A variety of factors contribute to cognitive dysfunction in persons with epilepsy, one of which is treatment with antiepileptic drugs (AEDs). The effects of AEDs appear to display a dose dependent relationship to cognitive functioning. Even more striking adverse effects on cognition are found as a result of AED polytherapy. Evaluation of the cognitive effects of AEDs in patients with epilepsy can easily be confounded by seizure effects, underlying cerebral injury, genetic, factors, and chronic impact of living with seizures. To limit the confounding cognitive effects of epilepsy, investigators have examined the cognitive effects of AEDs in healthy volunteers. Meador et al. (1995) have presented data demonstrating mild untoward effects of three common first line AEDs in a group of young healthy adults employing a randomized, double-blind, incomplete block crossover design. More than one-half of the neurocognitive dependent variables exhibited AED effects when compared with non-drug baselines. Studies of newer drugs have shown variable impairment with gabapentin and lamotrigine showing less impairment compared to the older, first-line drugs and to topiramate.