There may be no significant increase of cerebrospinal fluid tyrosine levels in patients with Parkinson's Disease.

With great interest, we read the article by Jimenez-Jimenez et al. entitled "Cerebrospinal and blood levels of amino acids as potential biomarkers for Parkinson's Disease: review and meta-analysis." published in the August 2020 issue of European Journal of Neurology1 . The study is of profound academic importance, and there are some points we would like to address.