Background: Depression has been associated with decreased blood BDNF concentrations; but it is unclear if low blood BDNF levels are a state or a trait marker of depression.
Methods: We investigated blood BDNF concentrations in a twin population including both subjects highly predisposed and protected against affective disorder. Whole blood assessed for BDNF concentrations and correlated to risk status, neuroticism, and number of stressful life events.
Results: Between the groups, we found no significant difference in whole blood BDNF levels. Women at high-risk for depression who had experienced three or more recent stressful events (n=26) had decreased whole blood BDNF levels compared to high-risk women with two or less recent stressful events (n=35), 21.6+/-7.0 vs. 18.5+/-4.1 ng/ml, respectively, (p<0.05). No such association was found in low-risk women or in men. In men, however, low neuroticism scores and two or less recent stressful events were associated with decreased whole blood BDNF levels (n=50, p<0.05).
Limitations: The cross-sectional design limits the possibility of drawing firm conclusions on causatility of the findings.
Conclusion: The genetic risk of developing depression does not translate directly into whole blood BDNF levels. In females who are genetically disposed for depression and subjected to recent stressful life events whole blood BDNF levels are lower.