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Essential tremor is the most common movement disorder with clear unmet need. Mounting evidence indicates tremor is caused by increased neuronal burst firing and oscillations in cerebello-thalamo-cortical circuitry and may be dependent on T-type calcium channel activity. T-type calcium channels regulate sigma band electroencephalogram (EEG) power during non-rapid eye movement sleep, representing a potential biomarker of channel activity. PRAX-944 is a novel T-type calcium channel blocker in development for essential tremor.Using a rat tremor model and sigma-band EEG power, we assessed pharmacodynamically-active doses of PRAX-944 and their translation into clinically tolerated doses in healthy participants, informing dose selection for future efficacy trials.Harmaline-induced tremor and spontaneous locomotor activity were used to assess PRAX-944 efficacy and tolerability, respectively, in rats. Sigma-power was used as a translational biomarker of T-type calcium channel blockade in rats and, subsequently, in a phase 1 trial assessing pharmacologic activity and tolerability in healthy participants.In rats, PRAX-944 dose-dependently reduced tremor by 50% and 72% at 1 and 3 mg/kg doses, respectively, without locomotor side effects. These doses also reduced sigma-power by ~30% to 50% in rats. In healthy participants, sigma-power was similarly reduced by 34% to 50% at 10 to 100 mg, with no further reduction at 120 mg. All doses were well tolerated.In rats, PRAX-944 reduced sigma-power at concentrations that reduced tremor without locomotor side effects. In healthy participants, comparable reductions in sigma-power indicate that robust T-type calcium channel blockade was achieved at well-tolerated doses that may hold promise for reducing tremor in patients with essential tremor. © 2022 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Essential tremor (ET) affects approximately 7 million people in the USA, yet public recognition of the disease and its impact remain low.A retrospective observational study examined US claims data from 2015 to 2019 using the Compile database. ET diagnoses were captured using longitudinal data from 2015 to 2019 and for the year 2019, with diagnosis estimates extrapolated to the general US population. Confirmed ET was identified by an ET diagnosis code with at least two relevant prescriptions or by two diagnosis codes for ET and unspecified tremor at least 90 days apart. Comorbidity and treatment use data were extracted, and medication compliance and 2-year treatment persistence were assessed as measures of treatment adherence.A total of 1,336,183 patients with ET diagnoses codes were identified from 2015 through 2019, corresponding to 2,226,971 projected US diagnoses. In 2019, 128,263 patients had a confirmed ET diagnosis, corresponding to 213,772 projected US confirmed diagnoses. Of these, 96% had at least one comorbidity, and 64% received at least one pharmacologic treatment. Propranolol (24%) and primidone (20%) comprised the most common ET prescriptions. Two-year medication discontinuation rates were approximately 40%.Our findings revealed that 1 million people were diagnosed and sought treatment for ET in the USA from 2015 to 2019. Projected population estimates of approximately 2 million people diagnosed suggest a further 1 million remain untreated. Our findings highlight the complexity of patient care in ET, complicated by delayed diagnoses, multiple comorbidities, and lack of effective and tolerable therapies that can mitigate treatment adherence limitations.

The Parkinson Associated Risk Syndrome (PARS) study was designed to evaluate whether screening with olfactory testing and dopamine transporter (DAT) imaging could identify participants at risk for developing Parkinson's disease (PD).Hyposmia on a single test has been associated with increased risk of PD, but, taken alone, lacks specificity. We evaluated whether repeating olfactory testing improves the diagnostic characteristics of this screening approach.Participants completed up to 10 years of clinical and imaging evaluations in the PARS cohort. Olfaction was assessed with the University of Pennsylvania Smell Identification Test at baseline and on average 1.4 years later. Multiple logistic regression and Cox proportional hazards regression were used to estimate the hazard of development of clinical PD or abnormal DAT imaging.Of 186 participants who were initially hyposmic, 28% reverted to normosmia on repeat testing (reverters). No initially normosmic subjects and only 2% of reverters developed DAT imaging progression or clinical PD, compared to 29% of subjects with persistent hyposmia who developed abnormal DAT and 20% who developed clinical PD. The relative risk of clinical conversion to PD was 8.3 (95% CI:0.92-75.2, p = 0.06) and of abnormal DAT scan was 12.5 (2.4-156.2, p = 0.005) for persistent hyposmia, compared to reversion.Persistent hyposmia on serial olfactory testing significantly increases the risk of developing clinical PD and abnormal DAT imaging, compared to hyposmia on a single test. Repeat olfactory testing may be an efficient and cost-effective strategy to improve identification of at-risk patients for early diagnosis and disease modification studies.

ObjectiveTo quantify the percent volume of dilated perivascular spaces (PVS) in the subcortical forebrain in patients with early Huntington's disease (HD) and to explore the relationship between PVS and disease severity.MethodsMRI scans were performed on 25 HD patients and 23 healthy age-matched controls at Massachusetts General Hospital. The imaging data were analyzed using a novel algorithm to determine regional PVS volume. A fractional logistic regression analysis was used to quantify the association between regional percent PVS volume and (1) disease designation (HD or Control) and (2) disease severity as assessed by normalized caudate volume.ResultsHD patients had the greatest percent volume of dilated PVS in the putamen (left putamen: odds ratio 2.06 [95% CI: 1.62–2.62], HD 3.27% [95% CI: 2.83–3.78] vs Controls 1.62% [1.32–1.97], pfdr < 0.001; right putamen odds ratio 1.66 [95% CI: 1.33–2.08], HD 3.43% [95% CI: 2.94–4.01] vs Controls 2.09% [95% CI: 1.79–2.45] pfdr < 0.001) and several subcortical white matter regions, as compared to controls. Dilated PVS increased with disease severity.ConclusionsThe objective quantification of dilated PVS suggests that PVS burden is high, associated with disease severity and may impact the distribution and success of treatments administered either intrathecally, such as antisense oligonucleotides (ASOs) or by intraparenchymal administration, such as cell and gene therapies. Classification of Evidence Review: This study provides Class II evidence that increased dilated PVS is associated with worse Huntington's disease severity. The study is rated Class II because of the cross-sectional design.

Loss of nigrostriatal dopaminergic projection neurons is a key pathology in Parkinson’s disease, leading to abnormal function of basal ganglia motor circuits and the accompanying characteristic motor features. A number of intraparenchymally delivered gene therapies designed to modify underlying disease and/or improve clinical symptoms have shown promise in preclinical studies and subsequently were evaluated in clinical trials. Here we review the challenges with surgical delivery of gene therapy vectors that limited therapeutic outcomes in these trials, particularly the lack of real-time monitoring of vector administration. These challenges have recently been addressed during the evolution of novel techniques for vector delivery that include the use of intraoperative MRI. The preclinical development of these techniques are described in relation to recent clinical translation in an adeno-associated virus serotype 2-mediated human aromatic L-amino acid decarboxylase gene therapy development programme. This new paradigm allows visualisation of the accuracy and adequacy of viral vector delivery within target structures, enabling intertrial modifications in surgical approaches, cannula design, vector volumes and dosing. The rapid, data-driven evolution of these procedures is unique and has led to improved vector delivery.

BACKGROUND AND OBJECTIVES The PARS (Parkinson Associated Risk Syndrome) study was designed to test whether screening for hyposmia followed by dopamine transporter imaging can identify risk for conversion to clinical PD, and to evaluate progression markers during the prodromal period. METHODS Subjects with hyposmia completed annual clinical evaluations and biennial [123 I]s-CIT single-photon emission computed tomography scans. Subjects were categorized as normal (>80% age-expected tracer uptake; n = 134), indeterminate (>65-80%; n = 30), and dopamine transporter deficit (≤65%; n = 21) by their baseline scan, and survival analysis was used to compare risk of conversion to motor PD. Progressing to a scan with a dopamine transporter deficit was assessed for those subjects with either normal or indeterminate baseline imaging. RESULTS Over a mean of 6.3 [standard deviation: 2.2] years of follow-up, 67% (n = 14) of dopamine transporter deficit subjects, 20% (n = 6) of dopamine transporter indeterminate subjects, and 4% (n = 6) of dopamine transporter normal subjects converted to a PD diagnosis (P

Author(s): Nutt, John G; Curtze, Carolin; Hiller, Amie; Anderson, Shannon; Larson, Paul S; Van Laar, Amber D; Richardson, R Mark; Thompson, Marin E; Sedkov, Alexander; Leinonen, Mika; Ravina, Bernard; Bankiewicz, Krystof S; Christine, Chadwick W | Abstract: BackgroundAs Parkinson's disease progresses, levodopa treatment loses efficacy, partly through the loss of the endogenous dopamine-synthesizing enzyme L-amino acid decarboxylase (AADC). In the phase I PD-1101 study, putaminal administration of VY-AADC01, an investigational adeno-associated virus serotype-2 vector for delivery of the AADC gene in patients with advanced Parkinson's disease, was well tolerated, improved motor function, and reduced antiparkinsonian medication requirements.ObjectivesThis substudy aimed to determine whether the timing and magnitude of motor response to intravenous levodopa changed in PD-1101 patients after VY-AADC01 administration.MethodsParticipants received 2-hour threshold (0.6 mg/kg/h) and suprathreshold (1.2 mg/kg/h) levodopa infusions on each of 2 days, both before and approximately 6 months after VY-AADC01. Infusion order was randomized and double blinded. Unified Parkinson's Disease Rating Scale motor scores, finger-tapping speeds, and dyskinesia rating scores were assessed every 30 minutes for 1 hour before and ≥3 hours after start of levodopa infusion.ResultsOf 15 PD-1101 patients, 13 participated in the substudy. Unified Parkinson's Disease Rating Scale motor score area under the curve responses to threshold and suprathreshold levodopa infusions increased by 168% and 67%, respectively, after VY-AADC01; finger-tapping speeds improved by 162% and 113%, and dyskinesia scores increased by 208% and 72%, respectively, after VY-AADC01. Adverse events (mild/moderate severity) were reported in 5 participants during levodopa infusions pre-VY-AADC01 and 2 participants post-VY-AADC01 administration.ConclusionsVY-AADC01 improved motor responses to intravenous levodopa given under controlled conditions. These data and findings from the parent study support further clinical development of AADC gene therapy for people with Parkinson's disease. © 2020 The Authors. Movement Disorders published by Wiley Periodicals, Inc. on behalf of International Parkinson and Movement Disorder Society.

Objective Experimental therapies under development for Friedreich’s Ataxia (FRDA) require validated biomarkers. In‐vivo reflectance confocal microscopy (RCM) of skin is a noninvasive way to quantify Meissner’s corpuscle (MC) density and has emerged as a sensitive measure of sensory polyneuropathies. We conducted a prospective, cross‐sectional study evaluating RCM of MCs and conventional peripheral nerve measures as candidate peripheral nerve markers in FRDA. Methods Sixteen individuals with FRDA and 16 age‐ and gender‐matched controls underwent RCM of MC density and morphology, skin biopsies for epidermal nerve fiber density (ENFD), nerve conduction studies (NCS), and quantitative sensory testing (QST) including touch, vibration, and cooling thresholds. Results MC densities were measurable in all participants with FRDA, and were lower at digit V (hand), thenar eminence, and arch (foot) compared to controls. By contrast, sensory NCS showed floor effects and were obtainable in only 13% of FRDA participants. QST thresholds for touch, vibration, and cooling were higher at the hand and foot in FRDA than controls. Reductions in ENFDs were present in more severely affected individuals with FRDA (Friedreich’s Ataxia Rating Scale (FARS) >60) compared to matched controls, although skin biopsies were not well tolerated in children. MC densities, ENFDs, and touch and vibration thresholds were associated with clinical disease severity (FARS and modified FARS) and duration since symptom onset. Interpretation MC density, ENFD, and QST thresholds provide structural and physiologic markers of sensory involvement in FRDA. Longitudinal evaluation is needed to determine whether these measures can identify changes associated with disease progression or treatment.

A key driver of patients' well-being and clinical trials for Parkinson's disease (PD) is the course that the disease takes over time (progression and prognosis). To assess how genetic variation influences the progression of PD over time to dementia, a major determinant for quality of life, we performed a longitudinal genome-wide survival study of 11.2 million variants in 3,821 patients with PD over 31,053 visits. We discover RIMS2 as a progression locus and confirm this in a replicate population (hazard ratio (HR) = 4.77, P = 2.78 x 10(-11)), identify suggestive evidence for TMEM108 (HR = 2.86, P = 2.09 x 10(-8)) and WWOX (HR = 2.12, P = 2.37 x 10(-8)) as progression loci, and confirm associations for GBA (HR = 1.93, P = 0.0002) and APOE (HR = 1.48, P = 0.001). Polygenic progression scores exhibit a substantial aggregate association with dementia risk, while polygenic susceptibility scores are not predictive. This study identifies a novel synaptic locus and polygenic score for cognitive disease progression in PD and proposes diverging genetic architectures of progression and susceptibility.A genome-wide survival study identifies variants at RIMS2 associated with progression of Parkinson's disease to dementia and highlights divergence in the genetic architecture of disease onset and progression.

Item does not contain fulltext BACKGROUND: Several reports have identified different patterns of Parkinson's disease progression in individuals carrying missense variants in GBA or LRRK2 genes. The overall contribution of genetic factors to the severity and progression of Parkinson's disease, however, has not been well studied. OBJECTIVES: To test the association between genetic variants and the clinical features of Parkinson's disease on a genomewide scale. METHODS: We accumulated individual data from 12 longitudinal cohorts in a total of 4093 patients with 22,307 observations for a median of 3.81 years. Genomewide associations were evaluated for 25 cross-sectional and longitudinal phenotypes. Specific variants of interest, including 90 recently identified disease-risk variants, were also investigated post hoc for candidate associations with these phenotypes. RESULTS: Two variants were genomewide significant. Rs382940(T>A), within the intron of SLC44A1, was associated with reaching Hoehn and Yahr stage 3 or higher faster (hazard ratio 2.04 [1.58-2.62]; P value = 3.46E-8). Rs61863020(G>A), an intergenic variant and expression quantitative trait loci for alpha-2A adrenergic receptor, was associated with a lower prevalence of insomnia at baseline (odds ratio 0.63 [0.52-0.75]; P value = 4.74E-8). In the targeted analysis, we found 9 associations between known Parkinson's risk variants and more severe motor/cognitive symptoms. Also, we replicated previous reports of GBA coding variants (rs2230288: p.E365K; rs75548401: p.T408M) being associated with greater motor and cognitive decline over time, and an APOE E4 tagging variant (rs429358) being associated with greater cognitive deficits in patients. CONCLUSIONS: We identified novel genetic factors associated with heterogeneity of Parkinson's disease. The results can be used for validation or hypothesis tests regarding Parkinson's disease. (c) 2019 International Parkinson and Movement Disorder Society.

Biomarkers have the potential to improve diagnosis and prognosis, and guide clinical treatment decisions. In research, biomarkers can be used for patient selection and as outcome measures in clinical trials. A range of biochemical and imaging biomarkers are relevant to patients with Lewy body disorders, including PD, PD dementia, and dementia with Lewy bodies. Dopaminergic imaging is used for differential diagnosis of parkinsonian disorders versus tremor disorders without dopamingeric deficits, and also to differentiate dementia with Lewy bodies from Alzheimer's disease. Markers of underlying Alzheimer's disease pathology have been applied to PD patients experiencing cognitive decline to determine the extent of mixed pathology in these cases. Assessment of alpha-synuclein species in spinal fluid is possible, and more specific assays attempt to identify alpha-synuclein aggregates or phosphorylated alpha-synuclein. While alpha-synuclein markers are intended to measure the pathology most central to PD dementia and dementia with Lewy bodies, convincing evidence of robust reliability and validity from multiple laboratories is lacking. Similarly, alpha-synuclein imaging by PET or single-photon emission computed tomography, while an important research goal, is not yet available. In addition to their uses in the clinic, biomarkers have natural uses in therapeutic trials that target cognitive and neuropsychiatric features of Lewy body disorders. The biomarkers most likely to be incorporated into trials are dopaminergic and amyloid imaging for the purpose of accurate patient selection, and possibly to demonstrate the utility of antiamyloid treatments in Lewy body disorders patients with mixed pathology. © 2018 International Parkinson and Movement Disorder Society.

Introduction In small trials, randomization can fail, leading to differences in patient characteristics across treatment arms, a risk that can be reduced by stratifying using key confounders. In ALS trials, riluzole use (RU) and bulbar onset (BO) have been used for stratification. We hypothesized that randomization could be improved by using a multifactorial prognostic score of predicted survival as a single stratifier. Methods We defined a randomization failure as a significant difference between treatment arms on a characteristic. We compared randomization failure rates when stratifying for RU and BO (“traditional stratification”) to failure rates when stratifying for predicted survival using a predictive algorithm. We simulated virtual trials using the PRO‐ACT database without application of a treatment effect to assess balance between cohorts. We performed 100 randomizations using each stratification method – traditional and algorithmic. We applied these stratification schemes to a randomization simulation with a treatment effect using survival as the endpoint and evaluated sample size and power. Results Stratification by predicted survival met with fewer failures than traditional stratification. Stratifying predicted survival into tertiles performed best. Stratification by predicted survival was validated with an external dataset, the placebo arm from the BENEFIT‐ALS trial. Importantly, we demonstrated a substantial decrease in sample size required to reach statistical power. Conclusions Stratifying randomization based on predicted survival using a machine learning algorithm is more likely to maintain balance between trial arms than traditional stratification methods. The methodology described here can translate to smaller, more efficient clinical trials for numerous neurological diseases.

Author(s): Christine, Chadwick W; Bankiewicz, Krystof S; Van Laar, Amber D; Richardson, R Mark; Ravina, Bernard; Kells, Adrian P; Boot, Brendon; Martin, Alastair J; Nutt, John; Thompson, Marin E; Larson, Paul S | Abstract: ObjectiveTo understand the safety, putaminal coverage, and enzyme expression of adeno-associated viral vector serotype-2 encoding the complementary DNA for the enzyme, aromatic L-amino acid decarboxylase (VY-AADC01), delivered using novel intraoperative monitoring to optimize delivery.MethodsFifteen subjects (three cohorts of 5) with moderately advanced Parkinson's disease and medically refractory motor fluctuations received VY-AADC01 bilaterally coadministered with gadoteridol to the putamen using intraoperative magnetic resonance imaging (MRI) guidance to visualize the anatomic spread of the infusate and calculate coverage. Cohort 1 received 8.3 × 1011 vg/ml and ≤450 μl per putamen (total dose, ≤7.5 × 1011 vg); cohort 2 received the same concentration (8.3 × 1011 vg/ml) and ≤900 μl per putamen (total dose, ≤1.5 × 1012 vg); and cohort 3 received 2.6 × 1012 vg/ml and ≤900 μl per putamen (total dose, ≤4.7 × 1012 vg). (18)F-fluoro-L-dihydroxyphenylalanine positron emission tomography (PET) at baseline and 6 months postprocedure assessed enzyme activity; standard assessments measured clinical outcomes.ResultsMRI-guided administration of ascending VY-AADC01 doses resulted in putaminal coverage of 21% (cohort 1), 34% (cohort 2), and 42% (cohort 3). Cohorts 1, 2, and 3 showed corresponding increases in enzyme activity assessed by PET of 13%, 56%, and 79%, and reductions in antiparkinsonian medication of -15%, -33%, and -42%, respectively, at 6 months. At 12 months, there were dose-related improvements in clinical outcomes, including increases in patient-reported ON-time without troublesome dyskinesia (1.6, 3.3, and 1.5 hours, respectively) and quality of life.InterpretationNovel intraoperative monitoring of administration facilitated targeted delivery of VY-AADC01 in this phase 1 study, which was well tolerated. Increases in enzyme expression and clinical improvements were dose dependent. ClinicalTrials.gov Identifier: NCT01973543 Ann Neurol 2019;85:704-714.

BackgroundSeveral reports have identified different patterns of Parkinson’s disease progression in individuals carrying missense variants in theGBAorLRRK2genes. The overall contribution of genetic factors to the severity and progression of Parkinson’s disease, however, has not been well studied.ObjectivesTo test the association between genetic variants and the clinical features and progression of Parkinson’s disease on a genome-wide scale.MethodsWe accumulated individual data from 12 longitudinal cohorts in a total of 4,093 patients with 25,254 observations over a median of 3.81 years. Genome-wide associations were evaluated for 25 cross-sectional and longitudinal phenotypes. Specific variants of interest, including 90 recently-identified disease risk variants, were also investigated for the associations with these phenotypes.ResultsTwo variants were genome-wide significant. Rs382940(T>A), within the intron ofSLC44A1, was associated with reaching Hoehn and Yahr stage 3 or higher faster (HR 2.04 [1.58, 2.62], P-value = 3.46E-8). Rs61863020(G>A), an intergenic variant and eQTL forADRA2A, was associated with a lower prevalence of insomnia at baseline (OR 0.63 [0,52, 0.75], P-value = 4.74E-8). In the targeted analysis, we found nine associations between known Parkinson’s risk variants and more severe motor/cognitive symptoms. Also, we replicated previous reports ofGBAcoding variants (rs2230288: p.E365K, rs75548401: p.T408M) being associated with greater motor and cognitive decline over time, andAPOEE4 tagging variant (rs429358) being associated with greater cognitive deficits in patients.ConclusionsWe identified novel genetic factors associated with heterogeneity of progression in Parkinson’s disease. The results provide new insights into the pathogenesis of Parkinson’s disease as well as patient stratification for clinical trials.

AIMS: BG00010 is a protein in the glial cell line-derived neurotrophic factor (GDNF) family. It is a selective ligand for the GDNF family receptor alpha-3 (GFRα3) co-receptor that normalizes cellular changes resulting from damage or disease, and potentially alleviates neuropathic pain. The main objectives of this study were to evaluate the pharmacokinetic and safety profiles and to determine the effects on pain of ascending doses of intravenous injections of BG00010 in patients with sciatica. METHODS: This was a randomized, blinded, placebo-controlled multiple-dose study in subjects with sciatica. In Part I (16 patients), four IV dose levels were examined (50, 150, 400, 800 μg kg(-1) ) and in Part II (12 patients), three dose levels were examined (400, 600 and 1200 μg kg(-1) ). Safety and efficacy assessments were used as endpoints. RESULTS: The BG00010 concentration-time data indicated relatively low inter-patient variability and there was a dose-dependent (not dose-proportional) increase in serum exposure from 150 to 1200 μg kg(-1) . The effective half-life was between 40 and 60 h. The most frequently occurring adverse events (AEs) reported by patients receiving BG00010 were headache (67-83%), feeling hot (50-100%), and pruritus (42-67%). Most AEs were mild; no serious AEs or AEs leading to discontinuation occurred. Higher dose regimens of BG00010 resulted in greater pain reduction than placebo or lower dose regimens, although a clear dose-response relationship was not seen. CONCLUSIONS: The pharmacokinetic profile of BG00010 was characterized by low intra-patient variability. These data from a small sample suggest that BG00010 may have a benefit for patients with sciatica. TRIAL REGISTRATION: ClinicalTrials.gov NCT00961766 NCT01405833 .

ObjectiveTo determine if any association between previously identified alleles that confer risk for Parkinson disease and variables measuring disease progression.MethodsWe evaluated the association between 31 risk variants and variables measuring disease progression. A total of 23,423 visits by 4,307 patients of European ancestry from 13 longitudinal cohorts in Europe, North America, and Australia were analyzed.ResultsWe confirmed the importance ofGBAon phenotypes.GBAvariants were associated with the development of daytime sleepiness (p.N370S: hazard ratio [HR] 3.28 [1.69–6.34]) and possible REM sleep behavior (p.T408M: odds ratio 6.48 [2.04–20.60]). We also replicated previously reported associations ofGBAvariants with motor/cognitive declines. The other genotype-phenotype associations include an intergenic variant nearLRRK2and the faster development of motor symptom (Hoehn and Yahr scale 3.0 HR 1.33 [1.16–1.52] for the C allele of rs76904798) and an intronic variant inPMVKand the development of wearing-off effects (HR 1.66 [1.19–2.31] for the C allele of rs114138760). Age at onset was associated withTMEM175variant p.M393T (−0.72 [−1.21 to −0.23] in years), the C allele of rs199347 (intronic region ofGPNMB, 0.70 [0.27–1.14]), and G allele of rs1106180 (intronic region ofCCDC62, 0.62 [0.21–1.03]).ConclusionsThis study provides evidence that alleles associated with Parkinson disease risk, in particularGBAvariants, also contribute to the heterogeneity of multiple motor and nonmotor aspects. Accounting for genetic variability will be a useful factor in understanding disease course and in minimizing heterogeneity in clinical trials.

Biomarkers have the potential to improve diagnosis and prognosis, and guide clinical treatment decisions. In research, biomarkers can be used for patient selection and as outcome measures in clinical trials. A range of biochemical and imaging biomarkers are relevant to patients with Lewy body disorders, including PD, PD dementia, and dementia with Lewy bodies. Dopaminergic imaging is used for differential diagnosis of parkinsonian disorders versus tremor disorders without dopamingeric deficits, and also to differentiate dementia with Lewy bodies from Alzheimer's disease. Markers of underlying Alzheimer's disease pathology have been applied to PD patients experiencing cognitive decline to determine the extent of mixed pathology in these cases. Assessment of alpha-synuclein species in spinal fluid is possible, and more specific assays attempt to identify alpha-synuclein aggregates or phosphorylated alpha-synuclein. While alpha-synuclein markers are intended to measure the pathology most central to PD dementia and dementia with Lewy bodies, convincing evidence of robust reliability and validity from multiple laboratories is lacking. Similarly, alpha-synuclein imaging by PET or single-photon emission computed tomography, while an important research goal, is not yet available. In addition to their uses in the clinic, biomarkers have natural uses in therapeutic trials that target cognitive and neuropsychiatric features of Lewy body disorders. The biomarkers most likely to be incorporated into trials are dopaminergic and amyloid imaging for the purpose of accurate patient selection, and possibly to demonstrate the utility of antiamyloid treatments in Lewy body disorders patients with mixed pathology. © 2018 International Parkinson and Movement Disorder Society.

Summary Background A systematic assessment of potential disease-modifying compounds for Parkinson's disease concluded that pioglitazone could hold promise for the treatment of patients with this disease. We assessed the effect of pioglitazone on the progression of Parkinson's disease in a multicentre, double-blind, placebo-controlled, futility clinical trial. Methods Participants with the diagnosis of early Parkinson's disease on a stable regimen of 1 mg/day rasagiline or 10 mg/day selegiline were randomly assigned (1:1:1) to 15 mg/day pioglitazone, 45 mg/day pioglitazone, or placebo. Investigators were masked to the treatment assignment. Only the statistical centre and the central pharmacy knew the treatment name associated with the randomisation number. The primary outcome was the change in the total Unified Parkinson's Disease Rating Scale (UPDRS) score between the baseline and 44 weeks, analysed by intention to treat. The primary null hypothesis for each dose group was that the mean change in UPDRS was 3 points less than the mean change in the placebo group. The alternative hypothesis (of futility) was that pioglitazone is not meaningfully different from placebo. We rejected the null if there was significant evidence of futility at the one-sided alpha level of 0·10. The study is registered at ClinicalTrials.gov , number NCT01280123 . Findings 210 patients from 35 sites in the USA were enrolled between May 10, 2011, and July 31, 2013. The primary analysis included 72 patients in the 15 mg group, 67 in the 45 mg group, and 71 in the placebo group. The mean total UPDRS change at 44 weeks was 4·42 (95% CI 2·55–6·28) for 15 mg pioglitazone, 5·13 (95% CI 3·17–7·08) for 45 mg pioglitazone, and 6·25 (95% CI 4·35–8·15) for placebo (higher change scores are worse). The mean difference between the 15 mg and placebo groups was −1·83 (80% CI −3·56 to −0·10) and the null hypothesis could not be rejected (p=0·19). The mean difference between the 45 mg and placebo groups was −1·12 (80% CI −2·93 to 0·69) and the null hypothesis was rejected in favour of futility (p=0·09). Planned sensitivity analyses of the primary outcome, using last value carried forward (LVCF) to handle missing data and using the completers' only sample, suggested that the 15 mg dose is also futile (p=0·09 for LVCF, p=0·09 for completers) but failed to reject the null hypothesis for the 45 mg dose (p=0·12 for LVCF, p=0·19 for completers). Six serious adverse events occurred in the 15 mg group, nine in the 45 mg group, and three in the placebo group; none were thought to be definitely or probably related to the study interventions. Interpretation These findings suggest that pioglitazone at the doses studied here is unlikely to modify progression in early Parkinson's disease. Further study of pioglitazone in a larger trial in patients with Parkinson's disease is not recommended. Funding National Institute of Neurological Disorders and Stroke.

There are no cures for neurodegenerative diseases and this is partially due to the difficulty of monitoring pathogenic molecules in patients during life. The Parkinson's disease gene α-synuclein (SNCA) is selectively expressed in blood cells and neurons. Here we show that SNCA transcripts in circulating blood cells are paradoxically reduced in early stage, untreated and dopamine transporter neuroimaging-supported Parkinson's disease in three independent regional, national, and international populations representing 500 cases and 363 controls and on three analogue and digital platforms with P < 0.0001 in meta-analysis. Individuals with SNCA transcripts in the lowest quartile of counts had an odds ratio for Parkinson's disease of 2.45 compared to individuals in the highest quartile. Disease-relevant transcript isoforms were low even near disease onset. Importantly, low SNCA transcript abundance predicted cognitive decline in patients with Parkinson's disease during up to 5 years of longitudinal follow-up. This study reveals a consistent association of reduced SNCA transcripts in accessible peripheral blood and early-stage Parkinson's disease in 863 participants and suggests a clinical role as potential predictor of cognitive decline. Moreover, the three independent biobank cohorts provide a generally useful platform for rapidly validating any biological marker of this common disease.

Background There are few established predictors of the clinical course of PD. Prognostic markers would be useful for clinical care and research. Objective To identify predictors of long-term motor and cognitive outcomes and rate of progression in PD. Methods Newly diagnosed PD participants were followed for 7 years in a prospective study, conducted at 55 centers in the United States and Canada. Analyses were conducted in 244 participants with complete demographic, clinical, genetic, and dopamine transporter imaging data. Machine learning dynamic Bayesian graphical models were used to identify and simulate predictors and outcomes. The outcomes rate of cognition changes are assessed by the Montreal Cognitive Assessment scores, and rate of motor changes are assessed by UPDRS part-III. Results The most robust and consistent longitudinal predictors of cognitive function included older age, baseline Unified Parkinson’s Disease Rating Scale (UPDRS) parts I and II, Schwab and England activities of daily living scale, striatal dopamine transporter binding, and SNP rs11724635 in the gene BST1. The most consistent predictor of UPDRS part III was baseline level of activities of daily living (part II). Key findings were replicated using long-term data from an independent cohort study. Conclusions Baseline function near the time of Parkinson’s disease diagnosis, as measured by activities of daily living, is a consistent predictor of long-term motor and cognitive outcomes. Additional predictors identified may further characterize the expected course of Parkinson’s disease and suggest mechanisms underlying disease progression. The prognostic model developed in this study can be used to simulate the effects of the prognostic variables on motor and cognitive outcomes, and can be replicated and refined with data from independent longitudinal studies.

Cognitive impairment in Parkinson's disease (PD) is common and does directly impact patients' everyday functioning. However, the underlying mechanisms of early cognitive decline are not known. This study explored the association between striatal dopaminergic deficits and cognitive impairment within a large cohort of early, drug-naive PD patients and tested the hypothesis that executive dysfunction in PD is associated with striatal dopaminergic depletion. A cross-sectional multicenter cohort of 339 PD patients and 158 healthy controls from the Parkinson's Progression Markers Initiative study was analyzed. Each individual underwent cerebral single-photon emission CT (SPECT) and a standardized neuropsychological assessment with tests of memory as well as visuospatial and executive function. SPECT imaging was performed with [123I]FP-CIT, and specific binding ratios in left and right putamen and caudate nucleus were calculated. The association between specific binding ratios, cognitive domain scores, and age was analyzed using Pearson's correlations, partial correlation, and conditional process analysis. A small, but significant, positive association between total striatal dopamine transporter binding and the attention/executive domain was found (r = 0.141; P = 0.009) in PD, but this was not significant after adjusting for age. However, in a moderated mediation model, we found that cognitive executive differences between controls and patients with PD were mediated by an age-moderated striatal dopaminergic deficit. Our findings support the hypothesis that nigrostriatal dopaminergic deficit is associated with executive impairment, but not to memory or visuospatial impairment, in early PD. © 2014 International Parkinson and Movement Disorder Society

Cognitive impairment and dementia associated with movement disorders represent a major management challenge and area of unmet need. This article has focused upon Parkinson’s disease as an exemplar condition, but many of the roadblocks and efforts to overcome these are applicable, in a general sense, to other disorders. Short of a “penicillin moment”—a chance discovery or piece of unintended good fortune—progress is likely to be incremental. Cognitive therapies may end up being multiple and possibly multimodal, parallel with the cancer therapy field. Ultimately, benefit for one condition may extend to others as commonality in protein aggregation, synergistic pathological effects between proteins, and pathological spread emerges.

The objective of this study was to examine a remote method for maintaining long-term contact with Parkinson's disease (PD) patients participating in clinical studies. Long-term follow-up of PD patients is needed to fill critical information gaps on progression, biomarkers, and treatment. Prospective in-person assessment can be costly and may be impossible for some patients. Remote assessment using mail and telephone contact may be a practical follow-up method. Patients enrolled in the multi-center Longitudinal and Biomarker Study in Parkinson's Disease (LABS-PD) in-person follow-up study in 2006 were invited to enroll in Follow-up of Persons With Neurologic Diseases (FOUND), which is overseen by a single center under a separate, central institutional review board protocol. FOUND uses mailed questionnaires and telephone interviews to assess PD status. FOUND follow-up continued when LABS-PD in-person visits ended in 2011. Retention and agreement between remote and in-person assessments were determined. In total, 422 of 499 (84.5%) of eligible patients volunteered, AND 96% of participants were retained. Of 60 patients who withdrew consent from LABS-PD, 51 were retained in FOUND. Of 341 patients who were active in LABS-PD, 340 were retained in FOUND (99.7%) when the in-person visits ceased. Exact agreement between remote and in-person assessments was ≥ 80% for diagnosis, disease features (eg, dyskinesias), and PD medication. Correlation between expert-rated and self-reported Unified Parkinson's Disease Rating Scale and Movement Disorder Society Unified Parkinson's Disease Rating Scale, which were examined at times separated by several months, was moderate or substantial for most items. Retention was excellent using remote follow-up of research participants with PD, providing a safety net when combined with in-person visits, and also is effective as a stand-alone assessment method, providing a useful alternative when in-person evaluation is not feasible.

Item does not contain fulltext Mutations in leucine-rich repeat kinase 2 (LRRK2) cause inherited Parkinson disease (PD), and common variants around LRRK2 are a risk factor for sporadic PD. Using protein-protein interaction arrays, we identified BCL2-associated athanogene 5, Rab7L1 (RAB7, member RAS oncogene family-like 1), and Cyclin-G-associated kinase as binding partners of LRRK2. The latter two genes are candidate genes for risk for sporadic PD identified by genome-wide association studies. These proteins form a complex that promotes clearance of Golgi-derived vesicles through the autophagy-lysosome system both in vitro and in vivo. We propose that three different genes for PD have a common biological function. More generally, data integration from multiple unbiased screens can provide insight into human disease mechanisms.

ObjectiveTo investigate the psychometric properties of the Friedreich Ataxia Rating Scale neurologic examination (FARSn) and its subscores, as well as the influence of the modifications resulting in the now widely used modified FARS (mFARS) examination.MethodsBased on cross-sectional FARS data from the FA–Clinical Outcome Measures cohort, we conducted correlation-based psychometric analyses to investigate the interplay of items and subscores within the FARSn/mFARS constructs.ResultsThe results provide support for both the FARSn and the mFARS constructs, as well as individually for their upper limb and lower limb coordination components. The omission of the peripheral nervous system subscore (D) and 2 items of the bulbar subscore (A) in the mFARS strengthens the overall construct compared with the complete FARS.ConclusionsA correlation-based psychometric analysis of the neurologic FARSn score justifies the overall validity of the scale. In addition, omission of items of limited functional significance as created in the mFARS improves the features of the measures. Such information is crucial to the ongoing application of the mFARS in natural history studies and clinical trials. Additional analyses of longitudinal changes will be necessary to fully ascertain its utility, especially in nonambulant patients.

The Movement Disorder Society (MDS) commissioned a revision of the UPDRS with the goals of improving instructions and definitions, more accurately evaluating milder features, and assessing patient-reported outcomes and nonmotor features. To date, no study has evaluated longitudinal changes in components of the MDS-UPDRS over time or correlated these with changes in other scales of various symptoms. We assessed Parts I and II of the MDS-UPDRS (non-Motor and Motor Experiences of Daily Living [nM-EDL, M-EDL]) as well as a number of other scales of motor, cognitive and behavioral function in a large population of patients (n = 383) with early- to mid-stage Parkinson's disease (PD) who had previously participated in a trial of a putative disease-modifying agent. Both parts of a MDS-UPDRS showed significant change over the 3-year follow-up period, with M-EDL scores declining to a greater extent than nM-EDL. Both the scores and their changes over time correlated relatively well with other rating scales of similar disease aspects. Modest correlations with the original version of the UPDRS supported the increased attention to nonmotor symptoms as well as milder levels of severity in the MDS-UPDRS. The M-EDL was much more sensitive to change over time in these early- to mid-stage patients than the original UPDRS Activities of Daily Living (ADL) scale. Finally, we showed no change over time in a small group of individuals with dopamine transporter single-photon emission computed tomography scans without evidence for dopamine deficiency. The nM-EDL and M-EDL components of the MDS-UPDRS provide an effective, relevant measure of change in the broad spectrum of symptoms of PD over the first decade of the disease. © 2013 International Parkinson and Movement Disorder Society

To use optical coherence tomography (OCT) and contrast letter acuity to characterize vision loss in Friedreich ataxia (FRDA). High- and low-contrast letter acuity and neurological measures were assessed in 507 patients with FRDA. In addition, OCT was performed on 63 FRDA patients to evaluate retinal nerve fiber layer (RNFL) and macular thickness. Both OCT and acuity measures were analyzed in relation to genetic severity, neurologic function, and other disease features. High- and low-contrast letter acuity was significantly predicted by age and GAA repeat length, and highly correlated with neurological outcomes. When tested by OCT, 52.7% of eyes (n = 110) had RNFL thickness values below the fifth percentile for age-matched controls. RNFL thickness was significantly lowest for those with worse scores on the Friedreich ataxia rating scale (FARS), worse performance measure composite Z2 scores, and lower scores for high- and low-contrast acuity. In linear regression analysis, GAA repeat length and age independently predicted RNFL thickness. In a subcohort of participants, 21% of eyes from adult subjects (n = 29 eyes) had macular thickness values below the first percentile for age-matched controls, suggesting that macular abnormalities can also be present in FRDA. Low-contrast acuity and RNFL thickness capture visual and neurologic function in FRDA, and reflect genetic severity and disease progression independently. This suggests that such measures are useful markers of neurologic progression in FRDA.

Contains fulltext : 167923.pdf (Publisher’s version ) (Open Access) Autosomal-recessive early-onset parkinsonism is clinically and genetically heterogeneous. The genetic causes of approximately 50% of autosomal-recessive early-onset forms of Parkinson disease (PD) remain to be elucidated. Homozygozity mapping and exome sequencing in 62 isolated individuals with early-onset parkinsonism and confirmed consanguinity followed by data mining in the exomes of 1,348 PD-affected individuals identified, in three isolated subjects, homozygous or compound heterozygous truncating mutations in vacuolar protein sorting 13C (VPS13C). VPS13C mutations are associated with a distinct form of early-onset parkinsonism characterized by rapid and severe disease progression and early cognitive decline; the pathological features were striking and reminiscent of diffuse Lewy body disease. In cell models, VPS13C partly localized to the outer membrane of mitochondria. Silencing of VPS13C was associated with lower mitochondrial membrane potential, mitochondrial fragmentation, increased respiration rates, exacerbated PINK1/Parkin-dependent mitophagy, and transcriptional upregulation of PARK2 in response to mitochondrial damage. This work suggests that loss of function of VPS13C is a cause of autosomal-recessive early-onset parkinsonism with a distinctive phenotype of rapid and severe progression.

Dopamine (DA) transporter (DAT) imaging has been studied as a diagnostic tool for degenerative parkinsonism. Our aim was to measure the prognostic value of imaging for motor and nonmotor outcomes in Parkinson's disease (PD). We prospectively evaluated a Parkinson's cohort after enrollment in a de novo clinical trial with a battery of motor (UPDRS), cognitive (Montreal Cognitive Assessment), and behavioral measures. DAT imaging with [123I][β]-CIT and single-photon emission computerized tomography (SPECT) was performed at baseline and after 22 months. In total, 491 (91%) of the 537 subjects had evidence of DA deficiency on their baseline scan, consistent with PD, and were included in the analyses. The cohort was followed for 5.5 (0.8) years, with a mean duration of diagnosis of 6.3 (1.2). Lower striatal binding at baseline was independently associated with higher risk for clinical milestones and measures of disease severity, including motor-related disability, falling and postural instability, cognitive impairment, psychosis, and clinically important depressive symptoms. Subjects in the bottom quartile for striatal binding, compared to the top quartile, had an odds ratio (95% confidence interval) of 3.3 (1.7, 6.7) for cognitive impairment and 12.9 (2.6, 62.4) for psychosis. Change from baseline in imaging after 22 months was also independently associated with motor, cognitive, and behavioral outcomes. DAT imaging with [123I][β]-CIT and SPECT, shortly after the diagnosis of PD, was independently associated with clinically important long-term motor and nonmotor outcomes. These results should be treated as hypothesis generating and require confirmation. © 2012 Movement Disorder Society

It is not uncommon to have experimental drugs under different stages of development for a given disease area. Methods are proposed for use when another treatment arm is to be added mid-study to an ongoing clinical trial. Monte Carlo simulation was used to compare potential analytical approaches for pairwise comparisons through a difference in means in independent normal populations including 1.) a linear model adjusting for the design change (stage effect), 2.) pooling data across the stages, or 3.) the use of an adaptive combination test. In the presence of intra-stage correlation (or a non-ignorable fixed stage effect), simply pooling the data will result in a loss of power and will inflate the type I error rate. The linear model approach is more powerful, but the adaptive methods allow for flexibility (re-estimating sample size). The flexibility to add a treatment arm to an ongoing trial may result in cost savings as treatments that become ready for testing can be added to ongoing studies.

Background Although cardiac dysfunction is widely accepted as the most common cause of mortality in Friedreich ataxia (FRDA), no studies have evaluated this since the advent of specific clinical and genetic diagnostic criteria. Methods We performed a retrospective study of FRDA patients to determine cause of death followed by a case–control analysis comparing characteristics of deceased patients with living, age- and sex-matched FRDA controls. Results Causes of death were cardiac dysfunction (59%), probable cardiac dysfunction (3.3%), non-cardiac (27.9%) or unknown (9.8%). Compared to non-cardiac deaths, cardiac deaths occurred earlier in the disease course (median 29 vs. 17 years respectively). Congestive heart failure and arrhythmia were common causes of cardiac-related death. Compared to living, matched FRDA controls, deceased patients had longer triplet repeat lengths and higher rates of arrhythmia and dilated cardiomyopathy. The presence of hypertrophic cardiomyopathy did not differ between deceased and living patients. Conclusion Cardiac dysfunction was the most frequent cause of death (59%), most commonly from congestive heart failure or arrhythmia. Arrhythmia and dilated cardiomyopathy were significantly more common in deceased patients compared to matched FRDA controls, while in contrast, the presence of cardiac hypertrophy did not differ. More research is needed to establish the clinical significance of hypertrophy in FRDA.

Adeno-associated viral (AAV) vectors are a rapidly emerging gene therapy platform for the treatment of neurological diseases. In preclinical studies, transgenes encoding therapeutic proteins, microRNAs, antibodies or gene-editing machinery have been successfully delivered to the central nervous system with natural or engineered viral capsids via various routes of administration. Importantly, initial clinical studies have demonstrated encouraging safety and efficacy in diseases such as Parkinson disease and spinal muscular atrophy, as well as durability of transgene expression. Here, we discuss key considerations and challenges in the future design and development of therapeutic AAV vectors, highlighting the most promising targets and recent clinical advances.

Cognitive dysfunction is an important aspect of Parkinson disease (PD) and is increasingly being examined in various large scale PD clinical studies. However, the sensitivity of some of the cognitive measures used for detecting change in cognitive status in early PD patients is not known nor is the relationship between cognitive outcome measures and other motor and non-motor disease characteristics and various demographic parameters in early PD patients. The current analysis of the NET-PD cohort (i.e., untreated patients) was undertaken to: 1) assess which (if any) baseline demographic parameters correlate with baseline cognitive measures and any potential change in cognitive measures over the 12-18 months evaluation period; 2) assess the extent to which cognitive measures employed (i.e., Repeatable Battery for the Assessment of Neuropsychological Status (RBANS), Frontal Assessment Battery (FAB) and Letter-Number Sequencing) are sensitive to change over time; 3) examine whether initiation of symptomatic therapy is associated with change in cognitive status. At baseline, NET-PD subjects had no significant impairment on the assessments employed. Only education and age were significant predictors of cognitive score at baseline. None of the summary measures were indicative of change in cognitive status over the 12-18 months of study. These results suggest either the cognitive domains examined are not affected in the population examined or that more sensitive measures of cognition than those currently employed may need to be considered for use in a large trial setting in which an early, highly educated PD population is studied.

Coenzyme Q10 (CoQ(10)), a potential neuroprotective compound, was previously investigated at a dosage of 600 mg/day in Huntington's disease (HD) patients and demonstrated a trend toward slowing disease progression. Higher CoQ(10) dosages may prove beneficial. We investigated the tolerability and blood levels associated with 1,200, 2,400, and 3,600 mg/day of CoQ(10) in HD and healthy subjects. Twenty-eight subjects (20 HD, 8 healthy) enrolled in a 20-week open-label trial. Subjects started on 1,200 mg/day of CoQ(10), increasing every 4 weeks by 1,200 mg to a maximum dosage of 3,600 mg/day. Monthly evaluations included review of adverse events and CoQ(10) blood levels. Twenty-three subjects (82%) achieved the target dosage of 3,600 mg/day. Six subjects (2 healthy, 4 HD) withdrew prematurely (gastrointestinal (GI) symptoms in 3, worsening HD in 2, and 1 because of a fall). All three serious adverse events occurred in a single subject, and were deemed unrelated to CoQ(10). The most common adverse events seen were GI symptoms. Mean (± SD) CoQ10 blood levels achieved over the course of the trial were as follows: 1.26 ± 1.27 μg/mL (baseline, n = 28), 5.59 ± 2.24 μg/mL (1,200 mg/day, week 4, n = 26), 6.38 ± 3.25 μg/mL (2,400 mg/day, week 8, n = 25), 7.49 ± 4.09 μg/mL (3,600 mg/day, week 12, n = 23), and 6.78 ± 3.36 μg/mL (3,600 mg/day, week 20, n = 20). CoQ(10) was well tolerated with over 80% of subjects achieving the target dosage. Dosages of 2,400 mg/day may provide the best balance between tolerability and blood level achieved. Further studies examining the efficacy of 2,400 mg/day are planned.

More than 30 phase II or III clinical trials have been carried out in amyotrophic lateral sclerosis (ALS). Only riluzole, however, has been shown to extend survival and/or time to tracheostomy. Many early ALS trials lacked solid pharmacodynamic and pharmacokinetic data for the treatment being tested, challenging the interpretation of the efficacy and pathway relevance. Understanding of the genetics and pathophysiology of ALS has improved considerably in the past decade, but biomarkers of disease activity remain lacking. A more efficient approach to early phase clinical trials is needed to accelerate the identification of useful agents for ALS. Here we summarize our current thinking about phase II design options and the potential benefits of a clinical trial network for phase II trials in ALS.

Long-term follow up is necessary to understand the natural history of treated Parkinson's disease (PD). The Longitudinal and Biomarker Study in PD (LABS-PD) is an observational study designed to prospectively measure the evolution of motor and non-motor features of PD and sample promising biomarkers from early to late stage illness. LABS-PD is organized on the premise that cohorts from completed clinical trials can be re-recruited for long-term follow up. LABS-PD will eventually contain multiple cohorts, but to test the feasibility of the strategy, we examined enrollment and biomarker sampling in the initial cohorts. The first PD cohort (PostCEPT) comes from the de novo clinical trial of a mixed lineage kinase inhibitor (PRECEPT). We assessed the recruitment from PRECEPT to PostCEPT, the ability to link data from the two studies, and sample collection for a variety of biomarkers. A total of 537 of 709 eligible PRECEPT subjects (76%) enrolled in PostCEPT; 509 (95%) had repeat dopamine transporter imaging. PRECEPT clinical and imaging data were successfully linked to PostCEPT, to provide 3 to 4 year follow-up. A biomarker sub-study enrolled over 100 PD cases from PostCEPT and 100 controls to measure olfaction and blood markers of gene expression, alpha-synuclein, and proteomic profiles. We were also successful in linking clinical and biomarker data to DNA samples that have been collected in the publicly accessible Coriell repository. The PostCEPT cohort and associated studies strongly support the feasibility of the LABS-PD approach of retaining and repurposing clinical trial cohorts to collect longitudinal clinical and biomarker data.

The decision to initiate invasive, first-in-human trials involving Parkinson’s disease presents a vexing ethical challenge. Such studies present significant surgical risks, and high degrees of uncertainty about intervention risks and biological effects. We argue that maintaining a favorable risk-benefit balance in such circumstances requires a higher than usual degree of confidence that protocols will lead to significant direct and/or social benefits. One critical way of promoting such confidence is through the application of stringent evidentiary standards for preclinical studies. We close with a series of recommendations for strengthening the internal and external validity of preclinical studies, reducing their tendency toward optimism and publication biases, and improving the knowledge base used to design and evaluate preclinical studies.

Little is known about the course of depressive symptoms in Parkinson's disease (PD). We studied the course of clinically significant depressive symptoms using data from two clinical trials that followed 413 early, untreated PD subjects for 12 to 18 months. We measured depressive symptoms with the 15-item geriatric depression scale (GDS-15); a score of > or =5 indicates clinically significant depressive symptoms. We used a time-dependent Cox model to examine the association between demographic variables, PD severity, and medication use on the time to resolution of depressive symptoms. One hundred fourteen of 413 (27.6%) subjects were screened positive for depression during the study, with a median GDS-15 score of 6, indicating mild symptoms. Within 6 months, 47% of subjects experienced remission of clinically significant depressive symptoms. Subjects with mild depressive symptoms were more likely to develop moderate to severe depressive symptoms (GDS > or = 10) than those without prior symptoms (relative risk = 6.16). Increasing severity of depressive symptoms, older age, and longer PD duration predicted a lower likelihood of symptom resolution (hazard ratios 0.83-0.92). Mild depressive symptoms have a variable course, with remission and development of more sustained and severe symptoms occurring over time. More severe depressive symptoms may herald a protracted course.

Background Parkinson’s disease (PD) is the second most common neurodegenerative disorder. People with PD, their families, scientists, health care providers, and the general public are increasingly interested in identifying environmental contributors to PD risk. Methods In June 2007, a multidisciplinary group of experts gathered in Sunnyvale, California, USA, to assess what is known about the contribution of environmental factors to PD. Results We describe the conclusions around which they came to consensus with respect to environmental contributors to PD risk. We conclude with a brief summary of research needs. Conclusions PD is a complex disorder, and multiple different pathogenic pathways and mechanisms can ultimately lead to PD. Within the individual there are many determinants of PD risk, and within populations, the causes of PD are heterogeneous. Although rare recognized genetic mutations are sufficient to cause PD, these account for < 10% of PD in the U.S. population, and incomplete penetrance suggests that environmental factors may be involved. Indeed, interplay among environmental factors and genetic makeup likely influences the risk of developing PD. There is a need for further understanding of how risk factors interact, and studying PD is likely to increase understanding of other neurodegenerative disorders.

The objective of this study was to examine the relationship between CAG repeat length (CAGn) and clinical progression in patients with Huntington's disease (HD). There are conflicting reports about the relationship between CAGn and clinical progression of HD. We conducted an analysis of data from the Coenzyme Q10 and Remacemide Evaluation in Huntington's Disease (CARE-HD) clinical trial. We modeled progression over 30 months on the Unified Huntington's Disease Rating Scale (UHDRS) and supplemental neuropsychological and behavioral tests using multiple linear regression. Mean subject age was 47.9 +/- 10.5 years and mean CAGn was 45.0 +/- 4.1. Multiple linear regression revealed statistically significant associations between CAGn and worsening on several motor, cognitive, and functional outcomes, but not behavioral outcomes. Many effects were clinically important; 10 additional CAG repeats were associated with an 81% increase in progression on the Independence Scale. These associations were not observed in the absence of age adjustment. Age at the time of assessment confounds the association between CAGn and progression. Adjusting for age shows that longer CAGn is associated with greater clinical progression of HD. This finding may account for the variable results from previous studies examining CAGn and progression. Adjusting for CAGn may be important for clinical trials.

Cognitive impairment is common in Parkinson's disease (PD) and can occur early in the disease course. No effective screening test exists for detection of early or mild cognitive impairment in PD. We examined the Montreal Cognitive Assessment (MoCA) as a screening tool for cognitive dysfunction in PD. The test-retest intraclass correlation coefficient was 0.79 and the interrater intraclass correlation coefficient was 0.81. The correlation coefficient between the MoCA and a neuropsychologic battery was 0.72. The MoCA is reliable and valid in the PD population and warrants further study as a screening tool for cognitive dysfunction.