Phenytoin and carbamazepine: differential effects on cognitive function.
This review summarizes the studies on the cognitive side-effects of two important antiepileptic drugs: phenytoin and carbamazepine. A large literature database was compiled through the DIMDI computer database and the inspection of recent reviews. Only scientific articles published in peer-reviewed journals during the last 25 years were selected. Of the 358 potentially relevant papers on cognitive effects of AEDs, a total of 16 studies have been found that have studied both carbamazepine and phenytoin. After excluding studies with designs that do not permit valid inferences regarding the cognitive effects of AEDs, only five studies remained. The evaluation of these studies reveal that our current knowledge allows us to draw conclusions about the cognitive side-effects of phenytoin and carbamazepine only with great caution. The claim in reviews that 'both drugs have an impact on cognitive function, PHT to a larger degree than CBZ' is simply not supported by valid 'high quality' data. The same is true for the overall conclusion in more recent reviews that 'drug-induced cognitive effects of these AEDs on cognitive function are probably mild or even negligible'. Apparently, the only information that we have is that the differential impact of PHT and CBZ on cognitive function is not extremely different. No conclusive and reconfirmed data are available on the absolute effects of CBZ and PHT (differences between the two drugs and a no-treatment condition). Our review summarizes some recommendations for future studies.
Aldenkamp
A P
AP
Department of Neuropsychology, Meer & Bosch Epilepsy Centre, Heemstede, The Netherlands.
Vermeulen
J
J
D002220:Carbamazepine / Q000009:adverse effects* / Q000627:therapeutic use; D002986:Clinical Trials as Topic; D003071:Cognition / Q000187:drug effects*; D004359:Drug Therapy, Combination; D004827:Epilepsy / Q000188:drug therapy*; D006801:Humans; D009483:Neuropsychological Tests; D010672:Phenytoin / Q000009:adverse effects* / Q000627:therapeutic use; D012307:Risk Factors
D002220:Carbamazepine; D010672:Phenytoin