Serum brain-derived neurotrophic factor level in dysthymia: a comparative study with major depressive disorder

In this present work, it is aimed to demonstrate BDNF serum concentrations in patients with dysthymia and to compare them with BDNF serum concentrations in patients with major depressive disorder and healthy subjects. The study was carried out in Celal Bayar University Hospital, Manisa, Turkey. Seventeen patients with dysthymia, 24 patients with major depressive disorder and 26 subjects without any psychiatric diagnosis and any psychiatric treatment were included in the study. The severity of depression was assessed with 17-item HAM-D. All subjects were asked to give their written consent. Blood samples were collected at baseline. Serum BDNF was kept at -70 degrees C before testing, and assayed with an ELISA Kit (Promega; Madison, WI, USA), after dilution with the Block and Sample solution provided with the kit. The data were subjected to the analysis of variance. The BDNF serum concentrations of the dysthymia group (mean=28.9+/-9.2 ng/ml) were significantly higher than that of the major depressive disorder group (21.2+/-11.3 ng/ml) (p=0.002), and it was not different from the level of the control group (31.4+/-8.8 ng/ml). BDNF serum concentrations and HAM-D score did not have any significant correlation in the dysthymia and major depression groups (r=-0.276, p=0.086). The low level of BDNF in patients with dysthymic disorder seems to point out that BDNF changes in mood disorders are state-dependent and vary according to the severity of depressive episodes.