Effects of paroxetine or milnacipran on serum brain-derived neurotrophic factor in depressed patients

Brain-derived neurotrophic factor (BDNF) is an important member of the neurotrophin family of growth factors, abundant in the brain and periphery. Researchers have reported that serum BDNF levels in drug-free depressed patients are lower than those of healthy controls, and have proposed that these low levels might reflect a failure of neuronal plasticity in depression. In the present study, we investigated the effects of paroxetine, an SSRI, and milnacipran, an SNRI, on serum BDNF levels in depressed patients. Serum levels of BDNF were measured by ELISA before, 4 weeks, and 8 weeks after the start of treatment with antidepressants. Forty-two patients were randomly administered paroxetine (21 cases) or milnacipran (21 cases). A negative correlation was found between serum BDNF levels and baseline Ham-D scores. The response and remission rates for each drug were not significantly different. Serum BDNF levels in responders were significantly increased 2.6- and 1.8-fold 8 weeks after treatment with paroxetine or milnacipran, respectively. These results suggest that both drugs improve the depressive state by increasing BDNF levels.