It is speculated that (R)-ketamine may play a neuroprotective role in counteracting MPTP-induced neurotoxic effects in the PD brain by activating the BDNF-TrkB signaling pathway in the striatum and SNr (Fujita et al., 2020), suggesting that it may be a possible new drug in the future for the prevention or treatment of neurodegenerative diseases such as Parkinson’s disease. Here, BDNF is linked to Parkinson disease.