Serum protein levels of brain-derived neurotrophic factor and tropomyosin-related kinase B in bipolar disorder: effects of mood stabilizers.

AIM: In this study, we investigated serum protein levels of brain-derived neurotrophic factor (BDNF) and its receptor tropomyosin-related kinase B (TrkB) in patients with bipolar disorder.

METHODS

Over a 2-year period, 26 patients with bipolar I disorder (manic episode) and 56 healthy controls were recruited. The Young Mania Rating Scale scores of patients with bipolar mania were >26. Serum BDNF and TrkB protein levels were measured with ELISA kits.

RESULTS

Using ANCOVA with age adjustment, we found that there were no significant differences in serum BDNF protein levels between patients with bipolar mania and healthy controls (p = 0.582). In contrast, the serum TrkB protein level was significantly higher in bipolar mania patients than in healthy controls (p = 0.001), especially in women (p = 0.001). Of 26 patients with bipolar mania, 21 underwent a second measurement of serum BDNF and TrkB protein levels after a 4-week treatment with mood stabilizers. There were no significant changes in serum BDNF or TrkB protein levels.

CONCLUSION

These findings suggest that serum TrkB protein levels may play an important role in the psychopathology of bipolar mania. However, a larger sample size is needed to confirm these results.