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Parkinson disease (PD) is a progressive neurodegenerative disorder characterized by motor and non-motor symptoms and signs. Many reports suggest that diminished heart rate variability occurs early, even prior to the cardinal signs of PD. In a longitudinal study of PD, we evaluated whether heart rate variability (HRV) obtained using a 10-second ECG tracing, and the electrocardiographic QT-interval would be associated with PD severity and progression. Subjects were derived from a longitudinal study of 1741 individuals with early, stable PD. The severity of PD was measured using the global statistical test (GST). In a subset, the heart rate corrected QT-interval (QTcB) was calculated for each electrocardiogram (ECG). The HRV was measured for each ECG and then transformed to fit a normal distribution. The baseline analysis included 653 subjects, with 256 completing the 5-year follow up study. There was an association (P

BackgroundRecognizing the factors associated with falling in Parkinson's disease (PD) would improve identification of at-risk individuals.ObjectiveTo examine frequency of falling and baseline characteristics associated with falling in PD using the National Institute of Neurological Disorders and Stroke (NINDS) Exploratory Trials in PD Long-term Study-1 (NET-PD LS-1) dataset.MethodsThe LS-1 database included 1741 early treated PD subjects (median 4year follow-up). Baseline characteristics were tested for a univariate association with post-baseline falling during the trial. Significant variables were included in a multivariable logistic regression model. A separate analysis using a negative binomial model investigated baseline factors on fall rate.Results728 subjects (42%) fell during the trial, including at baseline. A baseline history of falls was the factor most associated with post-baseline falling. Men had lower odds of post-baseline falling compared to women, but for men, the probability of a post-baseline fall increased with age such that after age 70, men and women had similar odds of falling. Other baseline factors associated with a post-baseline fall and increased fall rate included the Unified PD Rating Scale (UPDRS) Activities of Daily Living (ADL) score, total functional capacity (TFC), baseline ambulatory capacity score and dopamine agonist monotherapy.ConclusionFalls are common in early treated PD. The biggest risk factor for falls in PD remains a history of falling. Measures of functional ability (UPDRS ADL, TFC) and ambulatory capacity are novel clinical risk factors needing further study. A significant age by sex interaction may help to explain why age has been an inconsistent risk factor for falls in PD.

Caffeine is neuroprotective in animal models of Parkinson's disease (PD) and caffeine intake is inversely associated with the risk of PD. This association may be influenced by the genotype of GRIN2A, which encodes an NMDA-glutamate-receptor subunit. In two placebo-controlled studies, we detected no association of caffeine intake with the rate of clinical progression of PD, except among subjects taking creatine, for whom higher caffeine intake was associated with more rapid progression. We now have analyzed data from 420 subjects for whom DNA samples and caffeine intake data were available from a placebo-controlled study of creatine in PD. The GRIN2A genotype was not associated with the rate of clinical progression of PD in the placebo group. However, there was a 4-way interaction between GRIN2A genotype, caffeine, creatine and the time since baseline. Among subjects in the creatine group with high levels of caffeine intake, but not among those with low caffeine intake, the GRIN2A T allele was associated with more rapid progression (p=0.03). These data indicate that the deleterious interaction between caffeine and creatine with respect to rate of progression of PD is influenced by GRIN2A genotype. This example of a genetic factor interacting with environmental factors illustrates the complexity of gene-environment interactions in the progression of PD.

ObjectiveIncreased caffeine intake is associated with a lower risk of Parkinson disease (PD) and is neuroprotective in mouse models of PD. However, in a previous study, an exploratory analysis suggested that, in patients taking creatine, caffeine intake was associated with a faster rate of progression. In the current study, we investigated the association of caffeine with the rate of progression of PD and the interaction of this association with creatine intake.MethodsData were analyzed from a large phase 3 placebo-controlled clinical study of creatine as a potentially disease-modifying agent in PD. Subjects were recruited for this study from 45 movement disorders centers across the United States and Canada. A total of 1741 subjects with PD participated in the primary clinical study, and caffeine intake data were available for 1549 of these subjects. The association of caffeine intake with rate of progression of PD as measured by the change in the total Unified Parkinson Disease Rating Scale score and the interaction of this association with creatine intake were assessed.ResultsCaffeine intake was not associated with the rate of progression of PD in the main analysis, but higher caffeine intake was associated with significantly faster progression among subjects taking creatine.ConclusionsThis is the largest and longest study conducted to date that addresses the association of caffeine with the rate of progression of PD. These data indicate a potentially deleterious interaction between caffeine and creatine with respect to the rate of progression of PD.

BackgroundThe effects of dopaminergic therapy in parkinson's disease (PD) can vary depending on the class of medication selected.ObjectiveThe aim of this post hoc study was to determine if the class of dopaminergic therapy correlated with disease severity in persons with early, treated PD.MethodsA non-parametric global statistical test (GST) was used to assess the status of participants treated with dopamine agonist (DA) monotherapy, levodopa (LD) monotherapy or combined LD and DA therapy on multiple PD outcomes encompassing motor, cognitive, psychiatric and autonomic function, as well as disability and quality of life.ResultsThe outcomes measured at the beginning of the study showed lower disease burden for participants on initial DA monotherapy compared to those taking combined LD and DA therapy after controlling for age, education, taking cog-meds and amantadine.ConclusionThis observation suggests that clinicians treating early PD patients favor combined LD and DA therapy in patients with more disabling features over DA monotherapy. As such, studies of PD progression in treated PD patients may be affected by the class of symptomatic dopaminergic therapy.

ImportanceThere are no treatments available to slow or prevent the progression of Parkinson disease, despite its global prevalence and significant health care burden. The National Institute of Neurological Disorders and Stroke Exploratory Trials in Parkinson Disease program was established to promote discovery of potential therapies.ObjectiveTo determine whether creatine monohydrate was more effective than placebo in slowing long-term clinical decline in participants with Parkinson disease.Design, setting, and patientsThe Long-term Study 1, a multicenter, double-blind, parallel-group, placebo-controlled, 1:1 randomized efficacy trial. Participants were recruited from 45 investigative sites in the United States and Canada and included 1741 men and women with early (within 5 years of diagnosis) and treated (receiving dopaminergic therapy) Parkinson disease. Participants were enrolled from March 2007 to May 2010 and followed up until September 2013.InterventionsParticipants were randomized to placebo or creatine (10 g/d) monohydrate for a minimum of 5 years (maximum follow-up, 8 years).Main outcomes and measuresThe primary outcome measure was a difference in clinical decline from baseline to 5-year follow-up, compared between the 2 treatment groups using a global statistical test. Clinical status was defined by 5 outcome measures: Modified Rankin Scale, Symbol Digit Modalities Test, PDQ-39 Summary Index, Schwab and England Activities of Daily Living scale, and ambulatory capacity. All outcomes were coded such that higher scores indicated worse outcomes and were analyzed by a global statistical test. Higher summed ranks (range, 5-4775) indicate worse outcomes.ResultsThe trial was terminated early for futility based on results of a planned interim analysis of participants enrolled at least 5 years prior to the date of the analysis (n = 955). The median follow-up time was 4 years. Of the 955 participants, the mean of the summed ranks for placebo was 2360 (95% CI, 2249-2470) and for creatine was 2414 (95% CI, 2304-2524). The global statistical test yielded t1865.8 = -0.75 (2-sided P = .45). There were no detectable differences (P

Progress in neurodegenerative disease research is hampered by the lack of biomarkers of neuronal dysfunction. We here identified a class of cerebrospinal fluid-based (CSF-based) kinetic biomarkers that reflect altered neuronal transport of protein cargo, a common feature of neurodegeneration. After a pulse administration of heavy water (2H2O), distinct, newly synthesized 2H-labeled neuronal proteins were transported to nerve terminals and secreted, and then appeared in CSF. In 3 mouse models of neurodegeneration, distinct 2H-cargo proteins displayed delayed appearance and disappearance kinetics in the CSF, suggestive of aberrant transport kinetics. Microtubule-modulating pharmacotherapy normalized CSF-based kinetics of affected 2H-cargo proteins and ameliorated neurodegenerative symptoms in mice. After 2H2O labeling, similar neuronal transport deficits were observed in CSF of patients with Parkinson's disease (PD) compared with non-PD control subjects, which indicates that these biomarkers are translatable and relevant to human disease. Measurement of transport kinetics may provide a sensitive method to monitor progression of neurodegeneration and treatment effects.