Phenytoin and cognitive function: Effects on normal volunteers and implications for epilepsy

Abstract

Despite the widespread use of phenytoin in the treatment of epilepsy, few studies have examined its effects on cognitive functioning. The results of an investigation into the effects of phenytoin on the performance of non-epileptic volunteers, in a series of specially designed psychological tests are reported. Subjects received placebo or phenytoin 300 mg/day for 2 wk in a double-blind crossover design and phenytoin serum levels were measured. The results demonstrate a deleterious effect of phenytoin upon several important aspects of cognition, including memory, concentration, and mental and motor speed.