Cannon M. Prevalence of psychotic symptoms in childhood and adolescence: a systematic review and meta-analysis of population-based studies. Psychological Medicine. 2012; 9:1-7. AuthorsIan Kelleher, Dearbhla Connor, Mary C. Clarke, Nina Devlin, Michelle Harley, and Mary Cannon This article is available at e-publications@RCSI: http://epubs.rcsi.ie/psychart/1 -Use LicenceAttribution-Non-Commercial-ShareAlike 1.0 You are free:• to copy, distribute, display, and perform the work.• to make derivative works. Under the following conditions:• Attribution -You must give the original author credit.• Non-Commercial -You may not use this work for commercial purposes.• Share Alike -If you alter, transform, or build upon this work, you may distribute the resulting work only under a licence identical to this one.

Hallucinations and delusions, the classic symptoms of psychosis, have recently been documented to occur at a much higher prevalence in the general population than clinically diagnosed psychotic disorder.1 A meta-analysis of prevalence studies of psychotic symptoms in young people demonstrated a median prevalence of 17% in children aged 9-12 years and 7.5% in adolescents aged 13-18 years.2 As the term suggests, psychotic symptoms have typically been considered to relate to psychotic disorder. Indeed, research has shown that members of the general population who report psychotic symptoms share a wide range of risk factors with people with schizophrenia (see Kelleher & Cannon for review), [3][4][5][6][7][8][9] and young people who report psychotic symptoms have been found to be at increased risk of psychotic disorder in adulthood.10,11 Individuals who report psychotic symptoms are also more likely to report non-psychotic psychopathological symptoms, especially symptoms of depression; [12][13][14][15][16] Yung et al, for example, reported that individuals who had a diagnosed depressive disorder endorsed an increased number of psychotic symptoms on the Community Assessment of Psychic Experiences questionnaire compared with controls.17 Bartels-Velthuis et al found that young adolescents who disclosed psychotic symptoms were approximately 3-5 times more likely to score in the clinical psychopathology range on the parent-completed Child Behavior Checklist. Community-based studies to date, however, have relied mainly upon questionnaires to assess psychotic symptoms and have involved limited data on non-psychotic psychopathology. In addition, although research suggests that psychotic symptoms are more common in younger than in older children, 2 there is a lack of information on whether there are differences in the clinical significance of psychotic symptoms across different stages of adolescence. In an attempt to improve our understanding of the clinical significance of psychotic symptoms in the general population we examined data from four population studies, comprising two large population surveys and two in-depth clinical interview studies of psychotic symptoms. The aims of this work were to investigate whether psychotic symptoms predicted nonpsychotic clinical diagnoses, and if so, which disorders; to investigate whether psychotic symptoms predicted more clinically severe disorder in terms of comorbid psychopathology (i.e. having more than one diagnosis); and to investigate whether the significance of psychotic symptoms varied as a function of age. MethodSurvey studies Background Epidemiological research has shown that hallucinations and delusions, the classic symptoms of psychosis, are far more prevalent in the population than actual psychotic disorder. These symptoms are especially prevalent in childhood and adolescence. Longitudinal research has demonstrated that psychotic symptoms in adolescence increase the risk of psychotic disorder in adulthood. There has been a lack of research, however, on the immediate clini...

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BackgroundRecent community-based research has suggested that psychotic experiences act as markers of severity of psychopathology. There has, however, been a lack of clinic-based research. We wished to investigate, in a clinical sample of adolescents referred to a state-funded mental health service, the prevalence of (attenuated or frank) psychotic experiences and the relationship with (i) affective, anxiety and behavioural disorders, (ii) multimorbid psychopathology, (iii) global functioning, and (iv) suicidal behaviour.MethodThe investigation was a clinical case–clinical control study using semi-structured research diagnostic psychiatric assessments in 108 patients newly referred to state adolescent mental health services.ResultsPsychotic experiences were prevalent in a wide range of (non-psychotic) disorders but were strong markers of risk in particular for multimorbid psychopathology (Z = 3.44, p = 0.001). Young people with psychopathology who reported psychotic experiences demonstrated significantly poorer socio-occupational functioning than young people with psychopathology who did not report psychotic experiences, which was not explained by multimorbidity. Psychotic experiences were strong markers of risk for suicidal behaviour. Stratified analyses showed that there was a greatly increased odds of suicide attempts in patients with a major depressive disorder [odds ratio (OR) 8.89, 95% confidence interval (CI) 1.59–49.83], anxiety disorder (OR 15.4, 95% CI 1.85–127.94) or behavioural disorder (OR 3.13, 95% CI 1.11–8.79) who also had psychotic experiences compared with patients who did not report psychotic experiences.ConclusionsPsychotic experiences (attenuated or frank) are an important but under-recognized marker of risk for severe psychopathology, including multimorbidity, poor functioning and suicidal behaviour in young people who present to mental health services.