The study, “Psychotic disorders induced by antiepileptic drugs in people with epilepsy,” was published in the journal Brain.
Epilepsy is one of the most common neurological disorders and ranks as the second leading neurological cause of reduced disability-adjusted life-years. The average incidence of epilepsy each year in the U.S. is estimated at 150,000 or 48 for every 100,000 people.
Patients with epilepsy have increased vulnerability to psychiatric co-morbidity, including psychotic disorders, imposing additional burdens on patients. Among the psychotic disorders in epilepsy, antiepileptic drug (AED)-induced psychotic disorder (AIPD) represents a serious adverse drug reaction.
Prevalence of AIPD has been reported to range from 1.0 percent to 8.4 percent in clinical trials of AEDs.
Patrick Kwan from the Department of Medicine and Neurology at the University of Melbourne in Australia and his colleagues reviewed medical records from January 1993 to June 2015 of all epilepsy patients with a diagnosis of a psychotic disorder at the Royal Melbourne Hospital.
The researchers compared patients with AIPD with patients with psychotic disorders who were not associated with the use of antiepileptic drugs evaluated over the same time period (non-antiepileptic drug-induced psychotic disorder group).
Overall, researchers reviewed the medical records of 2,630 patients with epilepsy. Of these, 98 (3.7 percent) had a psychotic disorder, and among these, 14 (14.3 percent) had a diagnosis of AIPD.
Ten patients (76.9 percent) in the non-antiepileptic drug induced psychotic disorder group were female. The percentage of temporal lobe involvement (a type of epilepsy) was superior in the non-antiepileptic drug induced psychotic disorder group (69.2 percent versus 38.1 percent).
Use of an antiepileptic drug called Keppra (levetiracetam) was higher in the AIPD group (84.6 percent compared to 20.2 percent) and the use of Tegretol (carbamazepine, an anti-epileptic drug) was superior in the comparator group (15.4 percent compared to 44.0 percent).
The researchers then evaluated potential factors related with AIPD and found that the statistically significant factors were female gender, temporal lobe involvement and use of Keppra, and found a negative relationship with Tegretol.
“In this study, the psychotic symptoms induced were not associated with high dose or fast titration of the offending agents, suggesting that there was individual susceptibility in terms of AIPD. Therefore investigation of genetic markers of AIPD should be the considered for the future studies,” the researchers wrote.
“Disorganized behaviors and abnormal disorganized thinking were predominant symptoms of AIPD. AIPD had an overall better outcome than that of other psychotic disorders in people with epilepsy,” they wrote.