Keele Research Repository

Epidemiological studies report high rates of schizophrenia in individuals with intellectual disability (ID). However, this subject has not been reviewed systematically. We aim to review studies that report the prevalence of nonaffective psychosis in a population with ID and estimate the prevalence of schizophrenia in this population. We performed a literature search using the PsychINFO, MEDLINE and EMBASE (from inception to 2 October 2014). We performed a manual search of citations from relevant papers identified through the databases. We identified 887 titles and after screening abstracts, identified 60 full-text articles. We identified 25 studies with 27 datasets for inclusion in the systematic review and meta-analysis. The prevalence rate was at least three times higher than the general population. There was a wide variation in the methodology, setting and sample size of the studies. Only one study reported a prevalence rate lower than the general population. The prevalence of psychosis in a population with ID is at least three times higher than that in the general population.