Increase of serum BDNF level in depressive patients identifies therapy response and correlates with mood improvement

Depression is one of the most prevalent forms of mood disorders. Compelling evidence suggests that these are characterized by reduced neuronal plasticity, brought about by exposure to stress. There is good agreement considering key proteins such as brain-derived neurotrophic factor (BDNF), as a central player for the effects of stress on brain function, plasticity and psychopathological implications. Still, there is a high non-responder rate in antidepressant therapy, which explains the need to find reliable predictors for adequate treatment. Previous studies revealed that plasma and serum BDNF levels in depressed patients were significantly lower than in healthy controls. To investigate the association between BDNF serum levels and treatment outcome, blood was drawn from 28 patients with a major depressive episode (DMS-IV, ICD-10) that participated in a doulbe-blind placebo controlled treatment study. All patients were treated with a stable mirtazapine monotherapy. Partial sleep deprivation (PSD) was performed after one week. After PSD, serum of depressive patients exhibited a significantly (p < 0.01) increased BDNF content. Enhanced BDNF serum levels after PSD were prominent in all patients identified as responders after 2 weeks of follow up. Furhtermore we were able to show that high BDNF serum levels after PSD reflected mood improvement, and increased relaxation.We conclude that an increase in BDNF is linked to positive treatment response.