Serum Levels of Folate and Cobalamin Are Lower in Depressed Than in Nondepressed Hemodialysis Subjects

Abstract

The purpose of this study was to evaluate if there was a significant difference in serum and RBC folate or serum cobalamin levels in depressed and nondepressed subjects on hemodialysis (HD). A cross-sectional design was used in this study. Each subject's serum folate and cobalamin, and red blood cell (RBC) folate were measured. The Beck Depression Index II (BDI-II) was used to assess for depression. Subjects with scores of 10 or greater were considered depressed. Other laboratory, anthropometric, and demographic data were obtained from the subjects' medical records. To assess for significant differences (P < 0.05) in the laboratory values of the outcome variables between depressed and nondepressed subjects, t tests were performed on the groups' mean values. The study was conducted with patients in two dialysis centers in Texas. Seventy-three individuals undergoing HD for at least six months who met study inclusion criteria were solicited to participate in the study after the study was approved by the respective institutional review board. Depression and mental status of each subject were assessed using the BDI-II and the Folstein Mini-Mental State Exam, respectively. Serum folate, cobalamin, total homocysteine, and RBC folate were measured and mean values were evaluated for significant differences in the depressed and nondepressed groups. Of the subjects in this study, 43.8% had BDI-II scores > 10 indicating depression. The nondepressed subjects had significantly higher mean serum folate (281 +/- 649 vs. 52 +/- 137 ng/mL), serum cobalamin (1162 +/- 1014 vs. 757 +/- 463 pg/mL), and RBC folate (1433 +/- 1757 vs. 810 +/- 654 ng/mL) levels than did depressed subjects. In the nondepressed group, 39% of subjects were taking a supplement containing 35-42 mg folacin and 7 mg cobalamin per week while only 9.1% of depressed subjects were taking a vitamin containing these levels of B vitamins. The group means were not significantly different for age, months on HD, body mass index, erythropoietin/kg body weight, total homocysteine, hemoglobin, albumin, or ferritin. As with the general population, lower serum folate, RBC folate, and serum cobalamin levels were found in depressed as compared to nondepressed subjects on HD. Plasma levels of these vitamins may be one of many factors related to depression, but larger studies with stronger designs are needed to confirm the results of this study.