BDNF and Parkinson disease: Treatment with neurotrophins, especially with BDNF, has been extensively researched in neurodegenerative diseases such as Alzheimer, Parkinson and Huntington diseases.111 Decreased levels of BDNF were found in the brains of these patients and treatment with BNDF rescued neurons from cell death in animal studies.111,112 In this review, adjunctive treatment with neurotrophins might be protective against hearing loss, as treatment with BDNF and neurotrophin-3 reduced hearing impairment in one study each.