No Association between the Response to the Addition of an Atypical Antipsychotic Drug to an SSRI or SNRI and the BDNF (Val66Met) Polymorphism in Refractory Major Depressive Disorder in Japanese Patients

Objective: This study examined the association between the brain-derived neurotrophic factor (BDNF) (Val66Met) polymorphism and the response to the addition of an atypical antipsychotic drug to a selective serotonin reuptake inhibitor (SSRI) or seroto-nin-norepinephrine reuptake inhibitor (SNRI) in treatment-refractory depression. Methods: The study enrolled 64 patients meeting the Diagnostic and Statistical Manual of Mental Disorders-IV criteria for major depressive disorder who were treated with at least two courses of a single antidepressant, but who had Hamilton Depression Rating Scale (HAMD-17) scores ≥15 points that were reduced less than 50 % over at least a 4-week treatment period. There were 24 males and 40 females (age range 27-68 years; mean±SD, 48±13 years). The patients ' clinical improvement was eval-uated using the HAMD-17. Patients with at least a 50 % decrease in the HAMD-17 score were defined as responders. Serum BDNF levels were assayed using enzyme-linked immunosorbent assays and the presence of the BDNF (Val66Met) polymorphism was determined using the TaqMan genotyping assay. Results: No correlation was found between the BDNF (Val66Met) polymorphism and a positive response to adding an atypica