27.7% and 83.3% of outcome samples. 2 of 3 studies showed evidence to predict transition to psychosis with likelihood ratios of 2.5 and 6.6. Conclusions: Hallucinatory experiences are a common experience during childhood and adolescence. A re- view of the current literature suggests that there is a considerable turnover of incident-discontinuing cases and that most cases discontinue in the short term. A subset of the cases was at risk for persistence or transi- tion to psychosis, probably related to indicators of severity of the hallucinatory experience. © 2012 Elsevier B.V. All rights reserved. 1. Introduction Research on psychotic experiences has recently challenged the categorical model of psychosis. The current literature acknowledges that in addition to representing one feature of psychotic disorders, psychotic experiences also occur as isolated phenomena in otherwise healthy individuals. Psychotic experiences are common, particularly during childhood and adolescence (Johns et al., 2002b; Yoshizumi et al., 2004), and the incidence in the general population can be as high as 25% (Johns and Van Os, 2001). Psychotic experiences present as an extended phenotype ranging from benign and transitory to that requiring medical care (Howes and Kapur, 2009). In particular, hallu- cinatory experiences play a relevant role in the relationship between psychotic experiences and psychotic disorders, as they may compli- cate with delusions and other psychotic symptoms and eventually need for care (Escher et al., 2002b; Smeets et al., 2010). Furthermore, hallucinations can be more reliably measured in the general popula- tion than other psychotic experiences (Kelleher et al., 2011). Examin- ing the course of hallucinatory experiences may be helpful for understanding their prognosis and their relationship with psychotic disorders. Notably, the greatest prevalence of hallucinatory experiences in the general population occurs during adolescence (McGee et al., 2000; Johns et al., 2002b; Yoshizumi et al., 2004) and coincides with a critical window of vulnerability for the pathogenesis of psychosis (Keshavan, 1999), suggesting commonalities in the etiologies of both phenomena (Van Os et al., 2009). Prospective studies on halluci- natory experiences in late childhood and adolescence have been implemented several times in different contexts (Garralda, 1984b; Kotsopoulos et al., 1987; Poulton et al., 2000; Dhossche et al., 2002; Escher et al., 2002a; Askenazy et al., 2007; Best and Mertin, 2007; Scott et al., 2009; Simon et al., 2009; Bartels-Velthuis et al., 2010; De Loore et al., 2011) although the longitudinal relationship between these hallucinatory experiences and the development of psychotic Schizophrenia Research 138 (2012) 248–254 ⁎ Corresponding author at: New York State Psychiatric Institute, 1051 Riverside Drive, Unit 69, New York, NY 10032, USA. Tel.: + 1 212 543 6201; fax: + 1 212 543 5515. E-mail address: rubiolo@nyspi.cpmc.columbia.edu (J.M. Rubio). 0920-9964/$ – see front matter © 2012 Elsevier B.V. All rights reserved. doi:10.1016/j.schres.2012.03.012 Contents lists available at SciVerse ScienceDirect Schizophrenia Research journal homepage: www.elsevier.com/locate/schres