Brain-derived neurotrophic factor (BDNF) and bipolar disorder.

Brain-derived neurotrophic factor (BDNF) is deemed to be associated with the psychopathology of bipolar I disorder (BD). However, studies focusing on accuracy of BDNF levels to differentiate these patients from healthy controls (HCs) are scarce. Over a discrete twelve-year period, we investigated serum BDNF levels in patients with BD and compared them to age-, sex- and body mass index (BMI)-matched HCs. There were lower serum BDNF levels in 83 samples with BD than in 222 HCs samples (5.7 ± 4.2 ng/ml vs. 12.2 ± 7.5 ng/ml, F = 46.784). Pearson's correlation test showed significant positive correlations between Young Mania Rating Scale scores and the BDNF levels among 61 manic patients (γ = 0.339). The receiver operating characteristic curve analysis showed BDNF levels demonstrated a moderate accuracy of being able to differentiate BD patients from HCs (AUC = 0.801). The most adequate cut-off points of the BDNF level were 6.74 ng/ml (sensitivity = 82.0%, specificity = 63.9%). Our results support that BDNF demonstrated moderate accuracy to distinguish BD patients from HCs. In the future, greater samples would be required to prove these results.