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Epilepsy drugs may induce some psychotic disorders, study says

Epilepsy patients are already at increased risk for psychiatric conditions and psychosis, though drugs used to treat the condition have been suspected of increasing risk for psychotic episodes, and a new study shows this may be true.

Researchers at the University of Melbourne found patients on antiepileptic drugs were at greater risk for psychotic episodes, which appear to subside as patients are eased off the drugs, according to a study recently published in the journal Brain.

A 2005 study suggested the incidence of schizophrenia and psychosis was between 2.5 times and 3 times higher in epilepsy patients than in the general population.

Clinical trials for some antiepileptic drugs have also shown psychotic episodes to be among the potential side effects for up 8.4 percent of participants, though researchers in Melbourne had not seen a study looking exclusively at the prevalence of episodes among patients being treated with the drugs.

For the new study, researchers identified 98 epilepsy patients — 53 male and 45 female — who had experienced psychotic disorders. Among these, 14 patients, or 14.3 percent of participants, had psychosis classified as associated with epilepsy treatment, while the rest had psychosis or a psychiatric condition tied to their condition but not a medication.

Overall, 1 out of every 7 epilepsy patients have a psychotic disorder tied to epilepsy treatment, with women and patients with temporal lobe epilepsy more likely to develop a disorder linked to their drug treatment.

The drug most commonly used among patients who experienced psychosis was levetiracetam, which more than half the 14 patients were taking, with the others being treated with lamotrigine, topiramate and valproate. In most cases, the researchers report psychotic symptoms resolved after patients were eased off the drugs.

Future research is needed to identify genetic predictors of psychosis in epilepsy patients because while the drug triggered the response, individual susceptibility is suspected to be a major factor for psychotic episodes, researchers write in the study.