Adding a low dose atypical antipsychotic drug to an antidepressant induced a rapid increase of plasma brain-derived neurotrophic factor levels in patients with treatment-resistant depression.

Only two-thirds of depressive patients respond to antidepressant treatment. Recently, addition of an atypical antipsychotic drug to ongoing treatment with an antidepressant has been considered effective and well-tolerated. In the present study, we examined the effects of various atypical antipsychotic drugs as adjuvant to antidepressants, including selective serotonin reuptake inhibitors (SSRIs), serotonin noradrenaline reuptake inhibitors, tricyclic antidepressants and mood stabilizers, on plasma BDNF levels in refractory depressed patients. Forty-five patients who met the DSM-IV criteria for major depressive disorder (n=31) or bipolar disorder (10 with bipolar I, 4 with bipolar II) were enrolled in the study. Twenty-one were male and 24 were female, and their ages ranged from 28 to 71 (mean+/-SD=49+/-12) years. Plasma BDNF levels were measured using a sandwich ELISA. The plasma BDNF levels in responders (those showing a decline in HAM-D scores of 50% or more) were significantly increased 4weeks after the administration of each atypical antipsychotic drug, while the levels in non-responders were not changed. Furthermore, there was a significant correlation between the changes in HAM-D scores and the changes in plasma BDNF levels. These results suggest that adding an atypical antipsychotic drug to ongoing treatment with an antidepressant or mood stabilizer is useful and well-tolerated for refractory depressed patients, and the efficacy of atypical antipsychotics as an adjuvant might involve an increase of plasma BDNF levels.