Similarly, Dawood et al. (2007) reported a positive internal jugular veno-arterial BDNF plasma concentration gradient as well as higher BDNF levels in plasma obtained from internal jugular venous blood than in plasma obtained from brachial arterial blood, indicating that efflux of BDNF from the brain contributes to peripheral BDNF concentrations at rest in patients with major depressive disorder. Here, BDNF is linked to major depressive disorder.