Do antiepileptic drugs accelerate forgetting?

The majority of patients with epilepsy become seizure-free with antiepileptic drug therapy. However, seizures in approximately one-third of patients with epilepsy are difficult to treat with antiepileptic drugs and require high doses or polytherapy. High dosages increase the risk of cognitive side effects. We retrospectively investigated 162 patients with refractory temporal lobe epilepsy to determine whether the antiepileptic drugs carbamazepine, phenobarbital, and phenytoin affect the acquisition and retention of verbal and visual information. We found that patients with high serum levels of these antiepileptic drugs were selectively impaired in the retention but not acquisition of new information. Intelligence, age, duration of epilepsy, and seizure frequency were controlled for and were not factors in the observed results. There were no differences in favor of a certain drug with respect to memory functioning. Our results suggest that patients with refractory epilepsy with high serum levels of the antiepileptic drugs studied are at higher risk of accelerated forgetting.