Y Yalçın Arslan, D Ceylan, A Ozerdem, H Resmi, D Cımrın, Z Tunca

Dokuz Eylul University, Izmir, Turkey

Objective: Mood disorders are frequently associated with dysfunction of hypothalamic-pituitary-thyroid (HPT) axis (Handric et al., 1998). BDNF, as a key mediator for neuroplasticity was consistently shown to be decreased in bipolar disorder (Cunha et al 2006). Thyroxine increases BDNF expression in the developing brain whereas it downregulates BDNF in adult neurons in rats (Shulga and Rivera 2012). We aimed to investige inter- action between BDNF and thyroid hormons in bipolar disorder.

Methods: One hundred and eight adult bipolar disorder patients (euthymia = 37, mania/depression = 71) and 61 healthy volunteers were enrolled in the study. All participants were evaluated with Structured Clinical Interview for DSM-IV-TR (SCID-I). Serum BDNF, TSH, fT3 and fT4 levels were measured using ELISA assays. Statistical analysis was done using SPSS 15.0 (One vay ANOVA, post hoc Bonferonni, univariate analysis, after log trans- formation of values and Spearman correlation test).

Results: The mean serum BDNF levels (±SD) of patients in manic/ depressive episode (3921.80 ± 1763.71) were significantly lower compared to healthy volunteers (5646.23 ± 2586.99 pg/mL) (p = 0.013). Euthymic patients (6661.46 ± 3190.36 pg/mL) did not differ from healthy volunteers (p = 1.000). The mean serum TSH, fT3 and fT4 levels did not differ between the groups. BDNF levels negatively correlated with fT3 levels only in manic/depressed patients (n = 44, r = – 0.330, p = 0.029), but not in euthymcs. BDNF levels or thyroid hormones did not interact with age, serum level or duration of lithium use in those patients who were using lithium.

Discussion: Our findings suggested a down-regulation of BDNF by thyroxin in adult bipolar disorder patients in manic/depressive episode.

Keywords: bdnf, thyroid hormones, bipolar disorders

Bipolar Disorders © 2013 John Wiley & Sons A/S, Bipolar Disorders, 15 (Suppl. 1) 104–155