The prevalence and correlates of hallucinations in Australian adolescents: Results from a national survey

Abstract

There is an emerging interest in children and adolescents who have hallucinations and other psychotic-like experiences to enable identification of those potentially at risk for schizophrenia in adulthood. This study examines the prevalence, demographic and clinical correlates of hallucinations in the adolescent subgroup of the Australian National Survey of Mental Health and Well-Being. Participants were a nationally representative sample of 1261 adolescents aged 13–17 years. Adolescents completed self-report questionnaires with two questions relating to hallucinations and questions pertaining to depressive symptoms and cannabis use. Parents completed the Child Behavior Checklist (CBCL) and the Diagnostic Interview Schedule for Children (DISC-IV).

Hallucinations were reported by 8.4% of adolescents. Those living in blended or sole parent families were more likely to report hallucinations than those living with both biological parents (OR 3.27; 95% CI 1.93, 5.54; OR 2.60; 95% CI 1.63, 4.13 respectively). Hallucinations were more prevalent in adolescents who scored in the highest decile of the CBCL or had elevated depression symptoms (OR 3.30; 95% CI 2.10, 5.20; OR 5.02; 95% CI 3.38, 7.45 respectively). Hallucinations were associated with depressive disorder (OR 2.70; 95% CI 1.16, 6.28) and were more prevalent in those adolescents who had smoked cannabis more than twice in the month prior to the survey (OR 3.27; 95% CI 1.76, 6.08). Hallucinations occur relatively frequently in adolescents and are associated with a range of demographic and clinical correlates. Further research may assist in understanding the variable trajectory of children and adolescents who hallucinate.

Introduction

Investigators have examined the role that psychotic symptoms in childhood may have for predicting later psychosis (Laurens et al., 2007, Poulton et al., 2000, Welham et al., in press). As a result, hallucinations in children and adolescents are emerging as an important area of research. To date, there are five community surveys examining these phenomena.

A Japanese study using a self-report questionnaire found 21% of 761 children aged 11 or 12 years experienced hallucinations. Subjects who had combined auditory and visual hallucinations scored significantly higher on measures of anxiety and dissociation. The authors suggested that hallucinations experienced in two modalities were more likely to be associated with distress (Yoshizumi et al., 2004).

Clinical Interviews using the Diagnostic Interview Schedule for Children (DISC) (Costello et al., 1982) in the Dunedin birth cohort study revealed that 8% of 788 subjects at age 11 had hallucinatory experiences. Subjects with hallucinations were more likely to have higher symptom scores for anxiety, depression and inattention-hyperactivity (McGee et al., 2000).

Using two items from the Youth Self Report (YSR) (Achenbach, 1991a), auditory and visual hallucinations were found in 5% and 2% of a population based sample of 914 adolescents from the Netherlands (Dhossche et al., 2002). There were no significant associations between hallucinations and age or gender. Auditory and visual hallucinations were associated with a total problem score in the clinical range on the YSR (OR 11.3; 95% CI 5.9, 21.8; OR 13.0; 95% CI 5.1, 33.2 respectively).

To examine antecedents for schizophrenia, Laurens and colleagues (2007) studied 548 London children aged 9–12 for psychotic-like experiences and other putative risk factors (Laurens et al., 2007). Auditory and visual hallucinations were self reported by 29.9% and 28.3% of the children respectively. Care givers reported only 1.9% of the children experiencing hallucinations in either modality. A subsequent study of this population reported that children of African Caribbean ethnicity were more likely than white British children to report psychotic-like experiences (OR 1.62, 95% CI 1.02, 2.81) (Laurens et al., 2007).

The ALSPAC birth cohort of more than 6000 children aged 12 years found 38.9% of children self reported psychotic-like experiences. These children were then interviewed by clinicians. The prevalence using observer rated instruments reduced to 13.7%. Auditory hallucinations were observed in 7.3% of the sample. Positive Predictive Values for the screen questions compared to observer rated scores were low except for auditory hallucinations (Horwood et al., 2008).

In this current study, we report the prevalence, demographic and clinical correlates of hallucinations in a nationally representative sample of 13 to 17 year olds in Australia.