Cognitive effects of topiramate revealed by standardised low-resolution brain electromagnetic tomography (sLORETA) of event-related potentials
OBJECTIVE
To evaluate the effect of topiramate (TPM) on event-related potentials (ERPs) in patients with epilepsy.


METHODS
Neuropsychological tests and ERP study using auditory oddball paradigm were conducted before and after treatment with TPM in drug-naive epilepsy patients. To detect target brain regions in which ERP changed during the cognitive task, cortical current densities of ERP components were analysed using standardised low-resolution electromagnetic tomography (sLORETA).


RESULTS
Neuropsychological tests (n=18 patients) showed that TPM significantly decreased the score in digit span, Corsi block and Controlled Oral Word Association word fluency. Repeated-measures analysis of variance of ERP data (n=13 patients) revealed that P2 amplitude was significantly increased at Fz electrode following treatment with TPM. Statistical non-parametric map of sLORETA between pre- and post-TPM ERPs revealed that current density of P200 component was significantly reduced by TPM in bilateral parieto-occipital, temporolimbic and dorsolateral right prefrontal regions.


CONCLUSIONS
Our findings suggest that TPM affects selective brain regions which may be related to cognitive side effects.


SIGNIFICANCE
Source localisation of ERPs can be helpful in identifying target brain regions for the cognitive side effects of anti-epileptic drugs.