Dietary Antioxidants and Risk of Parkinson's Disease in the Singapore Chinese Health Study.

BACKGROUND: Despite experimental evidence implicating oxidative stress in the pathogenesis of PD, epidemiological studies have provided inconsistent associations between dietary antioxidants and risk of developing PD. Furthermore, no study has been done in any Asian population. OBJECTIVES: We examined the associations for intake levels of dietary carotenoids (α-carotene, ß-carotene, lycopene, ß-cryptoxanthin, and lutein) and vitamins (vitamin A, C and E) and the risk of developing PD. METHODS: We used data from the Singapore Chinese Health Study, a population-based prospective cohort of 63,257 men and women aged 45 to 74 years during enrollment in 1993-1998. Antioxidant intake was derived from a validated semiquantitative food frequency questionnaire. Incident cases were identified through follow-up interviews, hospital records, or PD registries through 31 July 2018. Hazard ratios and corresponding 95% confidence intervals were derived from multivariable Cox proportional hazard regression models with adjustment for other lifestyle and dietary factors. RESULTS: During an average 19.4 years of follow-up, 544 incident PD cases were identified. No association was found for dietary carotenoids, individually or summed. Hazard ratio comparing highest to lowest quartile for total carotenoids was 0.98 (95% confidence interval: 0.76-1.28; Ptrend = 0.83). There were also no clear dose-dependent associations of dietary vitamins A, C, and E with risk of developing PD (all Ptrend ≥ 0.10). Sensitive analyses with lag time and excluding supplement use did not materially alter results. CONCLUSIONS: Intake of dietary antioxidants, such as carotenoids and vitamins, was not associated with the risk of developing PD in Singaporean Chinese. © 2020 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Stability of MDS-UPDRS Motor Subtypes Over Three Years in Early Parkinson's Disease.

Background: Various classifications have been proposed to subtype Parkinson's disease (PD) based on their motor phenotypes. However, the stability of these subtypes has not been properly evaluated. Objective: The goal of this study was to understand the distribution of PD motor subtypes, their stability over time, and baseline factors that predicted subtype stability. Methods: Participants (n = 170) from two prospective cohorts were included: the Early PD Longitudinal Singapore (PALS) study and the National Neuroscience Institute Movement Disorders Database. Early PD patients were classified into tremor-dominant (TD), postural instability and gait difficulty (PIGD), and indeterminate subtypes according to the Movement Disorder Society's Unified PD Rating Scale (MDS-UPDRS) criteria and clinically evaluated for three consecutive years. Results: At baseline, 60.6% patients were TD, 12.4% patients were indeterminate, and 27.1% patients were PIGD subtypes (p < 0.05). After 3 years, only 62% of patients in TD and 50% of patients in PIGD subtypes remained stable. The mean levodopa equivalent daily dose (LEDD) was higher in the PIGD subtype (276.92 ± 232.91 mg; p = 0.01). Lower LEDD [p < 0.05, odds ratio (OR) 0.99, 95% confidence interval (CI): 0.98-0.99] and higher TD/PIGD ratios (p < 0.05, OR 1.77, 95% CI: 1.29-2.43) were independent predictors of stability of TD subtype with an area under the curve (AUC) of 0.787 (95%CI: 0.669-0.876), sensitivity = 57.8%, and specificity = 89.7%. Conclusion: Only 50-62% of PD motor subtypes as defined by MDS-UPDRS remained stable over 3 years. TD/PIGD ratio and baseline LEDD were independent predictors for TD subtype stability over 3 years.