BDNF relates to prefrontal cortex activity in the context of physical exercise

Exercise has been shown to support brain health, cognitive function, and increase levels of brain-derived neurotrophic factor (BDNF). While BDNF is known to support the central nervous system through improved brain metabolism, vasculature, neurotransmission and synaptic plasticity, the association between exercise-induced changes in BDNF concentrations and exercise-related cognitive improvements is still unclear. This study investigated the relationship between exercise-induced changes in plasma BDNF (pBDNF) and serum BDNF (sBDNF), and haemodynamic indicators of prefrontal cortex function in sedentary adults. Participants (n = 23, female = 7) were randomized into intervention (12-week cycling programme) and control groups (no intervention). Participants completed V̇O_2max tests to assess changes in fitness. pBDNF and sBDNF were measured pre- and post-V̇O_2max testing, and a battery of executive function and memory tasks were also conducted, alongside functional near-infrared spectroscopy (fNIRS) to assess haemodynamic changes in the prefrontal cortex activity. Changes were assessed using the correlation-based signal improvement (CBSI) method. Results indicated that participants in the exercise intervention group did not show increased levels of resting-state s/pBDNF levels at the end of the intervention; however, they did exhibit a significant exercise-induced increase in sBDNF at week 12. This increase was correlated with changes in V̇O_2max. Higher pBDNF levels and exercise-induced sBDNF were associated with a decrease in CBSI values in the frontopolar, dorsolateral and orbitofrontal prefrontal cortex during attention and inhibition tasks, but not during the memory task. These results suggest that increasing physical fitness can enhance BDNF transcription in response to acute bouts of exercise. This might, in turn, play a part in the modulation of neural function during executive tasks after acute exercise.