BACKGROUND This study tests the hypothesis that epilepsy increases the risk of developing schizophrenia and other non-affective functional psychoses using a nationwide sample of people with epilepsy.
METHOD A record linkage study between a sample from the National Patient Register, consisting of 67,116 people with epilepsy, and the Danish Psychiatric Register identified all people with non-affective psychoses with onset after the first epilepsy diagnosis. The relation between risk of psychiatric disorder in people with epilepsy and the general Danish population was estimated.
RESULTS The incidences of the spectrum of non-organic non-affective psychosis, non-affective psychosis and schizophrenia were significantly increased both for men and women, even after exclusion of people diagnosed as suffering from a learning disability or substance misuse.
CONCLUSION This study supports the notion of an association between epilepsy and the risk of subsequent non-affective psychosis.