Brain-derived neurotrophic factor: Biopsychosocial correlates and exercise response in mild traumatic brain injury

Abstract

Recovery from mild traumatic brain injury (mTBI) is a dynamic, complex process, and pre-clinical research highlights brain-derived neurotrophic factor (BDNF) as an important mediator in functional and pathophysiologic outcomes. Although BDNF appears to also be a significant factor in recovery in humans, its role is less understood. Our purpose was (1) to examine the association of serum and platelet-poor plasma concentrations of BDNF to relevant biopsychosocial outcomes of mTBI recovery (i.e., neurocognitive performance [attention, processing speed, memory, executive functioning], sleep, balance, mood, and self-reported symptoms) and (2) to assess BDNF response to a single-session of aerobic exercise (40 minutes of stationary cycling at 65%–75% maximum heart rate). There were 36 participants (ages 18–40; 19 male, 17 female) in 2 groups: (1) mTBI participants (n = 26) who were 14–25 days post-injury were randomized to either aerobic or non-aerobic exercise (low intensity stretching) and (2) demographically-matched, non-injured participants (n = 10) who participated in a single session of aerobic exercise. Results indicate that serum BDNF concentration has significant ( p = 0.05), inverse relationships with both sleep dysfunction and state levels of anxiety. No significant association between exercise type and serum BDNF was found, but there was a small to medium effect size (= 0.08) for increased plasma BDNF after aerobic exercise in mTBI vs non-injured participants. Overall, peripheral BDNF concentrations are poorly correlated, which suggests they reflect different tissue sources. Serum BDNF was more sensitive to select biopsychosocial outcomes, particularly sleep quality and anxiety, regardless of injury status. Additionally, aerobic exercise may play a role in enhancing platelet-poor plasma BDNF response in the post-acute period after mTBI.