Rating Scales for Motor Symptoms and Signs in Huntington's Disease: Critique and Recommendations

Profiling deutetrabenazine extended-release tablets for tardive dyskinesia and chorea associated with Huntington's disease

INTRODUCTION

Tardive dyskinesia (TD) and Huntington's disease (HD)-associated chorea are persistent and disabling hyperkinetic disorders that can be treated with vesicular monoamine transporter type 2 (VMAT2) inhibitors, including the recently approved once-daily (QD) formulation of deutetrabenazine (DTBZ ER). While its efficacy and safety profile have not been directly investigated, currently available data confirms bioequivalence and similar bioavailability to the twice-daily formulation (DTBZ BID).

AREAS COVERED

The authors briefly review the pivotal trials establishing efficacy of DTBZ for TD and HD-associated chorea, the pharmacokinetic data for bioequivalence between QD and BID dosing of DTBZ, as well as dose proportionality evidence, titration recommendations, and safety profile for DTBZ ER.

EXPERT OPINION

Long-term data show that DTBZ is efficacious and well tolerated for the treatment of TD and HD-associated chorea. DTBZ ER likely demonstrates therapeutic equivalence with no new safety signals. Due to the lack of comparative clinical trial data, no evidence-based recommendation about choice of VMAT2 inhibitor or switching between VMAT2 inhibitors can be made about best practice. Ultimately, QD dosing may offer the chance of improved medication adherence, an important consideration in patients with complex treatment regimens and/or patients with cognitive decline.

Comparing balance using the BESTest in Alzheimer, Huntington and Parkinson disease

Aim: Individuals with Alzheimer disease (AD), Huntington disease (HD) and Parkinson disease (PD) have impaired balance, and comparing these deficits could improve management of neurological diseases.Methods: Scores on the Balance Evaluation Systems Test (BESTest) were compared across three groups, consisting of individuals with AD, HD and PD in early stages of their respective disease.Results: Individuals with PD had significantly higher scores on the BESTest than individuals with AD (95% CI [4.30, 21.37], p < 0.01) or HD (95% CI [6.53, 24.18], p < 0.001). Individuals with AD and HD were not significantly different on the overall BESTest or any of its subsections.Conclusion: AD and HD may have overlapping pathologies resulting in early and similar balance impairments in these groups.

Time to Functional Loss as an Endpoint in Huntington's Disease Trials: Enrichment and Sample Size

BACKGROUND

Clinical trial scenarios can be modeled using data from observational studies, providing critical information for design of real-world trials. The Huntington's Disease Integrated Staging System (HD-ISS) characterizes disease progression over an individual's lifespan and allows for flexibility in the design of trials with the goal of delaying progression. Enrichment methods can be applied to the HD-ISS to identify subgroups requiring smaller estimated sample sizes.

OBJECTIVE

Investigate time to the event of functional decline (HD-ISS Stage 3) as an endpoint for trials in HD and present sample size estimates after enrichment.

METHODS

We classified individuals from observational studies according to the HD-ISS. We assessed the ability of the prognostic index normed (PIN) and its components to predict time to HD-ISS Stage 3. For enrichment, we formed groups from deciles of the baseline PIN distribution for HD-ISS Stage 2 participants. We selected enrichment subgroups closer to Stage 3 transition and estimated sample sizes, using delay in the transition time as the effect size.

RESULTS

In predicting time to HD-ISS Stage 3, PIN outperforms its components. Survival curves for each PIN decile show that groups with PIN from 1.48 to 2.74 have median time to Stage 3 of approximately 2 years and these are combined to create enrichment subgroups. Sample size estimates are presented by enrichment subgroup.

CONCLUSIONS

PIN is predictive of functional decline. A delay of 9 months or more in the transition to Stage 3 for an enriched sample yields feasible sample size estimates, demonstrating that this approach can aid in planning future trials. © 2024 The Author(s). Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Neurosurgical therapy possibilities in treatment of Huntington disease: An update

INTRODUCTION

Huntington's disease (HD) is a hereditary condition caused by the expansion of the CAG trinucleotide in the huntingtin gene on chromosome 4, resulting in motor, cognitive, and psychiatric disorders that significantly impact patients' quality of life. Despite the lack of effective treatments for the disease, various surgical strategies have been explored to alleviate symptoms and slow its progression.

METHODOLOGY

A comprehensive systematic literature review was conducted, including MeSH terms, yielding only 38 articles that were categorized based on the surgical procedure. The study aimed to describe the types of surgeries performed and their efficacy in HD patients.

RESULTS

Deep brain stimulation (DBS) involved 41 predominantly male patients with bilateral implantation in the globus pallidus, showing a preoperative Unified Huntington's Disease Rating Scale (UHDRS) score of 60.25 ± 16.13 and a marked postoperative value of 48.54 ± 13.93 with a p < 0.018 at one year and p < 0.040 at three years. Patients experienced improvement in hyperkinesia but worsening of bradykinesia. Additionally, cell transplantation in 119 patients resulted in a lower preoperative UHDRS score of 34.61 ± 14.61 and a significant postoperative difference of 32.93 ± 15.87 (p < 0.016), respectively, in the first to third years of following. Some now, less used procedures were crucial for understanding brain function, such as pallidotomies in 3 patients, showing only a 25 % difference from their baseline.

CONCLUSION

Despite advancements in technology, there is still no curative treatment, only palliative options. Promising treatments like trophic factor implantation offer new prospects for the future.

Epidemiology of Huntington's Disease in Latin America: A Systematic Review and Meta-Analysis

BACKGROUND

Latin America has played a crucial role in advancing our understanding of Huntington's disease (HD). However, previous global reviews include limited data from Latin America. It is possible that English-based medical search engines may not capture all the relevant studies.

METHODS

We searched databases in Spanish, Portuguese, and English. The names of every country in Latin America in English-based search engines were used to ensure we found any study that had molecular ascertainment and provided general epidemiological information or subpopulation data. Additionally, we contacted experts across the region.

RESULTS

The search strategy yielded 791 citations; 24 studies met inclusion criteria, representing 12 of 36 countries. The overall pooled prevalence was 0.64 per 100,000 (prediction interval, 0.06-7.22); for cluster regions, it was 54 per 100,000 (95% CI, 34.79-84.92); for juvenile HD, it was 8.7% (prediction interval, 5.12-14.35), and 5.9% (prediction interval, 2.72-13.42) for late-onset HD. The prevalence was higher for Mexico, Peru, and Brazil. However, there were no significant differences between Central America and the Caribbean versus South America.

CONCLUSION

The prevalence of HD appears to be similar across Latin America. However, we infer that our findings are underestimates, in part because of limited research and underdiagnosis of HD because of limited access to molecular testing and the availability of neurologists and movement disorders specialists. Future research should focus on identifying pathways to improve access to molecular testing and education and understanding differences among different ancestral groups in Latin America. © 2024 International Parkinson and Movement Disorder Society.

Identification and Assessment of Outcome Measurement Instruments in Cauda Equina Syndrome: A Systematic Review

STUDY DESIGN

This was a systematic review of surgically managed Cauda Equina Syndrome (CES) Outcome Measurement Instruments (OMI).

OBJECTIVE

A core outcome set (COS) defines agreed outcomes which should be reported as a minimum in any research study for a specific condition. This study identified OMIs used in the wider CES literature and compare these to the established CESCOS.

METHODS

To identify measurement methods and instruments in the CES surgical outcome evidence base, a systematic review was performed. Medline, Embase and CINAHL plus databases were queried. In addition, a secondary search for validation studies of measurement instruments in CES was undertaken. Identified studies from this search were subject to the COSMIN risk of bias assessment.

RESULTS

In total, 112 studies were identified investigating surgical outcomes for CES. The majority (80%, n = 90) of these OMI studies were retrospective in nature and only 55% (n = 62) utilised a measurement method or instrument. The remaining 50 studies used study specific definitions for surgical outcomes defined within their methods. Of the 59 measurement instruments identified, 60% (n = 38 instruments) were patient reported outcome measures. Only one validated instrument was identified, which was a patient reported outcome measure. The validated instrument was not used in any study identified in the initial search (to identify measurement instruments).

CONCLUSIONS

This review highlights the wide heterogeneity of measurement instruments used in surgically managed CES research. Subsequently, there is need for consensus agreement on which instrument or instruments should be used to measure each core outcome for CES surgical outcomes.

Estimation of Gait Parameters in Huntington's Disease Using Wearable Sensors in the Clinic and Free-living Conditions

In Huntington's disease (HD), wearable inertial sensors could capture subtle changes in motor function. However, disease-specific validation of methods is necessary. This study presents an algorithm for walking bout and gait event detection in HD using a leg-worn accelerometer, validated only in the clinic and deployed in free-living conditions. Seventeen HD participants wore shank- and thigh-worn tri-axial accelerometers, and a wrist-worn device during two-minute walk tests in the clinic, with video reference data for validation. Thirteen participants wore one of the thigh-worn tri-axial accelerometers (AP: ActivPAL4) and the wrist-worn device for 7 days under free-living conditions, with proprietary AP data used as reference. Gait events were detected from shank and thigh acceleration using the Teager-Kaiser energy operator combined with unsupervised clustering. Estimated step count (SC) and temporal gait parameters were compared with reference data. In the clinic, low mean absolute percentage errors were observed for stride (shank/thigh: 0.6/0.9%) and stance (shank/thigh: 3.3/7.1%) times, and SC (shank/thigh: 3.1%). Similar errors were observed for proprietary AP SC (3.2%), with higher errors observed for the wrist-worn device (10.9%). At home, excellent agreement was observed between the proposed algorithm and AP software for SC and time spent walking (ICC [Formula: see text]). The wrist-worn device overestimated SC by 34.2%. The presented algorithm additionally allowed stride and stance time estimation, whose variability correlated significantly with clinical motor scores. The results demonstrate a new method for accurate estimation of HD gait parameters in the clinic and free-living conditions, using a single accelerometer worn on either the thigh or shank.

Unraveling progression subtypes in people with Huntington's disease

Background

Huntington's disease (HD) is a progressive neurodegenerative disease caused by a CAG trinucleotide expansion in the huntingtin gene. The length of the CAG repeat is inversely correlated with disease onset. HD is characterized by hyperkinetic movement disorder, psychiatric symptoms, and cognitive deficits, which greatly impact patient's quality of life. Despite this clear genetic course, high variability of HD patients' symptoms can be observed. Current clinical diagnosis of HD solely relies on the presence of motor signs, disregarding the other important aspects of the disease. By incorporating a broader approach that encompasses motor as well as non-motor aspects of HD, predictive, preventive, and personalized (3P) medicine can enhance diagnostic accuracy and improve patient care.

Methods

Multisymptom disease trajectories of HD patients collected from the Enroll-HD study were first aligned on a common disease timescale to account for heterogeneity in disease symptom onset and diagnosis. Following this, the aligned disease trajectories were clustered using the previously published Variational Deep Embedding with Recurrence (VaDER) algorithm and resulting progression subtypes were clinically characterized. Lastly, an AI/ML model was learned to predict the progression subtype from only first visit data or with data from additional follow-up visits.

Results

Results demonstrate two distinct subtypes, one large cluster (n = 7122) showing a relative stable disease progression and a second, smaller cluster (n = 411) showing a dramatically more progressive disease trajectory. Clinical characterization of the two subtypes correlates with CAG repeat length, as well as several neurobehavioral, psychiatric, and cognitive scores. In fact, cognitive impairment was found to be the major difference between the two subtypes. Additionally, a prognostic model shows the ability to predict HD subtypes from patients' first visit only.

Conclusion

In summary, this study aims towards the paradigm shift from reactive to preventive and personalized medicine by showing that non-motor symptoms are of vital importance for predicting and categorizing each patients' disease progression pattern, as cognitive decline is oftentimes more reflective of HD progression than its motor aspects. Considering these aspects while counseling and therapy definition will personalize each individuals' treatment. The ability to provide patients with an objective assessment of their disease progression and thus a perspective for their life with HD is the key to improving their quality of life. By conducting additional analysis on biological data from both subtypes, it is possible to gain a deeper understanding of these subtypes and uncover the underlying biological factors of the disease. This greatly aligns with the goal of shifting towards 3P medicine.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13167-024-00368-2.

Neuroimaging biomarkers in Huntington's disease: Preparing for a new era of therapeutic development

BACKGROUND

A critical challenge for Huntington's disease (HD) clinical trials in disease modification is the definition of endpoints that can capture change when clinical signs are subtle/non-existent. Reliable biomarkers are therefore urgently needed to facilitate drug development by allowing the enrichment of clinical trial populations and providing measures of benefit that can support the establishment of efficacy.

METHODS

By systematically examining the published literature on HD neuroimaging biomarker studies, we sought to advance knowledge to guide the validation of neuroimaging biomarkers. We started by reviewing both cross-sectional and longitudinal studies and then conducted an in-depth review to make quantitative comparisons between biomarkers using data only from longitudinal studies with samples sizes larger than ten participants in PET studies or 30 participants in MRI studies.

RESULTS

From a total of 2202 publications initially identified, we included 32 studies, 19 of which underwent in-depth comparative review. The majority of included studies used various MRI-based methods (manual to automatic) to longitudinally assess either the volume of the putamen or the caudate, which have been shown to undergo significant structural change during HD natural history.

CONCLUSION

Despite the impressively large number of neuroimaging biomarker studies, only a small number of adequately designed studies met our criteria. Among these various biomarkers, MRI-based volumetric analyses of the caudate and putamen are currently the best validated for use in the disease phase before clinical motor diagnosis. A biomarker that can be used to demonstrate a disease-modifying effect is still missing.

Defining Clinical Meaningfulness in Huntington's Disease

BACKGROUND

Minimal clinically important difference (MCID) represents the smallest within-person change on an outcome measure considered meaningful to the patient. Anchor-based MCID methods evaluate the relationship between changes in an outcome measure and the patient-reported clinical importance of that change.

OBJECTIVE

This study aims to estimate longitudinal MCID for clinically relevant outcome measures for individuals who have Stages 2 or 3 disease as measured by the Huntington's Disease Integrated Staging System (HD-ISS).

METHODS

Data were drawn from Enroll-HD, a large global longitudinal, observational study and clinical research platform for HD family members. We analyzed HD participants (N = 11,070) by staging group using time frames ranging from 12 to 36 months. The anchor was the physical component summary score of the 12-item short-form health survey. HD-relevant motor, cognitive, and functional outcome measures were independent, external criterion outcomes. Complex analysis was conducted using multiple, independent, linear mixed effect regression models with decomposition to calculate MCID for each external criterion by group.

RESULTS

MCID estimates varied by progression stage. MCID estimates increased as stage progression increased and as the time frame increased. MCID values for key HD measures are provided. For example, starting in HD-ISS stage 2, meaningful group change over 24 months equals an average increase of 3.6 or more points on the Unified Huntington's Disease Rating Scale Total Motor Score.

CONCLUSIONS

This is the first study to examine MCID estimation thresholds for HD. The results can be used to improve clinical interpretation of study outcomes and enable treatment recommendations to support clinical decision-making and clinical trial methodology. © 2023 International Parkinson and Movement Disorder Society.

Home-Based Exercise to Improve Motor Functions, Cognitive Functions, and Quality of Life in People with Huntington's Disease: A Systematic Review and Meta-Analysis

Exercise in different settings has become a fundamental part of Huntington's disease (HD) management. The aim of this systematic review and meta-analysis was to investigate the effectiveness of home-based exercises (HBE) in HD. Randomized controlled trials (RCTs) investigating the effect of HBE on motor, cognitive, or health-related quality of life (QoL) outcomes in HD were included. Standardized mean difference (SMD), the 95% confidence interval, and p-values were calculated by comparing the outcomes change between HBE and control groups. Seven RCTs met the inclusion criteria. The included RCTs prescribed different types of HBEs, i.e., aerobic strengthening, walking, balance, and fine motor exercises. The HBE protocol length was between 6 and 36 weeks. The meta-analyses showed a significant effect of HBE intervention on motor function measure by Unified Huntington Disease Rating and overall QoL measure by Short Form-36 post-treatment respectively, [SMD = 0.481, p = 0.048], [SMD = 0.378, p = 0.003]. The pooled analysis did not detect significant changes in cognition, gait characteristics, or functional balance scales. The current study shows the positive effect of HBE in HD, especially on motor function and QoL. No significant adverse events were reported. The current results support the clinical effect of HBE intervention on motor function and QoL in HD patients. However, these results should be taken with caution due to the limited available evidence. Well-designed clinical studies that consider the disease severity and stages are required in the future.

Safety and Feasibility of Research Lumbar Puncture in Huntington's Disease: The HDClarity Cohort and Bioresource

BACKGROUND

Biomarkers are needed to monitor disease progression, target engagement and efficacy in Huntington's disease (HD). Cerebrospinal fluid (CSF) is an ideal medium to research such biomarkers due to its proximity to the brain.

OBJECTIVE

To investigate the safety and feasibility of research lumbar punctures (LP) in HD.

METHODS

HDClarity is an ongoing international biofluid collection initiative built on the Enroll-HD platform, where clinical assessments are recorded. It aims to recruit 1,200 participants. Biosamples are collected following an overnight fast: blood via venipuncture and CSF via LP. Participants are healthy controls and HD gene expansion carriers across the disease spectrum. We report on monitored data from February 2016 to September 2019.

RESULTS

Of 448 participants screened, 398 underwent at least 1 sampling visit, of which 98.24% were successful (i.e., CSF was collected), amounting to 10,610 mL of CSF and 8,200 mL of plasma. In the total 572 sampling visits, adverse events were reported in 24.13%, and headaches of any kind and post-LP headaches in 14.86% and 12.24%, respectively. Frequencies were less in manifest HD; gender, age, body mass index and disease burden score were not associated with the occurrence of the events in gene expansion carriers. Headaches and back pain were the most frequent adverse events.

CONCLUSION

HDClarity is the largest CSF collection initiative to support scientific research into HD and is now stablished as a leading resource for HD research. Our data confirm that research LP in HD are feasible and acceptable to the community, and have a manageable safety profile.

Predicting Severity of Huntington's Disease With Wearable Sensors

The Unified Huntington's Disease Rating Scale (UHDRS) is the primary clinical assessment tool for rating motor function in patients with Huntington's disease (HD). However, the UHDRS and similar rating scales (e.g., UPDRS) are both subjective and limited to in-office assessments that must be administered by a trained and experienced rater. An objective, automated method of quantifying disease severity would facilitate superior patient care and could be used to better track severity over time. We conducted the present study to evaluate the feasibility of using wearable sensors, coupled with machine learning algorithms, to rate motor function in patients with HD. Fourteen participants with symptomatic HD and 14 healthy controls participated in the study. Each participant wore five adhesive biometric sensors applied to the trunk and each limb while completing brief walking, sitting, and standing tasks during a single office visit. A two-stage machine learning method was employed to classify participants by HD status and to predict UHDRS motor subscores. Linear discriminant analysis correctly classified all participants' HD status except for one control subject with abnormal gait (96.4% accuracy, 92.9% sensitivity, and 100% specificity in leave-one-out cross-validation). Two regression models accurately predicted individual UHDRS subscores for gait, and dystonia within a 10% margin of error. Our regression models also predicted a composite UHDRS score-a sum of left and right arm rigidity, total chorea, total dystonia, bradykinesia, gait, and tandem gait subscores-with an average error below 15%. Machine learning classifiers trained on brief in-office datasets discriminated between controls and participants with HD, and could accurately predict selected motor UHDRS subscores. Our results could enable the future use of biosensors for objective HD assessment in the clinic or remotely and could inform future studies for the use of this technology as a potential endpoint in clinical trials.

Considerations for clinical trial design and conduct in the evaluation of novel advanced therapeutics in neurodegenerative disease

The recent advances in the development of potentially disease modifying cell and gene therapies for neurodegenerative disease has resulted in the production of a number of promising novel therapies which are now moving forward to clinical evaluation. The robust evaluation of these therapies pose a significant number of challenges when compared to more traditional evaluations of pharmacotherapy, which is the current mainstay of neurodegenerative disease symptom management. Indeed, there is an inherent complexity in the design and conduct of these trials at multiple levels. Here we discuss specific aspects requiring consideration in the context of investigating novel cell and gene therapies for neurodegenerative disease. This extends to overarching trial designs that could be employed and the factors that underpin design choices such outcome assessments, participant selection and methods for delivery of cell and gene therapies. We explore methods of data collection that may improve efficiency in trials of cell and gene therapy to maximize data sharing and collaboration. Lastly, we explore some of the additional context beyond efficacy evaluations that should be considered to ensure implementation across relevant healthcare settings.

Innovative Therapeutic Approaches for Huntington's Disease: From Nucleic Acids to GPCR-Targeting Small Molecules

Huntington’s disease (HD) is a fatal neurodegenerative disorder due to an extraordinarily expanded CAG repeat in the huntingtin gene that confers a gain-of-toxic function in the mutant protein. There is currently no effective cure that attenuates progression and severity of the disease. Since HD is an inherited monogenic disorder, lowering the mutant huntingtin (mHTT) represents a promising therapeutic strategy. Huntingtin lowering strategies mostly focus on nucleic acid approaches, such as small interfering RNAs (siRNAs) and antisense oligonucleotides (ASOs). While these approaches seem to be effective, the drug delivery to the brain poses a great challenge and requires direct injection into the central nervous system (CNS) that results in substantial burden for patients. This review discusses the topics on Huntingtin lowering strategies with clinical trials in patients already underway and introduce an innovative approach that has the potential to deter the disease progression through the inhibition of GPR52, a striatal-enriched class A orphan G protein-coupled receptor (GPCR) that represents a promising therapeutic target for psychiatric disorders. Chemically simple, potent, and selective GPR52 antagonists have been discovered through high-throughput screening and subsequent structure-activity relationship studies. These small molecule antagonists not only diminish both soluble and aggregated mHTT in the striatum, but also ameliorate HD-like defects in HD mice. This therapeutic approach offers great promise as a novel strategy for HD therapy, while nucleic acid delivery still faces considerable challenges.

Neurobiological and Psychosocial Correlates of Communication Between Huntington's Disease Patients and Their Offspring

OBJECTIVE

Huntington's disease (HD) is an autosomal dominant neurodegenerative disease that presents significant challenges to family communication. The investigators examined observations of communication between parents with HD and their offspring talking about the challenges of HD and explored potential correlates of their communication.

METHODS

The sample included parents with HD and their adolescent and young-adult offspring (N=64). Parent communication and chorea were independently coded from video recordings. Parents and offspring completed working memory assessments and self-reports of neuropsychiatric symptoms, stress, and coping.

RESULTS

Evidence was found for the association of observed parent-offspring communication with disease markers, psychosocial characteristics, and neurocognitive function. For parents, disease markers and working memory were correlates of communication, whereas offspring's psychiatric symptoms, stress, and coping were associated with their communication.

CONCLUSIONS

These findings have potential implications for clinical interventions to enhance communication and quality of life for HD families.

State-of-the-art pharmacological approaches to reduce chorea in Huntington's disease

Introduction Chorea is a common motor manifestation of Huntington's disease (HD). Two vesicular monoamine transporter type 2 (VMAT-2) inhibitors have been approved by the FDA for treatment of HD chorea, and a third is currently being assessed in a phase 3 trial. Antipsychotic therapies are used off-label for treatment of chorea and can treat comorbid psychiatric symptoms. There is considerable clinical equipoise regarding the safe and effective treatment of chorea and comorbid symptoms in HD.Areas covered: The authors review existing medications used to treat HD chorea in the United States of America (USA). Implications for common comorbid symptoms (e.g. psychiatric, metabolic) are also discussed. Available therapies vary widely in cost, dosing frequency, and off -target effects, both beneficial or negative.Expert opinion: Treatment considerations for chorea should account for patient comorbidities. The authors recommend prospective, observational clinical effectiveness studies which can evaluate the long-term comparative effectiveness and safety of VMAT-2 inhibitors and antipsychotics in HD. Data regarding safety of dual therapy is another critical need. This is especially timely given the changing landscape of HD therapies which may increase cost burden and possibly extend both asymptomatic and symptomatic years for HD patients.

Objectively characterizing Huntington's disease using a novel upper limb dexterity test

BACKGROUND

The Clinch Token Transfer Test (C3t) is a bi-manual coin transfer task that incorporates cognitive tasks to add complexity. This study explored the concurrent and convergent validity of the C3t as a simple, objective assessment of impairment that is reflective of disease severity in Huntington's, that is not reliant on clinical expertise for administration.

METHODS

One-hundred-and-five participants presenting with pre-manifest (n = 16) or manifest (TFC-Stage-1 n = 39; TFC-Stage-2 n = 43; TFC-Stage-3 n = 7) Huntington's disease completed the Unified Huntington's Disease Rating Scale and the C3t at baseline. Of these, thirty-three were followed up after 12 months. Regression was used to estimate baseline individual and composite clinical scores (including cognitive, motor, and functional ability) using baseline C3t scores. Correlations between C3t and clinical scores were assessed using Spearman's R and visually inspected in relation to disease severity using scatterplots. Effect size over 12 months provided an indication of longitudinal behaviour of the C3t in relation to clinical measures.

RESULTS

Baseline C3t scores predicted baseline clinical scores to within 9-13% accuracy, being associated with individual and composite clinical scores. Changes in C3t scores over 12 months were small ([Formula: see text] ≤ 0.15) and mirrored the change in clinical scores.

CONCLUSION

The C3t demonstrates promise as a simple, easy to administer, objective outcome measure capable of predicting impairment that is reflective of Huntington's disease severity and offers a viable solution to support remote clinical monitoring. It may also offer utility as a screening tool for recruitment to clinical trials given preliminary indications of association with the prognostic index normed for Huntington's disease.

Composite UHDRS Correlates With Progression of Imaging Biomarkers in Huntington's Disease

BACKGROUND

The composite Unified Huntington's Disease Rating Scale (cUHDRS) is a multidimensional measure of progression in Huntington's disease (HD) being used as a primary outcome in clinical trials investigating potentially disease-modifying huntingtin-lowering therapies.

OBJECTIVE

Evaluating volumetric and structural connectivity correlates of the cUHDRS.

METHODS

One hundred and nineteen premanifest and 119 early-HD participants were included. Gray and white matter (WM) volumes were correlated with cUHDRS cross-sectionally and longitudinally using voxel-based morphometry. Correlations between baseline fractional anisotropy (FA); mean, radial, and axial diffusivity; and baseline cUHDRS were examined using tract-based spatial statistics.

RESULTS

Worse performance in the cUHDRS over time correlated with longitudinal volume decreases in the occipito-parietal cortex and centrum semiovale, whereas lower baseline scores correlated with decreased volume in the basal ganglia and surrounding WM. Lower cUHDRS scores were also associated with reduced FA and increased diffusivity at baseline.

CONCLUSION

The cUHDRS correlates with imaging biomarkers and tracks atrophy progression in HD supporting its biological relevance. © 2021 International Parkinson and Movement Disorder Society.

The use of wearable/portable digital sensors in Huntington's disease: A systematic review

In chronic neurological conditions, wearable/portable devices have potential as innovative tools to detect subtle early disease manifestations and disease fluctuations for the purpose of clinical diagnosis, care and therapeutic development. Huntington's disease (HD) has a unique combination of motor and non-motor features which, combined with recent and anticipated therapeutic progress, gives great potential for such devices to prove useful. The present work aims to provide a comprehensive account of the use of wearable/portable devices in HD and of what they have contributed so far. We conducted a systematic review searching MEDLINE, Embase, and IEEE Xplore. Thirty references were identified. Our results revealed large variability in the types of sensors used, study design, and the measured outcomes. Digital technologies show considerable promise for therapeutic research and clinical management of HD. However, more studies with standardized devices and harmonized protocols are needed to optimize the potential applicability of wearable/portable devices in HD.

•

Wearable/portable sensors have been proposed to detect and quantify manifestations of many neurodegenerative diseases.

•

No systematic review so far has examined their use in Huntington's disease (HD).

•

This work draws a broad picture of the digital wearable-based landscape in HD.

•

The utility of wearables in clinical practice and therapeutic research still needs to be proved.

•

Collaborative efforts are needed to further investigate their clinical use in HD.

Rapid and robust patterns of spontaneous locomotor deficits in mouse models of Huntington's disease

Huntington's disease (HD) is an inherited neurodegenerative disorder characterized by severe disruption of cognitive and motor functions, including changes in posture and gait. A number of HD mouse models have been engineered that display behavioral and neuropathological features of the disease, but gait alterations in these models are poorly characterized. Sensitive high-throughput tests of fine motor function and gait in mice might be informative in evaluating disease-modifying interventions. Here, we describe a hypothesis-free workflow that determines progressively changing locomotor patterns across 79 parameters in the R6/2 and Q175 mouse models of HD. R6/2 mice (120 CAG repeats) showed motor disturbances as early as at 4 weeks of age. Similar disturbances were observed in homozygous and heterozygous Q175 KI mice at 3 and 6 months of age, respectively. Interestingly, only the R6/2 mice developed forelimb ataxia. The principal components of the behavioral phenotypes produced two phenotypic scores of progressive postural instability based on kinematic parameters and trajectory waveform data, which were shared by both HD models. This approach adds to the available HD mouse model research toolbox and has a potential to facilitate the development of therapeutics for HD and other debilitating movement disorders with high unmet medical need.

Mutant huntingtin and neurofilament light have distinct longitudinal dynamics in Huntington's disease

The longitudinal dynamics of the most promising biofluid biomarker candidates for Huntington's disease (HD)-mutant huntingtin (mHTT) and neurofilament light (NfL)-are incompletely defined. Characterizing changes in these candidates during disease progression could increase our understanding of disease pathophysiology and help the identification of effective therapies. In an 80-participant cohort over 24 months, mHTT in cerebrospinal fluid (CSF), as well as NfL in CSF and blood, had distinct longitudinal trajectories in HD mutation carriers compared with controls. Baseline analyte values predicted clinical disease status, subsequent clinical progression, and brain atrophy, better than did the rate of change in analytes. Overall, NfL was a stronger monitoring and prognostic biomarker for HD than mHTT. Nonetheless, mHTT has prognostic value and might be a valuable pharmacodynamic marker for huntingtin-lowering trials.

Evaluation of mutant huntingtin and neurofilament proteins as potential markers in Huntington's disease

Huntington's disease (HD) is a genetic progressive neurodegenerative disorder, caused by a mutation in the HTT gene, for which there is currently no cure. The identification of sensitive indicators of disease progression and therapeutic outcome could help the development of effective strategies for treating HD. We assessed mutant huntingtin (mHTT) and neurofilament light (NfL) protein concentrations in cerebrospinal fluid (CSF) and blood in parallel with clinical evaluation and magnetic resonance imaging in premanifest and manifest HD mutation carriers. Among HD mutation carriers, NfL concentrations in plasma and CSF correlated with all nonbiofluid measures more closely than did CSF mHTT concentration. Longitudinal analysis over 4 to 8 weeks showed that CSF mHTT, CSF NfL, and plasma NfL concentrations were highly stable within individuals. In our cohort, concentration of CSF mHTT accurately distinguished between controls and HD mutation carriers, whereas NfL concentration, in both CSF and plasma, was able to segregate premanifest from manifest HD. In silico modeling indicated that mHTT and NfL concentrations in biofluids might be among the earliest detectable alterations in HD, and sample size prediction suggested that low participant numbers would be needed to incorporate these measures into clinical trials. These findings provide evidence that biofluid concentrations of mHTT and NfL have potential for early and sensitive detection of alterations in HD and could be integrated into both clinical trials and the clinic.

Adult-onset Huntington disease: An update

Appropriate nursing-care strategies depend on the early recognition of Huntington disease (HD) to prioritize a plan of care. This article offers perspective on the clinical presentation, prognosis, diagnosis, and management of adult-onset HD.