Associations between Serum Brain-Derived Neurotrophic Factors and Bipolar Disorder

Abstract Background: Brain-derived neurotrophic factor (BDNF) is known related to the psychopathology of bipolar disorder. However, the results of the relationship between BDNF levels and bipolar disorder were inconsistent. In this study, we aimed to investigate the relationship between BDNF levels, the different phases and clinical phenotypes of bipolar disorder. Methods: Over a 4-year period, bipolar patients in different disease phases, including mania phase, depressive phase and remission, were recruited. All participants had peripheral blood drawn to analyze the serum BDNF levels. We also investigated the relationships between serum BDNF levels, violence, suicidal behavior and Young Mania Rating Scale score (YMRS) before and after 4-week treatment. Results: A total of 102 participants in different disease phases, including acute mania (n=44), acute depressive episode (n=20) and remission (n=38) of bipolar disorder were invited for this study. The serum BDNF levels of patients with acute mania or depressive phases were significantly lower than bipolar patients in remission phases using ANCOVAs with age and sex adjustment (mania: p=0.013, depression: p=0.003, respectively). Bipolar mania patients with violence had lower BDNF levels than those without violence (p=0.025). Among 42 followedup patients, increased BDNF level from baseline was noted after one-month treatment, but there is not statistically significant by means of paired t test (mania: p=0.845 and depression: p=0.931, respectively). Conclusions: Our study found that lower serum BDNF levels are strongly associated with the depressive and manic phase of bipolar disorder than remission phase. In addition, bipolar mania patients with violence had lower BDNF levels than those without violence. In the future, it needs a large sample to prove these results.