BDNF and Anxiety: There is also mechanistic evidence supporting a beneficial effect of regular physical exercise—with subsequent increases in cardiorespiratory fitness—on cognition, notably through reductions in anxiety levels, increases in the neuroelectric activity of the cerebral cortex, increases in neurotrophins (e.g., brain-derived neurotrophic factor), and increases in hippocampal blood flow [13,14,15,16,17].