In this way, early loss of neurotrophic support in neurodegenerative diseases, especially BDNF signaling, often feeds into a vicious cycle of molecular events: reduced BDNF signaling impedes the neuronal ability to maintain functional transport systems and synaptic connections, which in turn decreases both the release of BDNF and the response to its presence through its receptors. This evidence concerns the gene BDNF and neurodegenerative disease.