Examining the course of hallucinatory experiences in children and adolescents: a systematic review

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 psychotic 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.

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.

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.

Hallucinatory experiences are a common experience during childhood and adolescence. A review 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 transition to psychosis, probably related to indicators of severity of the hallucinatory experience.