BDNF and depressive symptom measurement: Abnormalities in BDNF, glutamate receptors, VEGF signaling, and long-term potentiation (LTP) pathways also contribute to the pathophysiological progression of depression by affecting neuroplasticity and neurogenesis (Duric et al., 2010; Yoshii and Constantine-Paton, 2010; Gormanns et al., 2011).