BDNF and Cognitive impairment: The tricky relationship here is that we previously showed that non-low-intensity walking is associated with larger hippocampal volumes [1], and it is evident here that it is associated with WMH volume, but Otsuka et al. [41] explain that the subjects were patients with depressive symptoms and mild cognitive impairment, which affected the expression of the BDNF and may have reduced their association with WMH.