BDNF mRNA expression of peripheral blood mononuclear cells was decreased in depressive patients who had or had not recently attempted suicide

Background: Recent reports have suggested a pathophysiological role for brain-derived neurotrophic factor (BDNF) in major depression and suicide. We evaluate BDNF mRNA in peripheral blood mononuclear cells (PBMCs) of patients with major depression who had or had not recently attempted suicide. Methods: BDNF mRNA expression was examined in PBMCs of 30 major depressed patients without recent suicide attempts, 30 major depressed patients with recent suicide attempts, and 30 healthy controls. All patients were diagnosed with major depressive disorder (MDD) and they were either medication-naïve or medication-free. BDNF mRNA expression was measured using real-time quantitative PCR. Results: BDNF mRNA expression was significantly decreased in PBMCs of MDD patients, with or without a history of suicide attempts, when compared with healthy controls (Z =-5.233, p < 0.001). Suicidal MDD patients had more decrease in BDNF mRNA expression (χ² = 45.881, df = 2, p < 0.001). Limitations: The sample size of the present study was relatively small. Although suicidal MDD patients had higher HDRS scores than non-suicidal patients, the comparison of BDNF mRNA between them could not be adjusted for HDRS score. Conclusions: Our study suggests that the BDNF mRNA expression is reduced in PBMCs of patients with major depression. This alteration of BDNF mRNA expression was noteworthy in recent suicide attempters. Such a decrease in BDNF mRNA might be associated with BDNF decrease in serum or plasma, and might also correspond to a BDNF decline in the brains of MDD patients.