To investigate the change rule of serum brain-derived neurotrophic factor (BDNF) concentration at different time points in patients with traumatic brain injury (TBI) of different degrees and the relationship between serum BDNF concentration and prognosis.

One hundred and forty-nine TBI patients admitted to Department of Neurosurgery, Qinghai Provincial People’s Hospital from October 2016 to October 2018 were analyzed. According to GCS scores at admission, the patients were divided into mild group (13-15 scores) 52 cases, moderate group (9-12 scores) 49 cases, and severe group(3-8 scores) 48 cases. The control group consisted of 35 healthy subjects. The dynamic change relationship of BDNF in different injury groups at different time points and the relationship between BDNF and control group were analyzed. The prognosis of TBI patients was evaluated by GOS scores 3 months after injury. They were divided into good prognosis group (4-5 scores) 98 cases and poor prognosis group (1-3 scores) 51 cases. The difference of serum BDNF concentration between the two groups at different time points was compared, and the correlation between serum BDNF value at different time points and the GCS scores at admission and the GOS scores 3 months after injury were analyzed.

(1) The concentrations of serum BDNF in the mild, moderate and severe groups on day 1, 7 and 14 were compared with those in the control group, and had no significant statistical difference on day 1 (P>0.05). The concentrations of serum BDNF in the other groups and at different time points were significantly lower than those in the control group (P=0.001); (2) The concentration of serum BDNF in the moderate and severe groups were lower than those in the mild group on day 1, 7 and 14 (P=0.001). The serum BDNF concentrations in severe group were lower than those in medium group on day 1, 7 and 14 (P=0.001); (3) After 3 months’ follow-up, there was a significant difference between poor prognosis group and good prognosis group at each time point (P=0.001); (4) There was a positive correlation between the serum BDNF levels and the GCS scores in TBI patients on day 1, 7 and 14 after injury. The score was also positively correlated with GOS 3 months after injury.

The changes of serum BDNF concentrations in patients with TBI are related to different injuries and prognosis. It can be used as one of the indicators for early diagnosis of TBI severity and prognosis.