Low serum folate levels as a risk factor for depressive mood in patients with chronic epilepsy.

This study takes into consideration whether low serum folate levels may contribute to depressive mood in patients with chronic epilepsy. The serum folate levels and the score on the Self-Rating Depression Scale (SDS) were examined in 46 patients with chronic epilepsy. Patients with a score indicating at least minor depression on the SDS had a significantly lower serum folate level than patients with a normal score on SDS. There was a significant negative correlation between the serum folate levels and the SDS score. A serum folate level below 7.5 ng/ml was significantly associated with a pathological score on SDS. Because a serum folate level of 7.5 ng/ml is in the normal range for many laboratories, further studies using total plasma homocysteine as a sensitive measure of functional folate deficiency are required to elucidate the impact of folate metabolism on depressive mood in patients with chronic epilepsy.