Increased BDNF levels in long-term bipolar disorder patients

Introduction: Bipolar disorder (BD) is a prevalent, chronic and progressive illness. There is a growing body of evidence indicating that brain-derived neurotrophic factor (BDNF) plays an important role in the pathophysiology of BD. Objective: The aim of this study was to evaluate BDNF plasma levels in BD patients with long term illness in comparison with controls. Methods: 87 BD type I patients and 58 controls matched by age, gender and education level were enrolled in this study. All subjects were assessed by the Mini-International Neuropsychiatric Interview and the patients by the Young Mania Rating Scale and the Hamilton Depression Rating Scale. The plasma levels of BDNF were measured by ELISA. Results: On average, patients had suffered from BD for 23.4 years. In comparison with controls, BD patients with mania presented a 1.90-fold increase in BDNF plasma levels (p =. 001), while BD patients in remission presented a 1.64-fold increase in BDNF plasma levels (p =. 03). BDNF plasma levels were not influenced by age, length of illness or current medications. Conclusions: The present study suggests that long-term BD patients exhibit increased circulating levels of BDNF.