RESUMO
INTRODUCTION: Phenytoin and carbamazepine were the antiepileptic drugs most frequently used in Mexico and throughout the world. Epileptic patients who take these drugs have a variety of collateral effects including the decrease of folates plasmatic level. Low seric folic acid concentration has been associated with a decline in cognitive functions. The administration of a combined treatment with folic acid could ameliorate these difficulties. OBJECTIVE: To describe the effect of the folic acid in the cognitive function in epileptic patients who take phenytoin and carbamazepine. METHODS: We chose patient who have epilepsy and that are being treated with phenytoin, carbamazepine or both and formed two groups. The study group was treated with a daily dose of 5 mg of folic acid and the control group was administered placebo for a period of six months, with nine patients in each group of same age, sex, education level, epilepsy's evolution, frequency of seizures, EEG abnormalities and antiepileptic drugs plasma levels. We registered data at the beginning (basal) and at the end of the study. RESULTS: Measurements of basal folic acid plasma levels in both groups were under the referential value. The neuropsychological assessment at the beginning (Mini-Barcelona test) showed a deficit in the verbal memory skills in both groups. After six months of treatment with folic acid (study group), the folic acid plasma level was 12.2 mg/mL (p < 0.01) higher than the basal value. Verbal memory test has improved with respect to the basal value (p < 0.05). The numbers of seizures and the plasma levels of the antiepileptic drugs remained unchanged. On the other hand, the group treated with placebo did not improve. CONCLUSION: Treatment with folic acid is safe and without side effects, it improved the cognitive function in patients with epilepsy treated with phenytoin and carbamazepine.