Effects of fluoxetine and venlafaxine on serum brain derived neurotrophic factor levels in depressed patients

Background: Several studies demonstrated that depressed patients had low serum BDNF levels which correlated with the severity of their depression, and antidepressant treatment increases levels of serum BDNF in depressed patients. It was speculated that agents acting on both noradrenergic and serotonergic transporters might have a greater influence on BDNF levels. The aim of our study was to determine effects of venlafaxine vs. fluoxetine on serum BDNF levels in depressive patients. Methods: Forty-three patients diagnosed as major depressive disorder according to DSM-IV are included in the study. Forty-three patients were randomized to take fluoxetine (22 cases) or venlafaxine (21 cases). Serum levels of BDNF were measured by ELISA at baseline and 6 weeks after the start of treatment. Results: Baseline levels of BDNF were not significantly different between the patient group and the controls. But male patients and the male controls showed statistical differences with respect to baseline BDNF levels. BDNF levels of the patient group did not change with treatment. Yet, the increase of BDNF levels was close to statistically significant in the fluoxetine group, whereas not significant in the venlafaxine group. There were no significant differences in baseline and 6th week BDNF levels between the responders and the non-responders. Conclusion: Further studies controlling for a wide variety of confounding variables are needed, which may help to reach a clear conclusion about the potential of BDNF as a biomarker for depression or as a predictor of antidepressant efficacy. (C) 2008 Elsevier Inc. All rights reserved.