Inclusion Criteria:  Athletes and patients with traumatic brain injury  Age ≥ 18 and ≤ 80 years old with independent behavior ability or authorized legal representative. Have a clear history of repetitive mild TBI, concussion or subconcussion. The most recent head injury occurred 3 months ago.  Healthy Volunteers  Age ≥ 18 and ≤ 80 years old with independent behavior ability. No history of repetitive mild TBI, concussion or subconcussion. Fully understands the nature of the study, and voluntarily participates and signs the informed consent.  Exclusion Criteria:  Athletes and patients with traumatic brain injury  Pregnant or lactating women. History of other neurological diseases. History of tumors, hematological diseases, severe cardiopulmonary diseases, hepatic failure or renal failure. Have participated in clinical trials in the past four weeks. The investigator believes that not appropriate for inclusion.  Healthy Volunteers  Pregnant or lactating women. History of TBI or other neurological diseases. History of tumors, hematological diseases, severe cardiopulmonary diseases, hepatic failure or renal failure. Have participated in clinical trials in the past four weeks. The investigator believe that not appropriate for inclusion.