BDNF and major depressive disorder: Deficits in BDNF expression have been associated with depression and dementia.53 The association of increased BDNF expression with worse cognitive performance in our patients is thus unlikely causal, albeit BDNF can also modify glutamate signaling directly, by changing the expression of glutamate receptor subunits and Ca2+-regulating proteins in neurons, and directly activate post-synaptic NMDA receptors and could thus further offset the interplay between neurotransmitters in the vicinity of gliomas.