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Background: Episodic ataxias are rare neurological disorders characterized by recurring episodes of imbalance and coordination difficulties. Obtaining definitive molecular diagnoses poses challenges, as clinical presentation is highly heterogeneous, and literature on the underlying genetics is limited. While the advent of high-throughput sequencing technologies has significantly contributed to Mendelian disorders genetics, interpretation of variants of uncertain significance and other limitations inherent to individual methods still leaves many patients undiagnosed. This study aimed to investigate the utility of multi-omics for the identification and validation of molecular candidates in a cohort of complex cases of ataxia with episodic presentation. Methods: Eight patients lacking molecular diagnosis despite extensive clinical examination were recruited following standard genetic testing. Whole genome and RNA sequencing were performed on samples isolated from peripheral blood mononuclear cells. Integration of expression and splicing data facilitated genomic variants prioritization. Subsequently, long-read sequencing played a crucial role in the validation of those candidate variants. Results: Whole genome sequencing uncovered pathogenic variants in four genes ( SPG7 , ATXN2 , ELOVL4 , PMPCB ). A missense and a nonsense variant, both previously reported as likely pathogenic, configured in trans in individual #1 ( SPG7 : c.2228T>C/p.I743T, c.1861C>T/p.Q621*). An ATXN2 microsatellite expansion (CAG 32 ) in another late-onset case. In two separate individuals, intronic variants near splice sites ( ELOVL4 : c.541 + 5G>A; PMPCB : c.1154 + 5G>C) were predicted to induce loss-of-function splicing, but had never been reported as disease-causing. Long-read sequencing confirmed the compound heterozygous variants configuration, repeat expansion length, as well as splicing landscape for those pathogenic variants. A potential genetic modifier of the ATXN2 expansion was discovered in ZFYVE26 (c.3022C>T/p.R1008*). Conclusion: Despite failure to identify pathogenic variants through clinical genetic testing, the multi-omics approach enabled the molecular diagnosis in 50% of patients, also giving valuable insights for variant prioritization in remaining cases. The findings demonstrate the value of long-read sequencing for the validation of candidate variants in various scenarios. Our study demonstrates the effectiveness of leveraging complementary omics technologies to unravel the underlying genetics in patients with unresolved rare diseases such as ataxia. Molecular diagnoses not only hold significant promise in improving patient care management, but also alleviates the burden of diagnostic odysseys, more broadly enhancing quality of life., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The author(s) declared that they were an editorial board member of Frontiers, at the time of submission. This had no impact on the peer review process and the final decision., (Copyright © 2024 Audet, Triassi, Gelinas, Legault-Cadieux, Ferraro, Duquette and Tetreault.)

Background and Objectives: The understanding of the natural history of Friedreich ataxia (FRDA) has improved considerably recently, but patterns of neurologic deterioration are not fully clarified, compromising the assessment of the clinical relevance of effects and guidance for study design. The goal of this study was to acknowledge the broad genetic diversity of the population, especially for younger individuals, and to provide analyses stratified by age to guide population selection in future studies., Methods: Based on a large natural history study, the FRDA Clinical Outcome Measures study that at the current data cut enrolled 1,115 participants, followed up for 5,287 yearly visits, we present results from the modified FRDA Rating Scale and its subscores. The secondary outcomes included the patient-reported activities of daily living scale, the timed 25-foot walk, and the 9-hole peg test. Long-term progression was modeled using slope analyses within early-onset, typical-onset, intermediate-onset, and late-onset FRDA. To reflect recruitment in clinical trials, short-term changes were analyzed within age-based subpopulations. All analyses were stratified by ambulation status., Results: Long-term progression models stratified by disease severity indicated highly differential disease progression, especially at earlier ages at onset. In the ambulatory phase, decline was driven by axial items assessed by the Upright Stability subscore of the mFARS. The analyses of short-term changes showed slower progression with increasing population age due to decreasing genetic severity. Future clinical studies could reduce population diversity, interpatient variability, and the risk of imbalanced treatment groups by selecting the study population based on the functional capacity (e.g., ambulatory status) and by strict age-based stratification., Discussion: The understanding of the diversity within FRDA populations and their patterns of functional decline provides an essential foundation for future clinical trial design including patient selection and facilitates the interpretation of the clinical relevance of progression detected in FRDA., (Copyright © 2022 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of the American Academy of Neurology.)

Objectives: Disease-modifying therapies in development for Huntington's disease (HD) may require specialised administration and additional resource capacity. We sought to understand current and future capacity for HD management in Canada considering the possible introduction of an intrathecal (IT) disease-modifying treatment (DMT)., Design, Setting and Participants: Using a case study, mixed methods framework, online surveys followed by semistructured interviews were conducted in late 2020 and early 2021. Neurologists from Canadian HD (n=16) and community (n=11) centres and social workers (n=16) were invited to complete online surveys assessing current HD management and potential capacity to support administration of an IT DMT., Outcome Measures: Survey responses, anticipated demand and assumed resource requirements were modelled to reveal capacity to treat (ie, % of eligible patients) by centre. Resource bottlenecks and incremental support required (full-time equivalent, FTE) were also determined., Results: Neurologists from 15/16 HD centres and 5/11 community centres, plus 16/16 social workers participated. HD centres manage 94% of patients with HD currently seeking care in Canada, however, only 20% of IT DMT-eligible patients are currently seen by neurologists. One-third of centres have no access to nursing support. The average national incremental nursing, room, neurologist and social worker support required to provide IT DMT to all eligible patients is 0.73, 0.36, 0.30 and 0.21 FTE per HD centre, respectively. At peak demand, current capacity would support the treatment of 6% of IT DMT-eligible patients. If frequency of administration is halved, capacity for IT-DMT administration only increases to 11%., Conclusions: In Canada, there is little to no capacity to support the administration of an IT DMT for HD. Current inequitable and inadequate resourcing will require solutions that consider regional gaps and patient needs., Competing Interests: Competing interests: AB reports employment by Huntington Society of Canada, which has received unrestricted grants from F. Hoffmann-La Roche, uniQure, Prilenia, PTC Therapeutics, Novartis, Triplet Therapeutics, and Wave Life Sciences; and has participated in research projects with F. Hoffmann-La Roche. SC reports receiving honoraria from F. Hoffmann-La Roche. BRL reports receiving personal compensation in the 3 past years as a paid scientific advisor or consultant to Novartis, Roche Canada, Remix Therapeutics, Sintetica, PTC Therapeutics, sRNAlytics, Teva, Triplet Therapeutics, F. Hoffmann-La Roche, Pfizer, Takeda, Design Tx, and uniQure regarding the development of new therapies for Huntington disease and similar disorders; receiving contract research funding from F. Hoffmann-La Roche, Teva, and uniQure to perform basic research projects in mouse models of Huntington disease; and receiving compensation for administrative expenses as the Co-Editor-in-Chief of the Journal of Huntington’s Disease. SC reports receiving honoraria from F. Hoffmann-La Roche. BRL has patents related to and is a co-founder and CEO of Incisive Genetics Inc. NB and JWW are employed by the study sponsor, F. Hoffmann-La Roche Ltd. KS reports receiving research funding from F. Hoffmann-La Roche and Prilenia Therapeutics., (© Author(s) (or their employer(s)) 2022. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Importance: Essential tremor (ET) is one of the most common movement disorders, affecting 5% of the general population older than 65 years. Common variants are thought to contribute toward susceptibility to ET, but no variants have been robustly identified., Objective: To identify common genetic factors associated with risk of ET., Design, Setting, and Participants: Case-control genome-wide association study. Inverse-variance meta-analysis was used to combine cohorts. Multicenter samples collected from European populations were collected from January 2010 to September 2019 as part of an ongoing study. Included patients were clinically diagnosed with or reported having ET. Control individuals were not diagnosed with or reported to have ET. Of 485 250 individuals, data for 483 054 passed data quality control and were used., Main Outcomes and Measures: Genotypes of common variants associated with risk of ET., Results: Of the 483 054 individuals included, there were 7177 with ET (3693 [51.46%] female; mean [SD] age, 62.66 [15.12] years), and 475 877 control individuals (253 785 [53.33%] female; mean [SD] age, 56.40 [17.6] years). Five independent genome-wide significant loci and were identified and were associated with approximately 18% of ET heritability. Functional analyses found significant enrichment in the cerebellar hemisphere, cerebellum, and axonogenesis pathways. Genetic correlation (r), which measures the degree of genetic overlap, revealed significant common variant overlap with Parkinson disease (r, 0.28; P = 2.38 × 10-8) and depression (r, 0.12; P = 9.78 × 10-4). A separate fine-mapping of transcriptome-wide association hits identified genes such as BACE2, LRRN2, DHRS13, and LINC00323 in disease-relevant brain regions, such as the cerebellum., Conclusions and Relevance: The results of this genome-wide association study suggest that a portion of ET heritability can be explained by common genetic variation and can help identify new common genetic risk factors for ET.

Background: Several monogenic causes for isolated dystonia have been identified, but they collectively account for only a small proportion of cases. Two genome-wide association studies have reported a few potential dystonia risk loci; but conclusions have been limited by small sample sizes, partial coverage of genetic variants, or poor reproducibility., Objective: To identify robust genetic variants and loci in a large multicenter cervical dystonia cohort using a genome-wide approach., Methods: We performed a genome-wide association study using cervical dystonia samples from the Dystonia Coalition. Logistic and linear regressions, including age, sex, and population structure as covariates, were employed to assess variant- and gene-based genetic associations with disease status and age at onset. We also performed a replication study for an identified genome-wide significant signal., Results: After quality control, 919 cervical dystonia patients compared with 1491 controls of European ancestry were included in the analyses. We identified one genome-wide significant variant (rs2219975, chromosome 3, upstream of COL8A1, P-value 3.04 × 10 -8 ). The association was not replicated in a newly genotyped sample of 473 cervical dystonia cases and 481 controls. Gene-based analysis identified DENND1A to be significantly associated with cervical dystonia (P-value 1.23 × 10 -6 ). One low-frequency variant was associated with lower age-at-onset (16.4 ± 2.9 years, P-value = 3.07 × 10 -8 , minor allele frequency = 0.01), located within the GABBR2 gene on chromosome 9 (rs147331823)., Conclusion: The genetic underpinnings of cervical dystonia are complex and likely consist of multiple distinct variants of small effect sizes. Larger sample sizes may be needed to provide sufficient statistical power to address the presumably multi-genic etiology of cervical dystonia. © 2021 International Parkinson and Movement Disorder Society., (© 2021 International Parkinson and Movement Disorder Society.)

Niemann-Pick type C (NP-C) disease is an autosomal recessive disease caused by variants in the NPC1 or NPC2 genes. It has a large range of symptoms depending on age of onset, thus making it difficult to diagnose. In adults, symptoms appear mainly in the form of psychiatric problems. The prevalence varies from 0.35 to 2.2 per 100,000 births depending on the country. The aim of this study is to calculate the estimated prevalence of NP-C in Quebec to determine if it is underdiagnosed in this population. The CARTaGENE database is a unique database that regroups individuals between 40 and 69 years old from metropolitan regions of Quebec. RNA-sequencing data was available for 911 individuals and exome sequencing for 198 individuals. We used a bioinformatic pipeline on those individuals to extract the variants in the NPC1/2 genes. The prevalence in Quebec was estimated assuming Hardy-Weinberg Equilibrium. Two pathogenic variants were used. The variant p.Pro543Leu was found in three heterozygous individuals that share a common haplotype, which suggests a founder French-Canadian pathogenic variant. The variant p.Ile1061Thr was found in two heterozygous individuals. Both variants have previously been reported and are usually associated with infantile onset. The estimated prevalence calculated using those two variants is 0.61:100,000 births. This study represents the first estimate of NP-C in Quebec. The estimated prevalence for NP-C is likely underestimated due to misdiagnosis or missed cases. It is therefore important to diagnose all NP-C patients to initiate early treatment., (© 2021. The Author(s).)

Progressive supranuclear palsy (PSP) and corticobasal syndrome (CBS; the most common phenotype of corticobasal degeneration) are tauopathies with a relentless course, usually starting in the mid-60s and leading to death after an average of 7 years. There is as yet no specific or disease-modifying treatment. Clinical deficits in PSP are numerous, involve the entire neuraxis, and present as several discrete phenotypes. They center on rigidity, bradykinesia, postural instability, gait freezing, supranuclear ocular motor impairment, dysarthria, dysphagia, incontinence, sleep disorders, frontal cognitive dysfunction, and a variety of behavioral changes. CBS presents with prominent and usually asymmetric dystonia, apraxia, myoclonus, pyramidal signs, and cortical sensory loss. The symptoms and deficits of PSP and CBS are amenable to a variety of treatment strategies but most physicians, including many neurologists, are reluctant to care for patients with these conditions because of unfamiliarity with their multiplicity of interacting symptoms and deficits. CurePSP, the organization devoted to support, research, and education for PSP and CBS, created its CurePSP Centers of Care network in North America in 2017 to improve patient access to clinical expertise and develop collaborations. The directors of the 25 centers have created this consensus document outlining best practices in the management of PSP and CBS. They formed a writing committee for each of 12 sub-topics. A 4-member Steering Committee collated and edited the contributions. The result was returned to the entire cohort of authors for further comments, which were considered for incorporation by the Steering Committee. The authors hope that this publication will serve as a convenient guide for all clinicians caring for patients with PSP and CBS and that it will improve care for patients with these devastating but manageable disorders., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Bluett, Pantelyat, Litvan, Ali, Apetauerova, Bega, Bloom, Bower, Boxer, Dale, Dhall, Duquette, Fernandez, Fleisher, Grossman, Howell, Kerwin, Leegwater-Kim, Lepage, Ljubenkov, Mancini, McFarland, Moretti, Myrick, Patel, Plummer, Rodriguez-Porcel, Rojas, Sidiropoulos, Sklerov, Sokol, Tuite, VandeVrede, Wilhelm, Wills, Xie and Golbe.)

Niemann-Pick disease type C (NPC) is a treatable autosomal recessive neurodegenerative condition which leads to a variety of progressive manifestations. Despite most cases being diagnosed at a young age, disease prevalence may be underestimated, especially in adults, and interpretation of NPC1 and NPC2 variants can be difficult. This study aims to identify potential pathogenic variants in a large cohort of healthy individuals and classify their risk of pathogenicity to assist with future interpretation of variants. The CARTaGENE (CaG) cohort was used to identify possible variants of NPC1 and NPC2. Nine-hundred and eleven RNA samples and 198 exome sequencing were screened for genetic variants through a bio-informatic pipeline performing alignment and variant calling. The identified variants were analyzed using annotations for allelic frequency, pathogenicity and conservation scores. The ACMG guidelines were used to classify the variants. These were then compared to existing databases and previous studies of NPC prevalence, including the Tübingen NPC database. Thirty-two distinct variants were identified after running the samples in the RNA-sequencing pipeline, two of which were classified as pathogenic and 21 of which were not published previously. Furthermore, 46 variants were both identified in our population and with the Tübingen database, the majority of which were of uncertain significance. Ten additional variants were found in our exome-sequencing sample. This study of a sample from a population living in Quebec demonstrates a variety of rare variants, some of which were already described in the literature as well as some novel variants. Classifying these variants is arduous given the scarcity of available literature, even so in a population of healthy individuals. Yet using this data, we were able to identify two pathogenic variants within our population and several new variants not previously identified.

Antagonising the serotonin 2A (5-HT 2A ) receptor is an efficacious way to alleviate dyskinesia and psychosis in Parkinson's disease (PD). However, previous research indicates that there might be a limit to the effects conferred by this approach. 5-HT 2A receptors were shown to form hetero-dimers with metabotropic glutamate 2 (mGlu 2 ) receptors, in which 5-HT 2A blockade and mGlu 2 activation elicit equivalent effects at the downstream signalling level. We have previously shown that mGlu 2 activation reduces both dyskinesia and psychosis-like behaviours (PLBs) induced by L-3,4-dihydroxyphenylalanine (l-DOPA), in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-lesioned primate. Here, we hypothesised that concurrent 5-HT 2A antagonism and mGlu 2 activation would provide greater anti-dyskinetic and anti-psychotic benefits than either approach alone. We conducted 3 series of experiments in the MPTP-lesioned marmoset. In the first series of experiments, the mGlu 2 positive allosteric modulator LY-487,379 and the 5-HT 2A antagonist EMD-281,014, either alone or in combination, were added to l-DOPA. In the second series of experiments, the mGlu 2/3 orthosteric agonist LY-354,740 and EMD-281,014, either alone or in combination, were added to l-DOPA. In the last series of experiments, we investigated whether mGlu 2 blockade would diminish the effects of antagonising 5-HT 2A receptors. To this end, the mGlu 2/3 orthosteric antagonist LY-341,495 and EMD-281,014, either alone or in combination, were added to l-DOPA. We found that the anti-dyskinetic effect of the combination LY-487,379/EMD-281,014 was greater than the ones conferred by LY-487,379 (by 35%, P < 0.05) and EMD-281,014 (by 38%, P < 0.01). The anti-dyskinetic and anti-psychotic effects of the combination LY-354,740/EMD-281,014 were also greater than the ones conferred by LY-354,740 (by 57% for dyskinesia and 54% for PLBs, both P < 0.001) and EMD-281,014 (by 61% for dyskinesia and 53% for PLBs, both P < 0.001). The anti-parkinsonian action of l-DOPA was maintained with all treatments. Lastly, the addition of LY-341,495 abolished the therapeutic effects of EMD-281,014 on dyskinesia and PLBs. Our results suggest that mGlu 2 activation may enhance the anti-dyskinetic and anti-psychotic effects of 5-HT 2A blockade and could provide relief to PD patients with dyskinesia and psychotic symptoms beyond what can be achieved with current therapies., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Objectives: The treatment of Parkinson disease (PD) psychosis remains a challenge. Only a few treatments eliciting significant relief of psychotic symptoms have passed the test of randomized controlled trials., Methods: Here, we conducted a review of the literature on the effect of antidepressants on PD psychosis. Because there is no randomized controlled trial that assessed the antipsychotic effects of antidepressants in PD, only case reports, case series, and open-label trials were available to review. Because of the scarce literature, statistical analysis could not be performed., Results: The following antidepressants alleviated hallucinations in PD: amoxapine, citalopram, clomipramine, escitalopram, mianserin, mirtazapine, and venlafaxine. The antidepressants were generally well tolerated, with the exception of amoxapine, which exacerbated parkinsonism., Conclusions: Whereas the conclusions that can be drawn on the efficacy of antidepressants at reducing PD psychosis are limited because of the poor quality of the reported studies, it is encouraging to notice that there are positive anecdotal reports. Further studies are needed to confirm the potential of these drugs and also to determine if a subtype of patients or of psychotic features may be more likely to be improved by antidepressants.

Psychosis and dyskinesia significantly diminish the quality of life of patients with advanced Parkinson's disease (PD). Available treatment options are unfortunately few and their use is limited by adverse effects. We have recently shown that activation of metabotropic glutamate 2 and 3 (mGlu2/3) receptors produced significant relief of L-3,4-dihydroxyphenylalanine (L-DOPA)-induced psychosis-like behaviours (PLBs) and dyskinesia in experimental models of PD. Here, using the highly-selective mGlu2 positive allosteric modulator (PAM) LY-487,379, we seek to determine the contribution of selective mGlu2 activation on both L-DOPA-induced PLBs and dyskinesia, in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-lesioned primate. We first determined the pharmacokinetic (PK) profile of LY-487,379 in the common marmoset, following which we administered it (0.1, 1 and 10 mg/kg) or its vehicle to 6 MPTP-lesioned marmosets previously exposed to L-DOPA to elicit stable PLBs and dyskinesia. We found that LY-487,379 provided a ≈45% reduction of the global PLBs observed and reduced global dyskinesia score by ≈ 55%. Moreover, LY-487,379 enhanced the anti-parkinsonian effect of L-DOPA, by reducing global parkinsonian score by ≈ 15%. Our data suggest that selective mGlu2 positive allosteric modulation with LY-487,379 may represent a potential therapeutic approach to alleviate both L-DOPA-induced PLBs and dyskinesia in PD., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Background: Genetic, biologic and clinical data suggest that Parkinson's disease (PD) is an umbrella for multiple disorders with clinical and pathological overlap, yet with different underlying mechanisms. To better understand these and to move towards neuroprotective treatment, we have established the Quebec Parkinson Network (QPN), an open-access patient registry, and data and bio-samples repository., Objective: To present the QPN and to perform preliminary analysis of the QPN data., Methods: A total of 1,070 consecutively recruited PD patients were included in the analysis. Demographic and clinical data were analyzed, including comparisons between males and females, PD patients with and without RBD, and stratified analyses comparing early and late-onset PD and different age groups., Results: QPN patients exhibit a male:female ratio of 1.8:1, an average age-at-onset of 58.6 years, an age-at-diagnosis of 60.4 years, and average disease duration of 8.9 years. REM-sleep behavior disorder (RBD) was more common among men, and RBD was associated with other motor and non-motor symptoms including dyskinesia, fluctuations, postural hypotension and hallucinations. Older patients had significantly higher rates of constipation and cognitive impairment, and longer disease duration was associated with higher rates of dyskinesia, fluctuations, freezing of gait, falls, hallucinations and cognitive impairment. Since QPN's creation, over 60 studies and 30 publications have included patients and data from the QPN., Conclusions: The QPN cohort displays typical PD demographics and clinical features. These data are open-access upon application (http://rpq-qpn.ca/en/), and will soon include genetic, imaging and bio-samples. We encourage clinicians and researchers to perform studies using these resources.

Background: More than 75% of Parkinson's disease (PD) patients will develop dementia. Previous studies on the cognitive predictors of dementia in PD had some methodological limitations and the cognitive tests identified as good predictors vary greatly., Objective: This prospective cohort study aims to identify the optimal cognitive predictors of dementia in PD using complementary statistical methods., Methods: Eighty PD patients without dementia underwent polysomnographic recording, a neurological examination, and a complete neuropsychological assessment at baseline. They were then followed for a mean of 4.3 years. Baseline group comparisons and survival analyses were used to identify optimal cognitive predictors. Moreover, patients who developed dementia were pair-matched at baseline according to age, sex, and education to healthy controls (2 : 1), and receiver operating characteristic curves were calculated for cognitive tests., Results: At follow-up, 23 patients (29%) developed dementia. PD patients who developed dementia had poorer baseline performance and a higher proportion of clinically impaired performance on several cognitive tests. Impaired baseline performance on the Block Design subtest was the best independent predictor of dementia (HR = 8). Moreover, the Trail Making Test part B (time) and Verbal Fluency (semantic) had the best psychometric properties (area under the curve >0.90) for identifying PD patients at risk of dementia., Conclusion: The present study identified three cognitive tests as the most accurate to detect individuals with PD at high risk of developing dementia.

We aimed to investigate cortical and subcortical brain alterations in people with Parkinson's disease with polysomnography-confirmed rapid eye movement (REM) sleep behavior disorder (RBD). Thirty people with Parkinson's disease, including 15 people with RBD, were recruited and compared with 41 healthy controls. Surface-based cortical and subcortical analyses were performed on T1-weighted images to investigate thickness and shape abnormalities between groups, and voxel-based and deformation-based morphometry were performed to investigate local volume. Correlations were performed in patients to investigate the structural correlates of motor activity during REM sleep. People with RBD showed cortical thinning in the right perisylvian and inferior temporal cortices and shape contraction in the putamen compared with people without RBD. Compared with controls, people with RBD had extensive cortical thinning and volume loss, brainstem volume was reduced, and shape contraction was found in the basal ganglia and hippocampus. In comparison to controls, people without RBD showed more restricted thinning in the sensorimotor, parietal, and occipital cortices, reduced volume in the brainstem, temporal and more posterior areas, and shape contraction in the pallidum and hippocampus. In Parkinson's disease, higher tonic and phasic REM sleep motor activity was associated with contraction of the thalamic surface, extensive cortical thinning, and subtle volume reduction in the middle temporal gyrus. In Parkinson's disease, the presence of RBD is associated with extensive cortical and subcortical abnormalities, suggesting more severe neurodegeneration in people with RBD. This provides potential neuroanatomical correlates for the more severe clinical phenotype reported in people with Parkinson's disease with RBD., (© Sleep Research Society 2019. Published by Oxford University Press on behalf of the Sleep Research Society. All rights reserved. For permissions, please e-mail journals.permissions@oup.com.)

Drugs modulating the metabotropic glutamate type 2 receptor (mGluR 2 ) activity may have therapeutic benefits in treating a large spectrum of neuro-psychiatric disorders, from schizophrenia to Parkinson's disease, both as a symptomatic therapy and potential disease-modifying paradigm. LY-487,379 is a highly selective mGluR 2 positive allosteric modulator that is widely used to study mGluR 2 function using experimental animal models. The common marmoset is a small primate that has long been used in neuroscience. However, given its small size and small circulating blood volume, conducting studies to determine the PK profile of LY-487,379 is challenging. We developed and validated a sensitive and selective analytical method that enables quantification of LY-487,379 using a limited volume of plasma (10 μL). The analytical method consists of protein precipitation followed by high-performance liquid chromatography with heat assisted electrospray ionization mass spectrometry (HPLC-HESI-MS/MS). The chromatographic separation was achieved using gradient elution with a mobile phase consisting of acetonitrile and 0.01% formic acid in water on a Thermo Scientific Aquasil C18 analytical column (100 × 2.1 mm I.D., 5 μm) operating at 40 °C and at a flow rate of 300 μL/min. The method displays a linear relationship ranging from 0.2 to 100 ng/mL. Intra- and inter-day relative standard deviations are <1.4% and 7.9%, respectively and the relative error ranged from -6.9 to 9.7%. The method was used to quantify LY-487,379 in both rat and marmoset plasma, and PK parameters were determined after a single subcutaneous dose of 1.0 mg kg -1 in both species and significant differences in C max , AUC and T 1/2 were observed., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Trazodone is a clinically available anti-depressant that exhibits affinity for serotonin 1A and 2A receptors, as well as for alpha-adrenoceptors, suggesting that it may be useful to treat L-3,4-dihydroxyphenylalanine (L-DOPA)-induced dyskinesia and psychosis that are encountered in advanced Parkinson's disease (PD). Here, we investigated the anti-dyskinetic and anti-psychotic effects of trazodone in the parkinsonian non-human primate. 6 common marmosets were rendered parkinsonian by administration of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Following repeated administration of L-DOPA to induce stable dyskinesia and psychosis-like behaviours (PLBs), trazodone (0.1, 1 and 10 mg/kg) or vehicle was administered in combination with L-DOPA and its effects on dyskinesia, PLBs and parkinsonism were determined. The addition of trazodone 10 mg/kg to L-DOPA reduced peak dose dyskinesia by ≈ 39% (P < 0.01) and peak dose PLBs by ≈ 17% (P < 0.01). However, parkinsonian disability was significantly worsened by trazodone 10 mg/kg (P < 0.05) and duration of anti-parkinsonian action was diminished by ≈ 21% (P < 0.05). Our results suggest that trazodone may be effective in alleviating L-DOPA-induced dyskinesia and psychosis in PD, but its deleterious effect on motor function is a concern and may limit its tolerability and usefulness in clinical settings.

Background: In Parkinson's disease cognitive impairment is an early nonmotor feature, but it is still unclear why some patients are able to maintain their cognitive performance at normal levels, as quantified by neuropsychological tests, whereas others cannot. The objectives of this study were to perform a cross-sectional study and analyze the white matter changes in the cognitive and motor bundles in patients with Parkinson's disease., Methods: Sixteen Parkinson's disease patients with normal cognitive performance, 19 with mild cognitive impairment (based on their performance of 1.5 standard deviations below the healthy population mean), and 16 healthy controls were compared with respect to their tractography patterns between the cortical cognitive / motor regions and subcortical structures, using high angular resolution diffusion imaging and constrained spherical deconvolution computation., Results: Motor bundles showed decreased apparent fiber density in both PD groups, associated with a significant increase in diffusivity metrics, number of reconstructed streamlines, and track volumes, compared with healthy controls. By contrast, in the cognitive bundles, decreased fiber density in both Parkinson's groups was compounded by the absence of changes in diffusivity in patients with normal cognition, whereas patients with cognitive impairment had increased diffusivity metrics, lower numbers of reconstructed streamlines, and lower track volumes., Conclusions: Both PD groups showed similar patterns of white matter neurodegeneration in the motor bundles, whereas cognitive bundles showed a distinct pattern: Parkinson's patients with normal cognition had white matter diffusivity metrics similar to healthy controls, whereas in patients with cognitive impairment white matter showed a neurodegeneration pattern. © 2018 International Parkinson and Movement Disorder Society., (© 2018 International Parkinson and Movement Disorder Society.)

Objective: To assess the contribution of variants in STK32B , PPARGC1A , and CTNNA3 as essential tremor (ET) predisposing factors following their association in a 2-stage genome-wide association study (GWAS)., Methods: The coding regions of these genes was examined for the presence of rare variants using two approaches: (1) Looking at whole-exome and whole-genome sequencing data of 14 autosomal dominant multiplex ET families. (2) Conducting a targeted massive parallel sequencing to examine the three genes in cohorts of 269 ET cases and 287 control individuals. The cumulative impact of rare variants was assessed using SKAT-O analyses using (1) all variants, (2) only rare variants, and (3) only the rare variants altering the mRNA., Results: Thirty-four variants were identified. No difference emerged regarding the distributions of individual variants (or gene) between cases and controls., Conclusion: No rare exonic variants further validated one of these genes as a risk factor for ET. The recent GWAS offers promising avenues, but the genetic heterogeneity of ET is nonetheless challenging for the validation of risk factors, and ultimately larger cohorts of cases should help to overcome this task.

LY-354,740 (eglumegad) is a selective and potent agonist of the metabotropic glutamate group II receptors (mGluR2,3) that has already entered clinical trials as a potential anti-psychotic agent and therefore has well-documented pharmacokinetic (PK), safety and tolerability profiles in human. Whereas its development as an anti-psychotic agent has not been pursued, LY-354,740 may have potential in other neuroscience-related fields, notably anxiety and neuro-protection. The common marmoset is a small primate that has long been used in neuroscience. However, given its small size and small circulating blood volume, conducting PK studies to determine the therapeutic effectiveness of LY-354,740 at clinically-relevant doses is challenging. Here, we have developed and validated a simple, sensitive and selective analytical method that enables quantification of LY-354,740 using a small volume of plasma. The analytical method consisted of protein precipitation followed by high-performance liquid chromatography with heat assisted electrospray ionisation mass spectrometry (UHPLC-HESI-MS/MS). The chromatographic separation was achieved using gradient elution with a mobile phase consisting of acetonitrile and 10mM ammonium formate (pH 3) on a Thermo Scientific Acclaim Trinity P1 analytical column (100x3.0mm I.D., 3μm) operating at 45°C and at a flow rate of 900μl/min. The method displays a linear relationship ranging from 20.0 to 5000ng/ml. Intra- and inter-day relative standard deviations are less than 5.7% and 7.0%, respectively and the accuracy ranged from 91.0 to 106.0%. The UHPLC-HESI-MS/MS analytical method we describe here is simple, sensitive, specific and capable of quantifying LY-354,740 in both rat and marmoset plasma, and is suitable to conduct PK studies after a single sub-cutaneous dose of 1.0mg/kg or lower in both species., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Study Objectives: REM sleep behavior disorder (RBD) is a parasomnia affecting 33% to 46% of patients with Parkinson's disease (PD). The existence of a unique and specific impaired cognitive profile in PD patients with RBD is still controversial. We extensively assessed cognitive functions to identify whether RBD is associated with more severe cognitive deficits in nondemented patients with PD., Methods: One hundred sixty-two participants, including 53 PD patients with RBD, 40 PD patients without RBD, and 69 healthy subjects, underwent polysomnography, a neurological assessment and an extensive neuropsychological exam to assess attention, executive functions, episodic learning and memory, visuospatial abilities, and language., Results: PD patients with RBD had poorer and clinically impaired performance in several cognitive tests compared to PD patients without RBD and healthy subjects. These two latter groups were similar on all cognitive measures. Mild cognitive impairment (MCI) diagnosis frequency was almost threefold higher in PD patients with RBD compared to PD patients without RBD (66% vs. 23%, p < .001). Moreover, subjective cognitive decline was reported in 89% of PD patients with RBD compared to 58% of PD patients without RBD (p = .024)., Conclusions: RBD in PD is associated with a more impaired cognitive profile and higher MCI diagnosis frequency, suggesting more severe and widespread neurodegeneration. This patient subgroup and their caregivers should receive targeted medical attention to better detect and monitor impairment and to enable the development of management interventions for cognitive decline and its consequences., (© Sleep Research Society 2017. Published by Oxford University Press on behalf of the Sleep Research Society. All rights reserved. For permissions, please e-mail journals.permissions@oup.com.)

Parkinson's disease (PD) has long been seen as a disorder caused by degeneration of the dopaminergic system, leading to the classic motor manifestations of the disease. However, there is now overwhelming evidence that PD is more than a disease merely caused by dopamine depletion. It is well-known that a myriad of other neurotransmitters are affected by the disease process. One such neurotransmitter is serotonin (5-HT). 5-HT has been shown to play a role in several motor and nonmotor manifestations of PD, including tremor, cognition, depression and psychosis. 5-HT also seems to play a critical role in L-3,4-dihydroxyphenylalanine (L-DOPA)-induced dyskinesia. A breadth of preclinical studies and clinical trials have been conducted that aimed at modulating the 5-HT system in order to alleviate depression, cognitive deficits, psychosis, and dyskinesia. In this Review, we summarize recent advances in the 5-HT field in PD, but with a translational emphasis. We start by presenting a novel nonhuman primate model of PD that presents with dual dopamine and 5-HT lesions. We then present preclinical and clinical data that introduce new concepts, such as the use of biased and partial agonists, as well as molecules recently introduced to the field of PD, such as eltoprazine, pimavanserin, nelotanserin, and SYN-120, to enhance therapeutic benefit while minimizing adverse events, notably on parkinsonian disability.

Background: Parkinson's disease (PD) psychosis is encountered in as many as 50% of patients with advanced disease. Treatment options for PD psychosis are few. In fact, only clozapine and pimavanserin have shown efficacy in randomised controlled trials. Clinicians are often reluctant to prescribe the former, due to the risk of agranulocytosis, while the latter is not widely available yet. Because it is already clinically available and exhibits high affinity for serotonin 2A receptors, a target with which both clozapine and pimavanserin interact, we hypothesised that the anti-depressant mirtazapine might be effective to alleviate PD psychosis., Methods: Here, we tested the anti-psychotic potential of mirtazapine in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-lesioned common marmoset. Five MPTP-lesioned marmosets exhibiting psychosis-like behaviours were administered L-3,4-dihydroxyphenylalanine (L-DOPA) in combination with mirtazapine (0.1, 1 and 10 mg/kg) or vehicle. We also tested the effect of mirtazapine on L-DOPA-induced dyskinesia., Results: The addition of mirtazapine 10 mg/kg to L-DOPA reduced psychosis-like behaviours by 50% (P < 0.05) and dyskinesia by 29% (P < 0.01), when compared to L-DOPA/vehicle. Importantly, the antipsychotic and antidyskinetic effects of mirtazapine were achieved without hindering L-DOPA anti-parkinsonian action., Conclusions: Our results suggest that mirtazapine may be effective to alleviate PD psychosis and, because the drug is clinically available, clinical trials that would assess its anti-psychotic efficacy in PD could be rapidly undertaken, hopefully leading to a new treatment option for this debilitating condition.

Introduction: Depressive symptoms are very common in patients with Parkinson's disease (PD) and have a significant impact on the quality of life., Methods: The present study analyzed the correlations between over-time changes in depressive symptoms and gray matter parameters of cortical thickness and subcortical volumes in non-demented PD patients., Results: A significant correlation was observed, between increased scores for depression over time and lower cortical thickness over time in the right temporo-parietal junction, right occipital medial region, right dorsolateral prefrontal cortex, right posterior cingulate region, left middle temporal as well as left supplementary motor area. Furthermore, the presence of depressive symptoms at baseline predicted increased cortical thinning over time in the left middle temporal, left anterior cingulate, right posterior cingulate and right parahippocampal cortices. Finally, a statistically significant negative correlation has been revealed between the thalamus' volume changes over time and the change in depressive symptoms scores. All other analyzed subcortical structures didn't reveal any significant correlations., Conclusion: These results suggest that depressive symptoms in PD patients are associated with gray matter cortical thinning and thalamus volume shrinkage over time and higher scores of depressive symptoms at baseline correlate with a higher rate of cortical thinning longitudinally. The present study highlights the importance of addressing depressive symptoms in PD patients early in the disease., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Introduction: Mutations in teneurin transmembrane protein 4 were reported to be a risk factor for essential tremor, but the relevance of this across different population remains to be examined. The aim of this study was to determine the frequency and spectrum of variations in teneurin transmembrane protein 4 in a cohort of Canadian essential tremor cases., Methods: The coding portion of teneurin transmembrane protein 4 was sequenced in 269 unrelated essential tremor cases and 288 matched control individuals using a targeted and high-throughput sequencing approach., Results: A total of 157 single nucleotide variations were identified, and from these 99 were a missense or nonsense mutation. A total of 68 cases were carriers of ≥1 rare missense or nonsense mutations, and 39 control individuals were carriers of the same types of variations. Gene-based association tests were used to jointly analyze the single nucleotide variations., Conclusions: Our results do not support a positive association between teneurin transmembrane protein 4 and the Canadian population. © 2017 International Parkinson and Movement Disorder Society., (© 2017 International Parkinson and Movement Disorder Society.)

Objectives: Aripiprazole is an antipsychotic that acts as a partial agonist at dopamine D2 receptors. Because of its partial agonist activity, it was believed that aripiprazole would be less susceptible than typical antipsychotics to induce extrapyramidal side effects. However, a few case-reports and case-series detailing aripiprazole-induced movement disorders have been published, suggesting that aripiprazole-induced movement disorders may arise. Here, we seek to report further cases of aripiprazole-induced movement disorders to raise the awareness of clinicians on this adverse effect., Methods: Patients referred to the André-Barbeau Movement Disorder clinic treated with aripiprazole were enrolled in this study. Their charts were retrospectively reviewed and data regarding past psychiatric history, past antipsychotic medication, duration of aripiprazole treatment, daily dose of aripiprazole administered, and resulting movement disorders were collected., Results: We report 14 cases of parkinsonism, tardive dyskinesia and akathisia induced by aripiprazole. Some of these, mostly the parkinsonian phenotype, abated spontaneously following drug discontinuation, whereas others, mostly related to tardive phenomena, persisted after aripiprazole was discontinued, and required treatment., Conclusions: This case-series adds to the existing literature that suggests that movement disorders may arise following treatment with aripiprazole. Clinicians should be aware of this potential side effect when prescribing aripiprazole to patients.

We conducted a genome-wide association study of essential tremor, a common movement disorder characterized mainly by a postural and kinetic tremor of the upper extremities. Twin and family history studies show a high heritability for essential tremor. The molecular genetic determinants of essential tremor are unknown. We included 2807 patients and 6441 controls of European descent in our two-stage genome-wide association study. The 59 most significantly disease-associated markers of the discovery stage were genotyped in the replication stage. After Bonferroni correction two markers, one (rs10937625) located in the serine/threonine kinase STK32B and one (rs17590046) in the transcriptional coactivator PPARGC1A were associated with essential tremor. Three markers (rs12764057, rs10822974, rs7903491) in the cell-adhesion molecule CTNNA3 were significant in the combined analysis of both stages. The expression of STK32B was increased in the cerebellar cortex of patients and expression quantitative trait loci database mining showed association between the protective minor allele of rs10937625 and reduced expression in cerebellar cortex. We found no expression differences related to disease status or marker genotype for the other two genes. Replication of two lead single nucleotide polymorphisms of previous small genome-wide association studies (rs3794087 in SLC1A2, rs9652490 in LINGO1) did not confirm the association with essential tremor., (© The Author (2016). Published by Oxford University Press on behalf of the Guarantors of Brain.)

Dementia affects a high proportion of Parkinson's disease (PD) patients and poses a burden on caregivers and healthcare services. Electroencephalography (EEG) is a common nonevasive and nonexpensive technique that can easily be used in clinical settings to identify brain functional abnormalities. Only few studies had identified EEG abnormalities that can predict PD patients at higher risk for dementia. Brain connectivity EEG measures, such as multiscale entropy (MSE) and phase-locking value (PLV) analyses, may be more informative and sensitive to brain alterations leading to dementia than previously used methods. This study followed 62 dementia-free PD patients for a mean of 3.4 years to identify cerebral alterations that are associated with dementia. Baseline resting state EEG of patients who developed dementia (N = 18) was compared to those of patients who remained dementia-free (N = 44) and of 37 healthy subjects. MSE and PLV analyses were performed. Partial least squares statistical analysis revealed group differences associated with the development of dementia. Patients who developed dementia showed higher signal complexity and lower PLVs in low frequencies (mainly in delta frequency) than patients who remained dementia-free and controls. Conversely, both patient groups showed lower signal variability and higher PLVs in high frequencies (mainly in gamma frequency) compared to controls, with the strongest effect in patients who developed dementia. These findings suggest that specific disruptions of brain communication can be measured before PD patients develop dementia, providing a new potential marker to identify patients at highest risk of developing dementia and who are the best candidates for neuroprotective trials.

In Parkinson's disease, electroencephalographic abnormalities during wakefulness and non-rapid eye movement sleep (spindles) were found to be predictive biomarkers of dementia. Because rapid eye movement sleep is regulated by the cholinergic system, which shows early degeneration in Parkinson's disease with cognitive impairment, anomalies during this sleep stage might mirror dementia development. In this prospective study, we examined baseline electroencephalographic absolute spectral power across three states of consciousness (non-rapid eye movement sleep, rapid eye movement sleep, and wakefulness) in 68 non-demented patients with Parkinson's disease and 44 healthy controls. All participants underwent baseline polysomnographic recordings and a comprehensive neuropsychological assessment. Power spectral analyses were performed on standard frequency bands. Dominant occipital frequency during wakefulness and ratios of slow-to-fast frequencies during rapid eye movement sleep and wakefulness were also computed. At follow-up (an average 4.5 years after baseline), 18 patients with Parkinson's disease had developed dementia and 50 patients remained dementia-free. In rapid eye movement sleep, patients with Parkinson's disease who later developed dementia showed, at baseline, higher absolute power in delta and theta bands and a higher slowing ratio, especially in temporal, parietal, and occipital regions, compared to patients who remained dementia-free and controls. In non-rapid eye movement sleep, lower baseline sigma power in parietal cortical regions also predicted development of dementia. During wakefulness, patients with Parkinson's disease who later developed dementia showed lower dominant occipital frequency as well as higher delta and slowing ratio compared to patients who remained dementia-free and controls. At baseline, higher slowing ratios in temporo-occipital regions during rapid eye movement sleep were associated with poor performance on visuospatial tests in patients with Parkinson's disease. Using receiver operating characteristic curves, we found that best predictors of dementia in Parkinson's disease were rapid eye movement sleep slowing ratios in posterior regions, wakefulness slowing ratios in temporal areas, and lower dominant occipital frequency. These results suggest that electroencephalographic slowing during sleep is a new promising predictive biomarker for Parkinson's disease dementia, perhaps as a marker of cholinergic denervation., (© The Author (2016). Published by Oxford University Press on behalf of the Guarantors of Brain. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Sleep disturbances and cognitive impairment are common non-motor manifestations of Parkinson's disease (PD). Recent studies suggest that sleep spindles and slow waves play a role in brain plasticity mechanisms and are associated with cognitive performance. However, it remains unknown whether these sleep parameters could serve as markers of cognitive decline in PD. Therefore, we examined whether alterations in sleep spindles and slow waves at baseline visit were associated with increased likelihood of developing dementia at follow-up in PD. Sixty-eight nondemented PD patients (64.9 ± 8.8 years old; 46 men) participated in the study, along with 47 healthy individuals (65.0 ± 10.6 years old; 30 men). All participants underwent baseline polysomnographic recording and a comprehensive neuropsychological assessment. Sleep spindles (12-15 Hz) and slow waves (>75 μV and <4 Hz) were automatically detected on all-night non-rapid eye movement sleep electroencephalography. At follow-up (mean: 4.5 years later), 18 PD patients developed dementia (70.2 ± 7.6 years old; 13 men) and 50 remained dementia-free (63.0 ± 8.5 years old; 33 men). Sleep spindle density and amplitude were lower in PD patients who converted to dementia compared with both patients who remained dementia-free and controls, mostly in posterior cortical regions (p < 0.05). Dementia-free PD patients were intermediate between dementia patients and controls, with lower baseline sleep spindle density in all cortical areas compared with controls (p < 0.01). In demented PD patients, lower sleep spindle amplitude in parietal and occipital areas was associated with poorer visuospatial abilities. Although slow wave amplitude was lower in PD patients compared with controls (p < 0.0001), no difference was observed between those who developed or did not develop dementia. Results demonstrate non-rapid eye movement sleep electroencephalographic abnormalities in PD patients. Sleep spindle activity was particularly impaired in PD patients who developed dementia, with a more posterior topographic pattern. Sleep spindle alterations are associated with later development of dementia in PD, and thus may serve as an additional marker of cognitive decline in these patients., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Background: Parkinson's disease is characterized by numerous non-motor symptoms, including sleep disorders. Sleep apnea has been reported in a substantial proportion of patients with Parkinson's disease, but it is unclear whether it has significant consequences for the quality of life of those affected or whether it is associated with other manifestations of the disease., Objective: To verify whether sleep apnea is associated with more severe motor and non-motor clinical features in Parkinson's disease., Methods: Parkinson's disease patients underwent polysomnography to diagnose the presence of sleep apnea (apnea-hypopnoea index >10). Participants also underwent an extensive assessment, blinded to sleep apnea status, to determine disease severity, quantitative motor indices, motor subtypes, treatment complications, and sleep, autonomic, psychiatric, and sensory dysfunctions. Cognitive status was also determined with a complete neuropsychological assessment. Results were assessed using regression analysis adjusted for age, sex, and disease duration., Results: Of 92 patients examined, 19 had sleep apnea (21%) and 73 did not. We found no significant differences in motor and non-motor symptoms or signs between apneic and non-apneic Parkinson's disease patients. The use of different apnea-hypopnoea index cut-offs (>5 and >15) produced similar results., Conclusions: Our results show that sleep apnea is not associated with more severe motor or non-motor manifestations in Parkinson's disease. More studies including control groups are needed to confirm the implications of those results.

Background: Maintaining a physically active lifestyle promotes general health. Recent studies have demonstrated that patients with Parkinson's disease (PD) fail to meet the suggested levels of physical activity and that targeted interventions do not always improve this behavior. One validated treatment for motor symptoms in PD is subthalamic stimulation (STN DBS)., Objective: Assess whether motor symptom improvement following STN DBS translated into increased physical activity behavior., Methods: Twenty patients with PD scheduled for bilateral STN DBS filled-out the Phone-FITT physical activity questionnaire and the SF-36 quality of life questionnaire prior to surgery and 6 to 9 months postoperatively. Data were compared to age- and gender-matched healthy controls., Results: Our results demonstrate that PD patients' quality of life is significantly lower than healthy controls. While STN DBS improves motor symptoms in the intermediate term, it only improves some aspects of quality of life related to physical function. Furthermore, STN DBS does not modify physical activity behavior measured by the Phone-FITT, whether for household or recreational activities., Conclusion: The current study demonstrates that the motor improvements observed after STN DBS do not lead to systematic improvements in all aspects of quality of life or increased levels of physical activity. This highlights the need to develop and implement intervention strategies to promote an active lifestyle in this population, even if clinical improvement is evident following surgery.

Introduction: Depressive symptoms are very common in patients with Parkinson's disease (PD) and have a significant impact on the quality of life. Dopaminergic medication has been shown to have an influence on the development of depressive symptoms., Materials and Methods: The present study analyzed two groups of non-demented patients with PD, with and without depressive symptoms, and reported the correlations between antiparkinsonian medication [specifically levodopa (l-DOPA) and dopaminergic agonists] with depressive symptoms., Results: A strong statistically significant positive correlation between l-DOPA dosages and the level of depressive symptoms has been revealed, suggesting that higher l-DOPA dosages correlate with a worsening of depressive status. No significant correlation was found with dopamine agonists., Discussion: The results of this study show that in patients with PD, higher l-DOPA dosages correlate with worse depressive symptoms. From this point of view, PD patients need to be better diagnosed with respect to depressive symptoms and need additional treatment adjustment when clinical manifestations of depression are present. Clinicians must be aware that dopaminergic drugs are not sufficient to alleviate depressive symptoms.

Background: Cases with essential tremor (ET) have been described with Lewy body inclusions, the hallmark of Parkinson disease (PD). Patients with PD may suffer from anosmia, depression, constipation, and rapid eye movement sleep behavior disorder (RBD), sometimes years before the appearance of their motor syndrome. The objective of this study was to evaluate the prevalence of these non-motor Parkinson's associated symptoms in patients with ET., Methods: Fifty ET subjects were contacted by phone and given questionnaires evaluating the presence or absence of anosmia, depression, constipation, and RBD. Frequencies of these symptoms were compared with their published prevalence in the general population., Results: Of the patients with ET, 4.5% reported having anosmia or hyposmia and 21.7% reported being constipated, similar to what is observed in the general population. Using a screening questionnaire for RBD, 43.5% of ET patients are possibly suffering from RBD, whereas in the general population prevalence is estimated to be 0.5%. Finally, depression was detected in 21.7% of ET patients; in the general population, prevalence is 5%., Discussion: Patients with ET seem to have more RBD and more depression than found in the general population. Prospective studies with normal control groups are needed to confirm these findings.

Background: Autosomal recessive spastic ataxia of Charlevoix-Saguenay (ARSACS) is an increasingly recognized form of spastic ataxia worldwide, but early diagnosis remains a challenge., Methods: We reviewed the initial presentation (n = 40) and early clinical evolution (n = 50) of a large ARSACS cohort that was followed at the Saguenay Neuromuscular clinic., Results: The average age at presentation was 3.41 ± 1.55 years. Increased deep tendon reflexes were more common than spasticity initially, and the neuropathy only became apparent clinically in the second decade. Despite a homogeneous genetic background, some patients showed no signs of neuropathy or spasticity by the age of 18 years., Conclusions: At presentation, ARSACS lacks certain features that are considered typical in adults after years of evolution. Considering that ARSACS is probably under-diagnosed, it should be included in the differential diagnosis of early onset ataxias with or without pyramidal features and is worthwhile to consider in older patients, even when some features are absent., (© 2013 Movement Disorder Society.)

Dystonia is a syndrome of sustained muscular contractions with numerous underlying etiologies. This review examines the varied phenomenology of dystonias, its evolving classification including recent genetic data as well as its clinical investigation and treatment. Although age of onset, anatomical distribution and family history are key elements of the investigation of dystonia, classification increasingly relies on etiologic and genetic criteria. Physiological abnormalities in striato-cortical circuits are common in dystonia but the pathophysiology is still unclear. In recent years, a great deal has been learned on the more common primary dystonias such as primary torsion dystonia and on dystonia-plus syndromes such as dopamine responsive dystonia. Treatment of dystonia has also evolved and there are now a number of therapeutic agents with clear beneficial effects including anticholinergics, benzodiazepines, and botulinum toxin and there is growing interest in neurofunctional surgery including deep brain stimulation.

Cognitive deficits affecting executive (frontal) functions have been widely described in Parkinson's disease (PD). However, dopa therapies are generally ineffective at reversing these deficits, except for tasks involving a sharing of attention such as working memory or simultaneous processing tasks. The aim of this study was to assess the relation between the nigrostriatal dopaminergic denervation in PD, as measured by SPECT with (123)Iodine-beta-CIT and the cognitive deficits, as measured by a simultaneous processing task, which had already been shown to be sensitive to dopa treatment. Ten patients with PD and ten control subjects were selected and matched for age, sex, and education. All subjects were assessed using computed visuo-auditory tasks which allow for the measurement of three cognitive processing conditions: 1) a Selective Processing Time; 2) a Competitive Processing Time; and 3) a Simultaneous Processing Time. Patients with PD were assessed both with (ON) and without (OFF) their usual dopaminergic treatment. The simultaneous processing condition but not the selective or the competitive conditions took significantly more time for patients with PD OFF than for either the control subjects or the patients with PD ON. In addition, when patients with PD were OFF, the simultaneous processing condition was correlated with the (123)Iodine-beta-CIT binding, but not when they were ON. These results suggest that nigrostriatal DA denervation may be involved in the specific impairment that patients with PD experience with simultaneous cognitive processing.