Serum brain-derived neurotrophic factor levels and personality traits in patients with major depression

BACKGROUND Brain-derived neurotrophic factor (BDNF) is a member of the neurotrophin family of growth factors. Previous studies have demonstrated lower serum BDNF levels in patients with major depressive disorder (MDD) and reported an association between BDNF levels and depression-related personality traits in healthy subjects. The aim of the present study was to explore for a possible association between peripheral BDNF levels and personality traits in patients with MDD. METHODS In this cross-sectional study, a total of 123 inpatients with MDD (Diagnostic and Statistical Manual for Mental Disorders, 4th edition) at the Juntendo University Koshigaya Hospital were recruited. Serum levels of BDNF were measured. Personality traits were assessed using the 125-item short version of the Temperament and Character Inventory (TCI). RESULTS Multiple regression analysis adjusted for age, sex, body mass index, dose of antidepressant, and depression severity showed that TCI Self-Directedness (SD) scores were negatively associated with serum BDNF levels (β = -0.23, p = 0.026). CONCLUSIONS MDD patients who have low SD did not show the reduction in serum BDNF levels that is normally associated with depressive state. Our findings suggest that depression-related biological changes may not occur in these individuals.