What is already known on this topic?

Postictal psychosis is a well-recognised epileptic phenomenon, while there is also mounting evidence of increased prevalence of interictal psychosis and schizophrenia in people with epilepsy.1 The co-occurrence of these two disease states raises important questions about potentially shared pathological mechanisms and creates important challenges in their medical management.2

What does this paper add?

• First systematic review and meta-analysis examining the prevalence of psychosis in people with epilepsy.

• Pooled prevalence (a combination of lifetime, period and possibly point prevalence) of psychosis in those with epilepsy (including postictal psychosis, interictal psychosis and schizophrenia; 18 studies are included whose definition of psychosis is presumably unknown) alongside the odds of psychosis relative to those without epilepsy were reported.

Limitations

• The study authors comment on ‘substantial’ heterogeneity between included primary studies (I²>70%), and proceed with the meta-analysis using a random effects model to help accommodate this heterogeneity. Importantly, however, …