COGNITIVE SIDE-EFFECTS OF PHENYTOIN COMPARED WITH CARBAMAZEPINE IN PATIENTS WITH LOCALIZATION-RELATED EPILEPSY

In continuation of an earlier study of our group (Neurology, 43 (1) (1 993) 41-51), we present the results of an investigation of the adverse effects of carbamazepine versus phenytoin on cognitive function. Two groups of twenty-five patients are compared in an open, parallel group and non-randomized clinical investigation: a group of patients on car bamazepine (CBZ) monotherapy versus a group of similar size on phenyto in (PHT) monotherapy. The two groups do not show significant differenc es on variables that could confound the comparison of drug-specific ad verse effects: age, gender, intelligence, type of epilepsy, seizure ty pe, seizure frequency, EEG focus and age at onset of the epilepsy. All patients were investigated with a comprehensive neuropsychological te st battery ('FePsy'), assessing the cognitive domains of 'speed factor s', memory and attention. The results show lower performance in the PH T group compared to the CBZ group on all tests measuring motor speed. Additionally, there is evidence that PHT also affects the speed of cen tral 'higher cortical' processing systems. Our investigation also show s slower performance in tasks that measure speed of information proces sing ('mental speed'). The other investigated areas, i.e. short-term m emory, long-term (verbal and non-verbal) memory and selective attentio n, do not reveal statistically significant differences between the two groups. These results reconfirm that patients on PI-IT may suffer fro m cognitive side-effects even when the medication is sufficiently cont rolled and the drugs are given within the assumed therapeutical interv al.