Reduced cerebrospinal fluid taurine is associated with nigrostriatal dopaminergic deficits in drug-naïve Parkinson's disease.

The relationship between plasma or cerebrospinal fluid (CSF) amino acid levels and the pathophysiology of Parkinson's disease (PD) remains unclear. We aimed to examine the association of plasma and CSF amino acid levels with the nigrostriatal dopaminergic neurons and the clinical symptoms of newly diagnosed drug-naïve patients with PD. This was a cross-sectional study using the Jikei University PD registry. A total of 45 amino acids were measured in both plasma and CSF, and their associations with key clinical parameters were investigated. Multiple linear regression analyses were conducted to evaluate whether amino acids served as major explanatory variables for clinical parameters in PD. Forty-five drug-naïve patients were enrolled. The mean age was 68.6 ± 9.6, and disease duration was 2.5 years (± 2.1). MDS-UPDRS Part III score averaged 28.1 (± 13.3). Among the measured plasma and CSF amino acids, only CSF taurine levels were identified as independent factors for SBR, MDS-UPDRS Part II, and Part III scores in multivariate analysis (β = 0.39 [95% CI 0.13 to 0.65, p = 0.005], -0.46 [95% CI -0.76 to -0.15, p = 0.004], -0.39 [95% CI -0.73 to -0.05, p = 0.02], respectively). Higher CSF taurine levels were associated with more preserved SBR on