Longitudinal analyses of cerebrospinal fluid α-Synuclein in prodromal and early Parkinson's disease.

BACKGROUND: Aggregation of α-synuclein is central to the pathophysiology of PD. Biomarkers related to α-synuclein may be informative for PD diagnosis/progression. OBJECTIVES: To analyze α-synuclein in CSF in drug-naïve PD, healthy controls, and prodromal PD in the Parkinson's Progression Markers Initiative. METHODS: Over up to 36-month follow-up, CSF total α-synuclein and its association with MDS-UPDRS motor scores, cognitive assessments, and dopamine transporter imaging were assessed. RESULTS: The inception cohort included PD (n = 376; age [mean {standard deviation} years]: 61.7 [9.62]), healthy controls (n = 173; age, 60.9 [11.3]), hyposmics (n = 16; age, 68.3 [6.15]), and idiopathic rapid eye movement sleep behavior disorder (n = 32; age, 69.3 [4.83]). Baseline CSF α-synuclein was lower in manifest and prodromal PD versus healthy controls. Longitudinal α-synuclein decreased significantly in PD at 24 and 36 months, did not change in prodromal PD over 12 months, and trended toward an increase in healthy controls. The decrease in PD was not shown when CSF samples with high hemoglobin concentration were removed from the analysis. CSF α-synuclein changes did not correlate with longitudinal MDS-UPDRS motor scores or dopamine transporter scan. CONCLUSIONS: CSF α-synuclein decreases early in the disease, preceding motor PD. CSF α-synuclein does not correlate with progression and therefore does not reflect ongoing dopaminergic neurodegeneration. Decreased CSF α-synuclein may be an indirect index of changes in the balance between α-synuclein secretion, solubility, or aggregation in the brain, reflecting its overall turnover. Additional biomarkers more directly related to α-synuclein pathophysiology and disease progression and other markers to be identified by, for example, proteomics and metabolomics are needed. © 2019 International Parkinson and Movement Disorder Society.

Lack of independent mood-enhancing effect for dopaminergic medications in early Parkinson's disease.

BACKGROUND: A direct antidepressant effect has been reported for certain dopaminergic medications used in the treatment of Parkinson's disease (PD). OBJECTIVE: To examine whether dopaminergic medications may exert differential effects on mood in early PD. METHODS: We analyzed prospectively-collected 5-year data on 405 early, drug-naïve (at baseline) PD patients enrolled in the Parkinson's Progression Markers Initiative (PPMI) cohort study, initiated on levodopa, dopamine agonists (DAs), or monoamine-oxidase type B inhibitors (iMAO-B) under naturalistic conditions. The outcome for depressive symptoms was the 15-item Geriatric Depression Scale (GDS-15) score. Potential motor and cognitive confounders were measured using the Unified Parkinson's disease Rating Scale (MDS-UPDRS-III) and the Montreal Cognitive Assessment (MoCA). Three statistical models were used to determine medication effects on GDS-15 scores: unadjusted, adjusted, and a marginal structural model. RESULTS: One-third of patients in this cohort met GDS-15 threshold for clinically-significant depressive symptoms (GDS-15 ≥ 5). There was a marginal positive effect on GDS-15 scores after iMAO-B treatment initiation (-0.35 95%; CI: -0.73, 0.04; p = 0.08). There were no significant interactions between any of the three medication groups, but robust interactions between MoCA scores and both DAs (p = 0.005) and iMAO-B (p = 0.03) use on GDS-15 scores. Specifically, as MoCA scores worsened, DAs yielded a steeper worsening of GDS-15 scores while iMAO-B a moderating effect on GDS-15. CONCLUSION: Dopaminergic medications have no direct effect on mood in early, unselected PD patients.

Self-reported physical activity levels and clinical progression in early Parkinson's disease.

INTRODUCTION: This study investigates longitudinal changes in self-reported physical activity, measured by Physical Activity Scale of the Elderly (PASE), in early Parkinson's disease (PD) and matched healthy control (HC) participants in the Parkinson's Progression Marker Initiative (PPMI) and evaluates associations between physical activity and PD progression. METHODS: PPMI is a prospective, longitudinal study evaluating markers of progression in PD participants who are unmedicated at enrollment. PASE, a self-reported measure of physical activity, was administered to early PD (N = 380) and HC (N = 174). PASE was introduced after study launch and therefore administered at years 2, 3, and 4. PASE scores for PD and HC were compared with t-tests and changes over time were evaluated with generalized estimating equations. RESULTS: There were no differences in activity levels between PD and HC at any time point. However, PD participants had a longitudinal decrease in PASE from years two to four (p = 0.034), while HC did not (p = 0.89). In exploratory analyses controlling for age, sex, and disease duration, higher self-reported activity at year 2 were associated with slower progression of motor symptoms (p = 0.018), ADL performance (p < 0.0001), depression (p = 0.001), anxiety (p = 0.002), and cognitive decline (p = 0.016) over two years. These findings remained significant after adjusting for disease severity. CONCLUSION: There are no differences in self-reported physical activity between HC and early PD, but activity levels decline longitudinally in PD. Exploratory analyses show that higher self-reported physical activity is associated with less disease progression. Therefore, interventions to increase physical activity in early PD could potentially modify the disease course.

Longitudinal CSF biomarkers in patients with early Parkinson disease and healthy controls.

OBJECTIVE: To analyze longitudinal levels of CSF biomarkers in drug-naive patients with Parkinson disease (PD) and healthy controls (HC), examine the extent to which these biomarker changes relate to clinical measures of PD, and identify what may influence them. METHODS: CSF α-synuclein (α-syn), total and phosphorylated tau (t- and p-tau), and ß-amyloid 1-42 (Aß42) were measured at baseline and 6 and 12 months in 173 patients with PD and 112 matched HC in the international multicenter Parkinson's Progression Marker Initiative. Baseline clinical and demographic variables, PD medications, neuroimaging, and genetic variables were evaluated as potential predictors of CSF biomarker changes. RESULTS: CSF biomarkers were stable over 6 and 12 months, and there was a small but significant increase in CSF Aß42 in both patients with patients with PD and HC from baseline to 12 months. The t-tau remained stable. The p-tau increased marginally more in patients with PD than in HC. α-syn remained relatively stable in patients with PD and HC. Ratios of p-tau/t-tau increased, while t-tau/Aß42 decreased over 12 months in patients with PD. CSF biomarker changes did not correlate with changes in Movement Disorder Society-sponsored revision of the Unified Parkinson's Disease Rating Scale motor scores or dopamine imaging. CSF α-syn levels at 12 months were lower in patients with PD treated with dopamine replacement therapy, especially dopamine agonists. CONCLUSIONS: These core CSF biomarkers remained stable over 6 and 12 months in patients with early PD and HC. PD medication use may influence CSF α-syn. Novel biomarkers are needed to better profile progressive neurodegeneration in PD.