Elevated levels of serum, but not salivary, brain-derived neurotrophic factor following mild traumatic brain injury in collegiate athletes post return-to-play

Abstract

Brain-derived neurotrophic factor (BDNF) helps restore neuronal function following mild traumatic brain injury. BDNF levels can be obtained in blood serum and more recently in saliva. However, the relationship between serum and salivary BDNF is poorly understood—especially in relation to alterations in BDNF levels following mild traumatic brain injury. In this study, serum and salivary BDNF were collected from a sample of 42 collegiate student athletes. Half of the participants were recently cleared by a physician and/or an athletic trainer to return-to-play after experiencing a sports-related concussion. The other half had not experienced a concussion within the past year and were matched by age, sex, sport, and time of sample. Results suggest that incidences of depression, anxiety, and stress were all elevated in the concussion group, relative to the control participants. When controlling for stress-related negative affect, serum BDNF was elevated in the concussion group. However, there was no difference in salivary BDNF. Serum and salivary BDNF were uncorrelated across the entire sample. Yet, these measures of BDNF were correlated in the concussion group, but not the control group. In sum, serum BDNF is elevated in concussion post return-to-play; however, further research is needed to explore the utility of salivary BDNF following concussion.