EEG changes induced by carbamazepine therapy at rest and during mental processes.

The effects of carbamazepine (CBZ) on EEG background activity have been studied, at rest and during mental processes, in 18 epileptic patients suffering from focal epilepsy and starting antiepileptic treatment for the first time. The EEGs were recorded before and after CBZ therapy, at rest with eyes closed (EC), during blocking reaction (BR), fixation (FIX) and mental arithmetic (MA) tasks, and then evaluated by spectral analysis. All data underwent statistical evaluation utilizing the ANOVA and correlation coefficient. The following parameters were evaluated: mean absolute and relative power and mean frequency. The results have shown that CBZ induced a significant increase of slow activity at rest with EC, which was represented by delta potentials, and was correlated with CBZ plasma levels. In evaluating the different cortical activation patterns, a decrease of the alpha reactivity was noted during BR and FIX, while a significant increase of beta activity was observed during the performance of all tasks. The relationship between the increased beta power, possibly reflecting an increase of cognitive activity for processing information, and the lack of a significant decrease of alpha activity are discussed.