NGF and depressive symptom measurement: Nerve growth factor (NGF) played an important physiological role in the regulation of hypoxic-ischemic adaptation of central nervous system tissues or cells mainly by binding its high-affinity receptor TrkA. Abnormal expression of NGF and its receptors could cause diabetes, depression, Alzheimer’s disease and other diseases (Li et al., 2005; Wiener et al., 2015).