Serum brain-derived neurotrophic factor (BDNF) at rest and after acute aerobic exercise in major depressive disorder.

Physiological mechanisms of an anti-depressive effect of physical exercise in major depressive disorder (MDD) seem to involve alterations in brain-derived neurotrophic factor (BDNF) level. However, previous studies which investigated this effect in a single bout of exercise, did not control for confounding peripheral factors that contribute to BDNF-alterations. Therefore, the underlying cause of exercise-induced BDNF-changes remains unclear. The current study aims to investigate serum BDNF (sBDNF)-changes due to a single-bout of graded aerobic exercise in a group of 30 outpatients with MDD, suggesting a more precise analysis method by taking plasma volume shift and number of platelets into account. Results show that exercise-induced increases in sBDNF remain significant (p < .001) when adjusting for plasma volume shift and controlling for number of platelets. The interaction of sBDNF change and number of platelets was also significant (p = .001) indicating larger sBDNF-increase in participants with smaller number of platelets. Thus, findings of this study suggest an involvement of peripheral as well as additional - possibly brain-derived - mechanisms explaining exercise-related BDNF release in MDD. For future studies in the field of exercise-related BDNF research, the importance of controlling for peripheral parameters is emphasized.