Comorbid schizophrenia and psychotic symptoms in patients with bipolar disorder: a meta‐analysis of the global literature

Background

The boundary between bipolar disorder and schizophrenia has long been blurred by the shared psychopathology, genetic risk, and social factors. This study aims to examine the prevalence of psychosis and psychotic symptoms in bipolar patients.

Method

Key words ‘bipolar’, ‘psychosis’, ‘schizophrenia’, and the variants were searched in titles and abstracts using Medline, Psych INFO and Web of Science and forward and backward citation searches were conducted; effects were computed using single proportion analysis with double arcsine transformation.

Results

The final analysis comprised 285 studies. The comorbidity of schizophrenia diagnoses in bipolar patients was low (8%). However, more broadly defined mood incongruent psychosis was quite prevalent (47%). Similarly, psychotic symptoms were common in bipolar patients, specifically those with a type I diagnosis or manic episode; delusions were more common than hallucinations and thought disorders.

Conclusions

Significant overlap in phenomenology and psychopathology was observed between bipolar disorder and schizophrenia in this review. Future research should focus on comparing patients with similar symptoms and exploring the shared processes that contribute to these symptoms.