Background Patients with epilepsy who use anticonvulsants frequently show low levels of folate and vitamin B12 and high levels of homocysteine. Patients with bipolar disorder use some anticonvulsants as mood stabilisers.
aim To determine whether some anticonvulsants lower folate and vitamin B12 and raise homocysteine levels.
method Systematic literature search to determine the relation between the anticonvulsants valproic acid, carbamazepine, lamotrigine and topiramate on the one hand and blood levels of folate, vitamin B12 and homocysteine on the other hand.
results The vast majority of studies in adults and children showed a correlation between use of anticonvulsant carbamazepine and decrease of the folate level. Hardly any of the studies that examined the effect of valproic acid on folate levels found a correlation. There was next to no evidence of a correlation between the use of carbamazepine and a low vitamin B12 level in adults or children. In adults and children the use of valproic acid was found to correlate with a higher vitamin B12 level. Nearly all studies found an increase in homocysteine in adults and children using carbamazepine. Among the users of valproic acid, it was only children who showed a clear association with a rise in homocysteine level. The results for adults were contradictory. We were unable to make any clear statement about topiramate or lamotrigine because there have been very few publications about these anticonvulsants.
conclusion In adults and children with epilepsy use of carbamazepine is associated with a decrease of folate, valproic acid with a rise in the vitamin B12 level, and carbamazepine with an increase in homocysteine. Valproic acid showed only in children an association with the rise of the homocysteine level. Psychiatrists may find it advisable to control the levels of folate and homocysteine in adults and children who are taking carbamazepine and to measure homocysteine level in children taking valproic acid.