Several recent studies also indicated a potential role of KP dysregulation in Parkinson’s Disease (PD) progression, and in this light, Wilson et al. (2025, pre-print), showed that increased neuroexcitatory as defined by the QA/KA ratio in both plasma and CSF of 177 PD participants was associated with both peripheral and cerebral inflammation as well as vitamin B6 deficiency [37]. Here, NPPA is linked to Parkinson disease.