Progression of motor subtypes in Huntington's disease: a 6-year follow-up study

Identifying and verifying Huntington's disease subtypes: Clinical features, neuroimaging, and cytokine changes

AIMS

Huntington's disease (HD) is a progressive neurodegenerative disorder with heterogeneous clinical manifestations. Identifying distinct clinical clusters and their relevant biomarkers could elucidate the underlying disease pathophysiology.

METHODS

Following the Enroll-HD program initiated in 2018.09, we have recruited 104 HD patients (including 21 premanifest) and 31 health controls at Beijing Tiantan Hospital. Principal components analysis and k-means cluster analysis were performed to determine HD clusters. Chi-square test, one-way ANOVA, and covariance were used to identify features among these clusters. Furthermore, plasma cytokines levels and brain structural imaging were used as biomarkers to delineate the clinical features of each cluster.

RESULTS

Three clusters were identified. Cluster 1 demonstrated the most severe motor and nonmotor symptoms except for chorea, the lowest whole brain volume, the plasma levels of IL-2 were higher and significantly associated with cluster 1. Cluster 2 was characterized with the most severe chorea and the largest pallidum volume. Cluster 3 had the most benign motor symptoms but moderate psychiatric problems.

CONCLUSION

We have identified three HD clusters via clinical manifestations with distinct biomarkers. Our data shed light on better understanding about the pathophysiology of HD.

The Comprehensive Analysis of Motor and Neuropsychiatric Symptoms in Patients with Huntington's Disease from China: A Cross-Sectional Study

Huntington’s disease (HD) is an autosomal dominant inherited neurodegenerative disorder caused by CAG repeats expansion. There is a paucity of comprehensive clinical analysis in Chinese HD patients due to the low prevalence of HD in Asia. We aimed to comprehensively describe the motor, neuropsychiatric symptoms, and functional assessment in patients with HD from China. A total of 205 HD patients were assessed by the Unified Huntington’s Disease Rating Scale (UHDRS), the short version of Problem-Behavior Assessment (PBA-s), Hamilton Depression Scale (HAMD) and Beck Depression Inventory (BDI). Multivariate logistic regression analysis was used to explore the independent variables correlated with neuropsychiatric subscales. The mean age of motor symptom onset was 41.8 ± 10.0 years old with a diagnostic delay of 4.3 ± 3.8 years and a median CAG repeats of 44. The patients with a positive family history had a younger onset and larger CAG expansion than the patients without a family history (p < 0.05). There was a significant increase in total motor score across disease stages (p < 0.0001). Depression (51%) was the most common neuropsychiatric symptom at all stages, whereas moderate to severe apathy commonly occurred in advanced HD stages. We found lower functional capacity and higher HAMD were independently correlated with irritability; higher HAMD and higher BDI were independently correlated with affect; male sex and higher HAMD were independently correlated with apathy. In summary, comprehensive clinical profile analysis of Chinese HD patients showed not only chorea-like movement, but psychiatric symptoms were outstanding problems and need to be detected early. Our study provides the basis to guide clinical practice, especially in practical diagnostic and management processes.

Canadian healthcare capacity gaps for disease-modifying treatment in Huntington's disease: a survey of current practice and modelling of future needs

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.

Montreal Cognitive Assessment (MoCA) performance in Huntington's disease patients correlates with cortical and caudate atrophy

Huntington's Disease (HD) is an autosomal neurodegenerative disease characterized by motor, cognitive, and psychiatric symptoms. Cognitive impairment develops gradually in HD patients, progressing later into a severe cognitive dysfunction. The Montreal Cognitive Assessment (MoCA) is a brief screening test commonly employed to detect mild cognitive impairment, which has also been useful to assess cognitive decline in HD patients. However, the relationship between MoCA performance and brain structural integrity in HD patients remains unclear. Therefore, to explore this relationship we analyzed if cortical thinning and subcortical nuclei volume differences correlated with HD patients' MoCA performance. Twenty-two HD patients and twenty-two healthy subjects participated in this study. T1-weighted images were acquired to analyze cortical thickness and subcortical nuclei volumes. Group comparison analysis showed a significantly lower score in the MoCA global performance of HD patients. Also, the MoCA total score correlated with cortical thinning of fronto-parietal and temporo-occipital cortices, as well as with bilateral caudate volume differences in HD patients. These results provide new insights into the effectiveness of using the MoCA test to detect cognitive impairment and the brain atrophy pattern associated with the cognitive status of prodromal/early HD patients.

Juvenile-Onset Huntington Disease Pathophysiology and Neurodevelopment: A Review

Huntington disease is an autosomal dominant inherited brain disorder that typically becomes manifest in adulthood. Juvenile-onset Huntington disease refers to approximately 5% of patients with symptom onset before the age of 21 years. The causal factor is a pathologically expanded CAG repeat in the Huntingtin gene. Age at onset is inversely correlated with CAG repeat length. Juvenile-onset patients have distinct symptoms and signs with more severe pathology of involved brain structures in comparison with disease onset in adulthood. The aim of this review is to compare clinical and pathological features in juvenile- and adult-onset Huntington disease and to explore which processes potentially contribute to the observed differences. A specific focus is placed on molecular mechanisms of mutant huntingtin in early neurodevelopment and the interaction of a neurodegenerative disease and postnatal brain maturation. The importance of a better understanding of pathophysiological differences between juvenile- and adult-onset Huntington disease lies in development and implementation of new therapeutic strategies. © 2021 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Modeling Manifest Huntington's Disease Prevalence Using Diagnosed Incidence and Survival Time

INTRODUCTION

Understanding the epidemiology of Huntington's disease (HD) is key to assessing disease burden and the healthcare resources required to meet patients' needs. We aimed to develop and validate a model to estimate the diagnosed prevalence of manifest HD by the Shoulson-Fahn stage.

METHODS

A literature review identified epidemiological data from Brazil, Canada, France, Germany, Italy, Spain, the UK, and the USA. Data on staging distribution at diagnosis, progression, and mortality were derived from Enroll-HD. Newly diagnosed patients with manifest HD were simulated by applying annual diagnosed incidence rates to the total population in each country, each year from 1950 onwards. The number of diagnosed prevalent patients from the previous year who remained in each stage was estimated in line with the probability of death or progression. Diagnosed prevalence in 2020 was estimated as the sum of simulated patients, from all the incident cohorts, still alive.

RESULTS

The model estimates that in 2020, there were 66,787 individuals diagnosed with HD in the 8 included countries, of whom 62-63% were in Shoulson-Fahn stages 1 and 2 (with less severely limited functional capacity than those in stages 3-5). Diagnosed prevalence is estimated to be 8.2-9.0 per 100,000 in the USA, Canada, and the 5 included European countries and 3.5 per 100,000 in Brazil.

CONCLUSION

The modeled estimates generally accord with the previously published data. This analysis contributes to better understanding of the epidemiology of HD and highlights areas of uncertainty.

Imaging and Clinical Data on Swallowing Function of Individuals with Huntington's Disease and Dysphagia

BACKGROUND

Dysphagia is common in Huntington's disease (HD) affecting all phases of swallowing. Correlations exist between non-instrumental measures of dysphagia and clinical features of HD, including age, disease duration and degree of motor impairment. Lack of instrumental data limits our ability to wholly characterize HD-related dysphagia and prognosticate swallowing changes over time.

OBJECTIVE

To retrospectively describe a relatively large database of videofluoroscopic studies (VFSSs) and determine the relationships between dysphagia and HD clinical parameters, including disease duration and burden of pathology score.

METHODS

Medical and swallowing data of 49 individuals with HD and dysphagia were examined. VFSS data were interpreted using the Bethlehem Assessment Scale and Penetration-Aspiration Scale. Data from clinical bedside examination and social information were collated to describe the impact of dysphagia in HD. Repeated VFSS data were available for seven individuals.

RESULTS

Swallowing was characterized by lingual dysfunction, reduced soft palate elevation, delayed pharyngeal swallow initiation, and inability to clear matter from the pharynx. Two-thirds of cases presented with compromised airway protection with both liquid and solid consistencies. Tachyphagia and difficulty self-feeding were common. Dysphagia correlated with disease severity and duration. Longitudinal analysis revealed a mixed pattern of progression with some individuals presenting with worsening dysphagia whilst others appeared to remain stable or improved in function.

CONCLUSIONS

Dysphagia in HD is exacerbated by difficulties with self-feeding and monitoring feeding rate. Burden of pathology relates to pharyngeal swallow initiation and penetration and aspiration of fluid. Dysphagia did not appear to worsen in a systematic way in a subset of participants.

Does pallidal neuromodulation influence cognitive decline in Huntington's disease?

OBJECTIVE

Huntington's disease (HD) is an autosomal dominant neurodegenerative disorder associated with motor, psychiatric and cognitive deterioration over time. To date, Continuous Electrical Neuromodulation (CEN) of the globus pallidus internus (GPi) has been reported to improve chorea but little is known about cognitive progression in these patients. We propose to examine CEN impact on expected cognitive decline throughout long-term neuropsychological assessment of a cohort of HD patients.

METHOD

13 consecutive HD patients underwent GPi neuromodulation between January 2008 and February 2019. Over a 5-year follow-up period, they received systematic pre- and post-operative assessment according to the existing protocol in our unit. The main outcome measure was the total score obtained on the Mattis Dementia Rating Scale (MDRS) as an indicator of global cognitive function.

RESULTS

Chorea decreased in all patients postoperatively with a mean improvement of 56% despite disease progression over time, according to previous studies. Moreover we found that the global cognitive profile of HD patients treated with CEN was stable during the first 3 years of treatment.

CONCLUSION

We report an unexpected positive influence of GPi continuous electrical neuromodulation on the progression of global cognitive functioning in operated HD patients. This is the most important group of patients treated with this method to our knowledge whatever the sample size remains small. This result provides promising evidence of GPi-CEN efficacy not only in reducing chorea, but also in delaying cognitive decline in HD patients operated at an early stage of the disease.

Emerging therapies in Huntington's disease

Introduction: Huntington's disease (HD) is an inherited neurodegenerative condition for which there are no disease-modifying treatments. The availability of early genetic diagnosis makes HD an ideal candidate for early intervention. Growing understanding of pathogenesis has led to the identification of new therapeutic targets for which some compounds are now in clinical trials. Areas covered: A detailed review of medical databases and clinical trial registries was performed. Recent clinical trials aimed to establish disease-modification were included. Focus was assigned to RNA and DNA-based therapies aimed at lowering mutant huntingtin (mHTT) including antisense oligonucleotides (ASOs), RNA interference (RNAi), zinc finger proteins (ZFPs) and the CRISPR-Cas9 system. Modulation of mHTT and immunotherapies is also covered. Expert opinion: Targeting HD pathogenesis at its most proximal level is under intense investigation. ASOs are the only HTT-lowering strategy in clinical trials of manifest HD. Safety and efficacy of an allele specific vs. allele non-specific approach has yet to be established. Success will extend to premanifest carriers for which development of clinical and imaging biomarkers will be necessary. Scientific and technological advancement will bolster new methods of treatment delivery. Cumulative experience, collaborative research, and platforms such as ENROLL-HD will facilitate efficient and effective clinical trials.

Perceptions of the impact of chorea on health-related quality of life in Huntington disease (HD): A qualitative analysis of individuals across the HD spectrum, family members, and clinicians

Chorea, a hallmark symptom of Huntington's disease (HD), is characterized by jerky involuntary movements affecting the whole body that can interfere with daily functioning and impact health-related quality of life (HRQOL). To characterize chorea's impact on everyday functioning and HRQOL and identify patterns of perception and experiences of chorea among patients, caregivers, and providers. Data from focus groups of individuals with manifest HD (n = 8 early-stage HD; n = 16 late-stage HD), individuals at-risk or prodromal HD (n = 16), family HD caregivers (n = 17), and HD clinicians (n = 25). Focus group recordings were transcribed verbatim and analysed via constant comparison to identify meaningful and salient themes of living with chorea. Global themes of chorea's impact identified included: watching for chorea, experiences of stigma, and constraints on independence and relationships. Themes distinct to specific respondent groups included: Vigilance (at risk, prodromal); adaptation to chorea (early-stage); loss of autonomy and social life (late-stage); monitoring engagement (family caregivers) and safety (clinical providers). Living with chorea significantly constrains daily functioning, interactions, and HRQOL across the HD disease spectrum. Addressing these impacts via appropriate management of chorea can potentially enhance functioning, HRQOL, and overall satisfaction for persons with HD and their families.

Exercise in Huntington's Disease: Current State and Clinical Significance

Background

Huntington's disease (HD) is a rare, progressive neurodegenerative disease. Currently, there is no cure for the disease, but treatment may alleviate HD symptoms. In recent years, several exercise training interventions have been conducted in HD patients. In the current article, we review previous studies investigating targeted exercise training interventions in HD patients.

Methods

We performed a literature search using the PubMed, Scopus, Web of Science, and Google Scholar databases on exercise training interventions in HD patients. Six publications fulfilled the criteria and were included in the review.

Results

Exercise training resulted in beneficial effects on cardiovascular and mitochondrial function. Training effects on cognition, motor function, and body composition were less congruent, but a positive effect seems likely. Health-related quality of life during the training interventions was stable. Most studies reported no related adverse events in response to training.

Discussion

Exercise training seems to be safe and feasible in HD patients. However, current knowledge is mainly based on short, small-scale studies and it cannot be transferred to all HD patients. Therefore, longer-term interventions with larger HD patient cohorts are necessary to draw firm conclusions about the potentially positive effects of exercise training in HD patients.

Comparing Risperidone and Olanzapine to Tetrabenazine for the Management of Chorea in Huntington Disease: An Analysis from the Enroll-HD Database

INTRODUCTION

Huntington's chorea (HC) is commonly managed with neuroleptic medications, though there is little evidence to support their use. This study aimed to perform a real-world comparison of the efficacy of risperidone and olanzapine to tetrabenazine (TBZ) for HC.

METHODS

The Enroll-HD database was used to perform a propensity score-matched comparison of risperidone and olanzapine to TBZ, regarding their efficacy in controlling chorea. Participants with motor manifest Huntington's disease (HD) were grouped according to their use of risperidone, olanzapine, or TBZ. For the three groups, independent propensity score matching was performed on participants' baseline total functional score (TFC), baseline total motor score (TMS), disease burden score, CAG repeat length, baseline age, region, sex, and body mass index. Independent samples t test was used to calculate the differences between the groups in the annual rate of change of the TMS from the baseline to the second available visit.

RESULTS

The risperidone (n = 72) and olanzapine groups (n = 77) had annualized increases (worsening) in the TMS of only 1.47 points and 3.20 points, respectively, compared to 5.70 points in the two matched TBZ groups (n = 72) (P = 0.019) and (n = 77) (P = 0.143), respectively.

CONCLUSIONS

In the absence of prospective data, this analysis of the Enroll-HD database found that the neuroleptics risperidone and olanzapine seemed to at least be comparable to TBZ at controlling HC. These results demonstrate that neuroleptics may have comparable efficacy to TBZ for the treatment of HC. Further prospective studies are needed to confirm these findings.

Co-occurrence of mixed proteinopathies in late-stage Huntington's disease

Accumulating evidence highlights the potential role of mixed proteinopathies (i.e., abnormal protein aggregation) in the development of clinical manifestations of neurodegenerative diseases (NDD). Huntington's disease (HD) is an inherited NDD caused by autosomal-dominant expanded CAG trinucleotide repeat mutation in the gene coding for Huntingtin (Htt). Previous studies have suggested the coexistence of phosphorylated-Tau, α-synuclein (α-Syn) and TAR DNA-binding protein 43 (TDP-43) inclusions in HD. However, definite evidence that HD pathology in humans can be accompanied by other proteinopathies is still lacking. Using human post-mortem putamen samples from 31 controls and 56 HD individuals, we performed biochemical analyses of the expression, oligomerization and aggregation of Tau, α-Syn, TDP-43, and Amyloid precursor protein (APP)/Aβ. In HD brain, we observed reduced soluble protein (but not mRNA) levels of Htt, α-Syn, and Tau. Our results also support abnormal phosphorylation of Tau in more advanced stages of disease. Aberrant splicing of Tau exons 2, 3 (exclusion) and 10 (inclusion) was also detected in HD patients, leading to higher 0N4R and lower 1N3R isoforms. Finally, following formic acid extraction, we observed increased aggregation of TDP-43, α-Syn, and phosphorylated-Tau during HD progression. Notably, we observed that 88% of HD patients with Vonsattel grade 4 neuropathology displayed at least one non-Htt proteinopathy compared to 29% in controls. Interestingly, α-Syn aggregation correlated with Htt, TDP-43 and phosphorylated-Tau in HD but not in controls. The impact of this work is twofold: (1) it provides compelling evidences that Tau, α-Syn and TDP-43 proteinopathies are increased in HD, and (2) it suggests the involvement of common mechanisms leading to abnormal accumulation of aggregation-prone proteins in NDD. Further studies will be needed to decipher the impact of these proteinopathies on clinical manifestation of HD.

Treatment options for chorea

INTRODUCTION

Chorea is defined as jerk-like movements that move randomly from one body part to another. It is due to a variety of disorders and although current symptomatic therapy is quite effective there are few etiology- or pathogenesis-targeted therapies. The aim of this review is to summarize our own experience and published evidence in the treatment of chorea. Areas covered: After evaluating current guidelines and clinical practices for chorea of all etiologies, PubMed was searched for the most recent clinical trials and reviews using the term 'chorea' cross referenced with specific drug names. Expert commentary: Inhibitors of presynaptic vesicular monoamine transporter type 2 (VMAT2) that cause striatal dopamine depletion, such as tetrabenazine, deutetrabenazine, and valbenazine, are considered the treatment of choice in patients with chorea. Some clinicians also use dopamine receptor blockers (e.g. antipsychotics) and other drugs, including anti-epileptics and anti-glutamatargics. 'Dopamine stabilizers' such as pridopidine and other experimental drugs are currently being investigated in the treatment of chorea. Deep brain stimulation is usually reserved for patients with disabling chorea despite optimal medical therapy.

Driving with a neurodegenerative disorder: an overview of the current literature

Driving is important for employment, social activities, and for the feeling of independence. The decision to cease driving affects the quality of life and has been associated with reduced mobility, social isolation, and sadness. Patients with neurodegenerative disorders can experience difficulties while driving due to their cognitive, motor, and behavioral impairments. The aim of this review is to summarize the available literature on changes in driving competence and behavior in patients with neurodegenerative disorders, with a particular focus on Huntington's (HD), Parkinson's (PD), and Alzheimer's disease (AD). A systematic literature search was conducted in the PubMed/Medline database. Studies using on-road or simulated driving assessments were examined in this review. In addition, studies investigating the association between cognitive functioning and driving were included. The review identified 70 studies. Only a few publications were available on HD (n = 7) compared to PD (n = 32) and AD (n = 31). This review revealed that driving is impaired in patients with neurodegenerative disorders on all levels of driving competence. The errors most commonly committed were on the tactical level including lane maintenance and lane changing. Deficits in executive functioning, attention, and visuospatial abilities can partially predict driving competence, and the performance on neuropsychological tests might be useful when discussing potential driving cessation. Currently, there is no gold standard to assess driving ability using clinical measures such as neuropsychological assessments, so more studies are necessary to detect valid screening tools and develop useful and reliable evidence-based guidelines.

Patient-reported outcomes in Huntington's disease: Quality of life in neurological disorders (Neuro-QoL) and Huntington's disease health-related quality of life (HDQLIFE) physical function measures

BACKGROUND

There is a need for patient-reported outcome measures that capture the impact that motor impairments have on health-related quality of life in individuals with Huntington's disease.

OBJECTIVES

The objectives of this study were to establish the reliability and validity of new physical functioning patient-reported outcome measures in Huntington's disease.

METHODS

A total of 510 individuals with Huntington's disease completed 2 Quality of Life in Neurological Disorders (Lower Extremity Function and Upper Extremity Function) and 3 Huntington's Disease Health-Related Quality of Life (Chorea, Speech Difficulties, and Swallowing Difficulties) measures. Clinician-rated and generic self-report measures were also administered.

RESULTS

Reliabilities for the new patient reported physical functioning measures were excellent (all Cronbach's α > .92). Convergent, discriminant validity and known group validity was supported.

CONCLUSIONS

The results provide psychometric support for new patient-reported physical functioning measures and the fact that these measures can be used as clinically meaningful endpoints in Huntington's disease research and clinical practice. © 2017 International Parkinson and Movement Disorder Society.

Current Pharmacological Approaches to Reduce Chorea in Huntington's Disease

There are currently no effective pharmacological agents available to stop or prevent the progression of Huntington's disease (HD), a rare hereditary neurodegenerative disorder. In addition to psychiatric symptoms and cognitive impairments, HD causes progressive motor disturbances, in particular choreiform movements, which are characterized by unwanted contractions of the facial muscles, trunk and extremities. Management of choreiform movements is usually advised if chorea interferes with daily functioning, causes social isolation, gait instability, falls, or physical injury. Although drugs to reduce chorea are available, only few randomized controlled studies have assessed the efficacy of these drugs, resulting in a high variety of prescribed drugs in clinical practice. The current pharmacological treatment options to reduce chorea in HD are outlined in this review, including the latest results on deutetrabenazine, a newly developed pharmacological agent similar to tetrabenazine, but with suggested less peak dose side effects. A review of the existing literature was conducted using the PubMed, Cochrane and Medline databases. In conclusion, mainly tetrabenazine, tiapride (in European countries), olanzapine, and risperidone are the preferred first choice drugs to reduce chorea among HD experts. In the existing literature, these drugs also show a beneficial effect on motor symptom severity and improvement of psychiatric symptoms. Generally, it is recommended to start with a low dose and increase the dose with close monitoring of any adverse effects. New interesting agents, such as deutetrabenazine and pridopidine, are currently under development and more randomized controlled trials are warranted to assess the efficacy on chorea severity in HD.

Antipsychotic drugs in Huntington's disease

INTRODUCTION

The aim of this review is to overview the pharmacological features of neuroleptics experienced in the treatment of Huntington's disease (HD) symptoms. Despite a large number of case reports, randomized controlled trials (RCT) and drug comparison studies are lacking. Areas covered: After evaluating current guidelines and clinical unmet needs we searched PubMed for the term 'Huntington's disease' cross referenced with the terms 'Antipsychotic drugs' 'Neuroleptic drugs' and single drug specific names. Expert commentary: In clinical practice antipsychotics represent the first choice in the management of chorea in the presence of psychiatric symptoms, when poor compliance is suspected or when there is an increased risk of adverse events due to tetrabenazine. Antipsychotics are considered valid strategies, with the second generation preferred to reduce extrapyramidal adverse events, however they may cause more metabolic side effects. In the future 'dopamine stabilizers', such as pridopidine, could replace antipsychotics modulating dopamine transmission.