Plasma folate and homocysteine levels may be related to interictal "schizophrenia-like" psychosis in patients with epilepsy.

Genetic and clinical data suggest that folate and homocysteine may play a role in the pathogenesis of psychiatric disorders. The total plasma homocysteine level is a sensitive measure of a functional folate deficiency. We thus investigated whether a functional folate deficiency and/or elevated levels of plasma homocysteine may be related to interictal "schizophrenia-like" psychosis (interictal psychosis ) of epilepsy. We studied the plasma folate, vitamin B12, and homocysteine levels of 32 age- and sex-matched epileptic patients with or without interictal psychosis. Each group included 25 localization-related epilepsies and 7 generalized epilepsies. The epileptic patients with interictal psychosis had significantly lower folate levels and higher homocysteine levels than those without interictal psychosis. There were no significant differences in the vitamin B12 levels between the two groups. The present study suggests that low plasma folate and high plasma homocysteine levels may be related to the pathophysiology of interictal psychosis of epilepsy. In future studies, we should investigate whether folate supplementation, in addition to antipsychotics, might play a beneficial role in the treatment of interictal psychosis in epileptic patients. Furthermore, the present findings should be confirmed by prospective longitudinal studies in a larger group of patients with epilepsy.