Prevalence of adult Huntington's disease in the UK based on diagnoses recorded in general practice records

PYK2 in the dorsal striatum of Huntington's disease R6/2 mouse model

Huntington's disease (HD) is a devastating disease due to autosomal dominant mutation in the HTT gene. Its pathophysiology involves multiple molecular alterations including transcriptional defects. We previously showed that in HD patients and mouse model, the protein levels of the non-receptor tyrosine kinase PYK2 were decreased in the hippocampus and that viral expression of PYK2 improved the hippocampal phenotype. Here, we investigated the possible contribution of PYK2 in the striatum, a brain region particularly altered in HD. PYK2 mRNA levels were decreased in the striatum and hippocampus of R6/2 mice, a severe HD model. Striatal PYK2 protein levels were also decreased in R6/2 mice and human patients. PYK2 knockout by itself did not result in motor symptoms observed in HD mouse models. We examined whether PYK2 deficiency participated in the R6/2 mice phenotype by expressing PYK2 in their dorsal striatum using AAV vectors. With an AAV1/Camk2a promoter, we did not observe significant improvement of body weight, clasping, motor activity and coordination (rotarod) alterations observed in R6/2 mice. With an AAV9/SYN1 promoter we found a slightly higher body weight and a trend to better rotarod performance. Both viruses similarly transduced striatal projection neurons and somatostatin-positive interneurons but only AAV9/SYN1 led to PYK2 expression in cholinergic and parvalbumin-positive interneurons. Expression of PYK2 in cholinergic interneurons may contribute to the slight effects observed. We conclude that PYK2 mRNA and protein levels are decreased in the striatum as in hippocampus of HD patients and mouse models. However, in contrast to hippocampus, striatal viral expression of PYK2 has only a minor effect on the R6/2 model striatal phenotype.

Transcriptome Study in Sicilian Patients with Huntington's Disease

Background/Objectives: Huntington's disease (HD) is an autosomal dominant neurodegenerative disorder caused by the expansion of the CAG nucleotide repeat in the first exon of the huntingtin (HTT) gene. The disease typically manifests between the second and third decades of life and progresses gradually. The pathogenesis of HD involves the dysregulation of gene expression, influenced by various molecular processes ranging from transcription to protein stability. Methods: To investigate potential variations in gene expression associated with HD, a transcriptome study was conducted using peripheral blood mononuclear cell samples from 15 HD patients and 15 controls, all of Sicilian origin. Results: The analysis identified 7179 statistically significant differentially expressed genes between the two groups. Gene Set Enrichment Analysis (GSEA) and Gene Ontology (GO) terms were applied to identify the pathways affected by these differentially expressed mRNAs. The GSEA results highlighted significant associations between HD and GO pathways related to ribosomal functions and structure. These pathways were predominantly characterized by negative expression, with a substantial number of genes showing dysregulation. This suggests that the molecular processes leading to protein translation via ribosomes may be impaired in HD. Furthermore, dysregulation was observed in genes and non-coding RNAs involved in regulatory roles across various transcriptional processes. Conclusions: These findings support the hypothesis that the entire process, from transcription to translation, is disrupted in HD patients carrying the CAG repeat expansion in the first exon of the HTT gene.

Pharmacological Treatment of Neuropsychiatric Symptoms in Huntington's Disease: A Systematic Review

BACKGROUND

Studies focusing on the treatment of neuropsychiatric symptoms (NPS) in Huntington's disease (HD) are scarce and show a wide variation in design, outcome measures and methodological quality. The effectiveness of pharmacological treatment of NPS in HD has not been systematically reviewed so far.

OBJECTIVE

To provide an overview of the available literature on the effectiveness of pharmacological treatment of NPS in HD.

METHODS

PubMed and the Cochrane library were systematically searched for studies assessing the effects of pharmacotherapy of NPS, both as a primary and as secondary outcome. A risk of bias assessment was performed for each article.

RESULTS

Fifteen articles qualified for critical evaluation: 10 randomized controlled trials (RCTs) (five placebo-controlled and five cross-over) and five open label studies. One RCT reported improvement of the overall NPS with nabilone treatment; another RCT reported that fluoxetine slightly improved irritability. Lower-level evidence from open studies suggests that the atypical antipsychotics cariprazine, olanzapine and risperidone may improve overall NPS, and that cariprazine, venlafaxine XR and olanzapine may improve depression. In addition, olanzapine may improve obsessive thoughts, aggression, anxiety and irritability.

CONCLUSIONS

We conclude that although NPS in HD are common, hardly any clinical trials have addressed their treatment. As a result, convincing evidence that could guide clinical practice is lacking. More focused, and larger, multicenter trials focusing on NPS are urgently needed to generate the knowledge necessary to support the development of evidence-based clinical treatment guidelines.

Evaluation of an Antisense Oligonucleotide Targeting CAG Repeats: A Patient-Customized Therapy Study for Huntington's Disease

Huntington's disease is a genetic disorder characterized by progressive neuronal cell damage in some areas of the brain; symptoms are commonly associated with chorea, rigidity and dystonia. The symptoms in Huntington's Disease are caused by a pathological increase in the number of Cytokine-Adenine-Guanine (CAG) repeats on the first exon of the Huntingtin gene, which causes a protein to have an excessive number of glutamine residues; this alteration leads to a change in the protein's conformation and function. Therefore, the purpose of this work was to design, synthesize and evaluate an antisense oligonucleotide (ASO; 95 nucleotides) HTT 90-5 directed to the Huntingtin CAG repeats in primary leukocyte culture cells from a patient with Huntington's Disease; approximately 500,000 leukocytes per well extracted from venous blood were used, to which 100 pMol of ASO were administered, and the expression of Huntingtin was subsequently evaluated at 72 h by RT-PCR. Our results showed that the administration of the HTT 90-5 antisense decreased the expression of Huntingtin mRNA in the primary culture leukocyte cells from our patient. These results suggest that the use of long antisense targeting the CAG Huntingtin cluster may be an option to decrease the expression of Huntingtin and probably could be adjusted depending on the number of CAG repeats in the cluster.

Are people living with Huntington's disease experiencing person-centered integrated care?

Background: Huntington's disease (HD) is among the most complex long-term neurological conditions, necessitating care and management from multiple partners within and beyond the health sector. However, there is a paucity of evidence describing how individuals receive this multifaceted care and whether current care provision adequately meets their needs. Objective: To understand if current care provision is meeting the complex needs of people living with HD in England and assess their perceived need for integrated care. Methods: A cross-sectional survey was co-designed with patient and public representatives, as part of a mixed-methods study to explore what integrated care means for people living with HD. The survey was distributed online and via charities, collecting quantitative and qualitative data. Descriptive statistics and content analysis were performed. Results: A total of 153 people, from 45 counties in England, participated in the survey. When assessing person-centered coordinated care, 65% of respondents rated their care as very poor, poor, or expressed a neutral opinion; carers reported the lowest scores. Although 58% of the participants said it was extremely important to have a care coordinator, only 19% of people reported having one, with these coordinators being identified in only 40% of the counties. Nevertheless, people with access to a care coordinator reported markedly improved care experiences. Conclusions: People living with HD commonly report fragmented care, geographical inequalities in care access, and unmet complex needs. Future research should focus on developing an HD integrated care model tailored to address these complex needs, including an evaluation of the cost-effectiveness of an HD care coordinator.

Advancements in Targeting Ion Channels for the Treatment of Neurodegenerative Diseases

Ion channels are integral membrane proteins embedded in biological membranes, and they comprise specific proteins that control the flow of ion transporters in and out of cells, playing crucial roles in the biological functions of different cells. They maintain the homeostasis of water and ion metabolism by facilitating ion transport and participate in the physiological processes of neurons and glial cells by regulating signaling pathways. Neurodegenerative diseases are a group of disorders characterized by the progressive loss of neurons in the central nervous system (CNS) or peripheral nervous system (PNS). Despite significant progress in understanding the pathophysiological processes of various neurological diseases in recent years, effective treatments for mitigating the damage caused by these diseases remain inadequate. Increasing evidence suggests that ion channels are closely associated with neuroinflammation; oxidative stress; and the characteristic proteins in neurodegenerative diseases, including Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), amyotrophic lateral sclerosis (ALS), and multiple sclerosis (MS). Therefore, studying the pathogenic mechanisms closely related to ion channels in neurodegenerative diseases can help identify more effective therapeutic targets for treating neurodegenerative diseases. Here, we discuss the progress of research on ion channels in different neurodegenerative diseases and emphasize the feasibility and potential of treating such diseases from the perspective of ion channels.

Trial to assess the tolerability of using felodipine to upregulate autophagy as a treatment of Huntington's disease (FELL-HD): a phase II, single-centre, open-label, dose-finding trial protocol

INTRODUCTION

Huntington's disease (HD) is an autosomal dominant neurodegenerative disorder that presents with a progressive movement disorder along with cognitive and psychiatric problems. It is caused by a Cytosine-adenin-guanine (CAG) expansion in exon 1 of the huntingtin gene which codes for mutant huntingtin (mHTT) that over time accumulates in cells, causing dysfunction and then death through new toxic gain-of-function mechanisms. Autophagy has been shown to be critical for the degradation of diverse intracytoplasmic aggregate-prone proteins that cause neurodegenerative disease, including mHTT. From a screen of a library enriched in approved drugs, felodipine was selected as the most suitable candidate showing strong autophagy-inducing effects in preclinical models of HD. We are, therefore, conducting a trial to assess the safety and tolerability of felodipine in people with early HD.

METHODS AND ANALYSIS

FELL-HD is a phase II, single-centre, open-label, dose-finding trial in people with early HD. 18 participants with early clinical features of the disease will be treated with felodipine for 58 weeks, with a further 4-week follow-up. The primary outcome measure is the number of adverse events attributable to felodipine. Exploratory outcomes include additional measures of motor and cognitive function, non-motor symptoms and quality of life scales, as well as peripheral and central disease biomarkers assessed through brain MRI. Analysis of blood and cerebrospinal fluid will also be performed through an associated sample study, FELL HD-s.

ETHICS AND DISSEMINATION

The study was approved by the London-Brent Research Ethics Committee (reference 22/LO/0387) and has been accepted by the Medicines and Healthcare products Regulatory Agency for clinical trials authorisation (reference CTA 12854/0256/001-0001). A lay summary of the results of the trial will be uploaded to our research group website which is publicly accessible. A webinar or in-person open day, to present results of the trial to participants and our wider cohort of patients who attend our centre, will be held once the trial is completed. The results of the trial will also be published in scientific journals and presented at national and international conferences.

TRIAL REGISTRATION NUMBERS

EudraCT-2021-000897-27, ISRCTN56240656.

Advances in Gene and Cellular Therapeutic Approaches for Huntington's Disease

Huntington's disease (HD) is an inherited neurodegenerative disorder caused by the abnormal expansion of CAG trinucleotide repeats in the Huntingtin gene (HTT) located on chromosome 4. It is transmitted in an autosomal dominant manner and is characterized by motor dysfunction, cognitive decline, and emotional disturbances. To date, there are no curative treatments for HD have been developed; current therapeutic approaches focus on symptom relief and comprehensive care through coordinated pharmacological and non-pharmacological methods to manage the diverse phenotypes of the disease. International clinical guidelines for the treatment of HD are continually being revised in an effort to enhance care within a multidisciplinary framework. Additionally, innovative gene and cell therapy strategies are being actively researched and developed to address the complexities of the disorder and improve treatment outcomes. This review endeavours to elucidate the current and emerging gene and cell therapy strategies for HD, offering a detailed insight into the complexities of the disorder and looking forward to future treatment paradigms. Considering the complexity of the underlying mechanisms driving HD, a synergistic treatment strategy that integrates various factors-such as distinct cell types, epigenetic patterns, genetic components, and methods to improve the cerebral microenvironment-may significantly enhance therapeutic outcomes. In the future, we eagerly anticipate ongoing innovations in interdisciplinary research that will bring profound advancements and refinements in the treatment of HD.

Circadian rhythm alterations affecting the pathology of neurodegenerative diseases

The circadian rhythm is a nearly 24-h oscillation found in various physiological processes in the human brain and body that is regulated by environmental and genetic factors. It is responsible for maintaining body homeostasis and it is critical for essential functions, such as metabolic regulation and memory consolidation. Dysregulation in the circadian rhythm can negatively impact human health, resulting in cardiovascular and metabolic diseases, psychiatric disorders, and premature death. Emerging evidence points to a relationship between the dysregulation circadian rhythm and neurodegenerative diseases, suggesting that the alterations in circadian function might play crucial roles in the pathogenesis and progression of neurodegenerative diseases. Better understanding this association is of paramount importance to expand the knowledge on the pathophysiology of neurodegenerative diseases, as well as, to provide potential targets for the development of new interventions based on the dysregulation of circadian rhythm. Here we review the latest findings on dysregulation of circadian rhythm alterations in Parkinson's disease, Alzheimer's disease, Huntington's disease, amyotrophic lateral sclerosis, multiple sclerosis, spinocerebellar ataxia and multiple-system atrophy, focusing on research published in the last 3 years.

Increased frequency of repeat expansion mutations across different populations

Repeat expansion disorders (REDs) are a devastating group of predominantly neurological diseases. Together they are common, affecting 1 in 3,000 people worldwide with population-specific differences. However, prevalence estimates of REDs are hampered by heterogeneous clinical presentation, variable geographic distributions, and technological limitations leading to under-ascertainment. Here, leveraging whole genome sequencing data from 82,176 individuals from different populations, we found an overall disease allele frequency of REDs of 1 in 283 individuals. Modelling disease prevalence using genetic data, age at onset and survival, we show that the expected number of people with REDs would be two to three times higher than currently reported figures, indicating under-diagnosis and/or incomplete penetrance. While some REDs are population-specific, e.g. Huntington disease-like 2 in Africans, most REDs are represented in all broad genetic ancestries (i.e. Europeans, Africans, Americans, East Asians, and South Asians), challenging the notion that some REDs are found only in specific populations. These results have worldwide implications for local and global health communities in the diagnosis and counselling of REDs.

PET Ligands for Imaging Mutant Huntingtin Aggregates: A Case Study in Non-For-Profit Scientific Management

Positron emission tomography imaging of misfolded proteins with high-affinity and selective radioligands has played a vital role in expanding our knowledge of neurodegenerative diseases such as Parkinson's and Alzheimer's disease. The pathogenesis of Huntington's disease, a CAG trinucleotide repeat disorder, is similarly linked to the presence of protein fibrils formed from mutant huntingtin (mHTT) protein. Development of mHTT fibril-specific radioligands has been limited by the lack of structural knowledge around mHTT and a dearth of available hit compounds for medicinal chemistry refinement. Over the past decade, the CHDI Foundation, a non-for-profit scientific management organisation has orchestrated a large-scale screen of small molecules to identify high affinity ligands of mHTT, with lead compounds now reaching clinical maturity. Here we describe the mHTT radioligands developed to date and opportunities for further improvement of this radiotracer class.

Sex-Specific Differences in the Progression of Huntington's Disease Symptoms - A National Study in China

INTRODUCTION

Huntington's disease (HD) is a rare, inherited neurodegenerative disorder. Despite extensive research on symptom progression and sex differences in Western populations, little is known about these aspects within the Chinese context. The objective of this study was to investigate the temporal trends of symptoms in individuals with HD in China.

METHODS

A nationwide cross-sectional study was conducted in Chinese individuals diagnosed with HD. Symptom progression over time, encompassing physical, psychiatric, and cognitive symptoms, was self-reported. We calculated the proportions of individuals who currently had each symptom by disease duration, and tested corresponding temporal trends by linear regression analyses.

RESULTS

A total of 269 individuals diagnosed with HD were included. Specific symptoms were found to progress more significantly in males compared to females over time, including psychotic symptoms (p = 0.007), urinary incontinence (p = 0.013), reduced concentration (p = 0.005), font alteration (p = 0.029), atypical facial expression (p = 0.037), and suicidal ideation (p = 0.047). In terms of cognitive and psychiatric symptoms, no significant temporal trends were identified in females, while males demonstrated significant increasing trends, with reduced concentration (p = 0.005) and psychotic symptoms (p = 0.007) standing out.

CONCLUSIONS

This study emphasizes the existence of sex-specific symptom progression in HD within the Chinese population, underscoring the importance of considering sex in clinical practice. Further research should investigate the mechanisms behind these differences and explore tailored treatment options.

INTRODUCTION

Huntington's disease (HD) is a rare, inherited neurodegenerative disorder. Despite extensive research on symptom progression and sex differences in Western populations, little is known about these aspects within the Chinese context. The objective of this study was to investigate the temporal trends of symptoms in individuals with HD in China.

METHODS

A nationwide cross-sectional study was conducted in Chinese individuals diagnosed with HD. Symptom progression over time, encompassing physical, psychiatric, and cognitive symptoms, was self-reported. We calculated the proportions of individuals who currently had each symptom by disease duration, and tested corresponding temporal trends by linear regression analyses.

RESULTS

A total of 269 individuals diagnosed with HD were included. Specific symptoms were found to progress more significantly in males compared to females over time, including psychotic symptoms (p = 0.007), urinary incontinence (p = 0.013), reduced concentration (p = 0.005), font alteration (p = 0.029), atypical facial expression (p = 0.037), and suicidal ideation (p = 0.047). In terms of cognitive and psychiatric symptoms, no significant temporal trends were identified in females, while males demonstrated significant increasing trends, with reduced concentration (p = 0.005) and psychotic symptoms (p = 0.007) standing out.

CONCLUSIONS

This study emphasizes the existence of sex-specific symptom progression in HD within the Chinese population, underscoring the importance of considering sex in clinical practice. Further research should investigate the mechanisms behind these differences and explore tailored treatment options.

Huntington's disease: A clinical primer for acute and general physicians

Huntington's disease (HD) usually manifests in adulthood and is characterised by progressive neurodegeneration in the brain that causes worsening involuntary movements, mental health and cognition over many years. Depression, anxiety and apathy are common. HD is autosomal dominant and affects about 1 in 8,000 people in the UK. There are currently no disease-modifying treatments and so patient care centres on multidisciplinary therapy support and medical treatments to relieve distressing symptoms. Progression of HD is usually slow, and so acute deteriorations often indicate another problem, such as intercurrent infections, constipation, urinary retention, gastro-oesophageal reflux disease or poor dentition. In this review we outline common presentations in HD patients, both acute and chronic, consider therapeutic options and discuss specific considerations in advanced HD.

The cytosolic DNA-sensing cGAS-STING pathway in neurodegenerative diseases

BACKGROUND

With the widespread prevalence of neurodegenerative diseases (NDs) and high rates of mortality and disability, it is imminent to find accurate targets for intervention. There is growing evidence that neuroimmunity is pivotal in the pathology of NDs and that interventions targeting neuroimmunity hold great promise. Exogenous or dislocated nucleic acids activate the cytosolic DNA sensor cyclic GMP-AMP synthase (cGAS), activating the stimulator of interferon genes (STING). The activated STING triggers innate immune responses and then the cGAS-STING signaling pathway links abnormal nucleic acid sensing to the immune response. Recently, numerous studies have shown that neuroinflammation regulated by cGAS-STING signaling plays an essential role in NDs.

AIMS

In this review, we summarized the mechanism of cGAS-STING signaling in NDs and focused on inhibitors targeting cGAS-STING.

CONCLUSION

The cGAS-STING signaling plays an important role in the pathogenesis of NDs. Inhibiting the cGAS-STING signaling may provide new measures in the treatment of NDs.

A clinical study and future prospects for bioactive compounds and semi-synthetic molecules in the therapies for Huntington's disease

A neurodegenerative disorder (ND) refers to Huntington's disease (HD) which affects memory loss, weight loss, and movement dysfunctions such as chorea and dystonia. In the striatum and brain, HD most typically impacts medium-spiny neurons. Molecular genetics, excitotoxicity, oxidative stress (OS), mitochondrial, and metabolic dysfunction are a few of the theories advanced to explicit the pathophysiology of neuronal damage and cell death. Numerous in-depth studies of the literature have supported the therapeutic advantages of natural products in HD experimental models and other treatment approaches. This article briefly discusses the neuroprotective impacts of natural compounds against HD models. The ability of the discovered natural compounds to suppress HD was tested using either in vitro or in vivo models. Many bioactive compounds considerably lessened the memory loss and motor coordination brought on by 3-nitropropionic acid (3-NP). Reduced lipid peroxidation, increased endogenous enzymatic antioxidants, reduced acetylcholinesterase activity, and enhanced mitochondrial energy generation have profoundly decreased the biochemical change. It is significant since histology showed that therapy with particular natural compounds lessened damage to the striatum caused by 3-NP. Moreover, natural products displayed varying degrees of neuroprotection in preclinical HD studies because of their antioxidant and anti-inflammatory properties, maintenance of mitochondrial function, activation of autophagy, and inhibition of apoptosis. This study highlighted about the importance of bioactive compounds and their semi-synthetic molecules in the treatment and prevention of HD.

Pooling of primary care electronic health record (EHR) data on Huntington's disease (HD) and cancer: establishing comparability of two large UK databases

OBJECTIVES

To explore whether UK primary care databases arising from two different software systems can be feasibly combined, by comparing rates of Huntington's disease (HD, which is rare) and 14 common cancers in the two databases, as well as characteristics of people with these conditions.

DESIGN

Descriptive study.

SETTING

Primary care electronic health records from Clinical Practice Research Datalink (CPRD) GOLD and CPRD Aurum databases, with linked hospital admission and death registration data.

PARTICIPANTS

4986 patients with HD and 1 294 819 with an incident cancer between 1990 and 2019.

PRIMARY AND SECONDARY OUTCOME MEASURES

Incidence and prevalence of HD by calendar period, age group and region, and annual age-standardised incidence of 14 common cancers in each database, and in a subset of 'overlapping' practices which contributed to both databases. Characteristics of patients with HD or incident cancer: medical history, recent prescribing, healthcare contacts and database follow-up.

RESULTS

Incidence and prevalence of HD were slightly higher in CPRD GOLD than CPRD Aurum, but with similar trends over time. Cancer incidence in the two databases differed between 1990 and 2000, but converged and was very similar thereafter. Participants in each database were most similar in terms of medical history (median standardised difference, MSD 0.03 (IQR 0.01-0.03)), recent prescribing (MSD 0.06 (0.03-0.10)) and demographics and general health variables (MSD 0.05 (0.01-0.09)). Larger differences were seen for healthcare contacts (MSD 0.27 (0.10-0.41)), and database follow-up (MSD 0.39 (0.19-0.56)).

CONCLUSIONS

Differences in cancer incidence trends between 1990 and 2000 may relate to use of a practice-level data quality filter (the 'up-to-standard' date) in CPRD GOLD only. As well as the impact of data curation methods, differences in underlying data models can make it more challenging to define exactly equivalent clinical concepts in each database. Researchers should be aware of these potential sources of variability when planning combined database studies and interpreting results.

Metabolomics: An Emerging "Omics" Platform for Systems Biology and Its Implications for Huntington Disease Research

Huntington's disease (HD) is a progressive, fatal neurodegenerative disease characterized by motor, cognitive, and psychiatric symptoms. The precise mechanisms of HD progression are poorly understood; however, it is known that there is an expansion of the trinucleotide cytosine-adenine-guanine (CAG) repeat in the Huntingtin gene. Important new strategies are of paramount importance to identify early biomarkers with predictive value for intervening in disease progression at a stage when cellular dysfunction has not progressed irreversibly. Metabolomics is the study of global metabolite profiles in a system (cell, tissue, or organism) under certain conditions and is becoming an essential tool for the systemic characterization of metabolites to provide a snapshot of the functional and pathophysiological states of an organism and support disease diagnosis and biomarker discovery. This review briefly highlights the historical progress of metabolomic methodologies, followed by a more detailed review of the use of metabolomics in HD research to enable a greater understanding of the pathogenesis, its early prediction, and finally the main technical platforms in the field of metabolomics.

Aberrant splicing of mutant huntingtin in Huntington's disease knock-in pigs

Huntington's disease (HD) is an autosomal-dominant inherited neurodegenerative disease caused by a CAG repeat expansion in exon1 of the huntingtin gene (HTT). This expansion leads to the production of N-terminal mutant huntingtin protein (mHtt) that contains an expanded polyglutamine tract, which is toxic to neurons and causes neurodegeneration. While the production of N-terminal mHtt can be mediated by proteolytic cleavage of full-length mHtt, abnormal splicing of exon1-intron1 of mHtt has also been identified in the brains of HD mice and patients. However, the proportion of aberrantly spliced exon1 mHTT in relation to normal mHTT exon remains to be defined. In this study, HTT exon1 production was examined in the HD knock-in (KI) pig model, which more closely recapitulates neuropathology seen in HD patient brains than HD mouse models. The study revealed that aberrant spliced HTT exon1 is also present in the brains of HD pigs, but it is expressed at a much lower level than the normally spliced HTT exon products. These findings suggest that careful consideration is needed when assessing the contribution of aberrantly spliced mHTT exon1 to HD pathogenesis, and further rigorous investigation is required.

From Pathogenesis to Therapeutics: A Review of 150 Years of Huntington's Disease Research

Huntington's disease (HD) is a debilitating neurodegenerative genetic disorder caused by an expanded polyglutamine-coding (CAG) trinucleotide repeat in the huntingtin (HTT) gene. HD behaves as a highly penetrant dominant disorder likely acting through a toxic gain of function by the mutant huntingtin protein. Widespread cellular degeneration of the medium spiny neurons of the caudate nucleus and putamen are responsible for the onset of symptomology that encompasses motor, cognitive, and behavioural abnormalities. Over the past 150 years of HD research since George Huntington published his description, a plethora of pathogenic mechanisms have been proposed with key themes including excitotoxicity, dopaminergic imbalance, mitochondrial dysfunction, metabolic defects, disruption of proteostasis, transcriptional dysregulation, and neuroinflammation. Despite the identification and characterisation of the causative gene and mutation and significant advances in our understanding of the cellular pathology in recent years, a disease-modifying intervention has not yet been clinically approved. This review includes an overview of Huntington's disease, from its genetic aetiology to clinical presentation and its pathogenic manifestation. An updated view of molecular mechanisms and the latest therapeutic developments will also be discussed.

Pain in Huntington's disease and its potential mechanisms

Pain is common and frequent in many neurodegenerative diseases, although it has not received much attention. In Huntington's disease (HD), pain is often ignored and under-researched because attention is more focused on motor and cognitive decline than psychiatric symptoms. In HD progression, pain symptoms are complex and involved in multiple etiologies, particularly mental issues such as apathy, anxiety and irritability. Because of psychiatric issues, HD patients rarely complain of pain, although their bodies show severe pain symptoms, ultimately resulting in insufficient awareness and lack of research. In HD, few studies have focused on pain and pain-related features. A detailed and systemic pain history is crucial to assess and explore pain pathophysiology in HD. This review provides an overview concentrating on pain-related factors in HD, including neuropathology, frequency, features, affecting factors and mechanisms. More attention and studies are still needed in this interesting field in the future.

The brain on time: links between development and neurodegeneration

Neurodegenerative diseases are characterized by the progressive loss of structure or function of neurons. In this Spotlight, we explore the idea that genetic forms of neurodegenerative disorders might be rooted in neural development. Focusing on Alzheimer's, Parkinson's and Huntington's disease, we first provide a brief overview of the pathology for these diseases. Although neurodegenerative diseases are generally thought of as late-onset diseases, we discuss recent evidence promoting the notion that they might be considered neurodevelopmental disorders. With this view in mind, we consider the suitability of animal models for studying these diseases, highlighting human-specific features of human brain development. We conclude by proposing that one such feature, human-specific regulation of neurogenic time, might be key to understanding the etiology and pathophysiology of human neurodegenerative disease.

Normal range CAG repeat size variations in the HTT gene are associated with an adverse lipoprotein profile partially mediated by body mass index

Tandem cytosine-adenine-guanine (CAG) repeat sizes of 36 or more in the huntingtin gene (HTT) cause Huntington's disease (HD). Apart from neuropsychiatric complications, the disease is also accompanied by metabolic dysregulation and weight loss, which contribute to a progressive functional decline. Recent studies also reported an association between repeats below the pathogenic threshold (<36) for HD and body mass index (BMI), suggesting that HTT repeat sizes in the non-pathogenic range are associated with metabolic dysregulation. In this study, we hypothesized that HTT repeat sizes < 36 are associated with metabolite levels, possibly mediated through reduced BMI. We pooled data from three European cohorts (n = 10 228) with genotyped HTT CAG repeat size and metabolomic measurements. All 145 metabolites were measured on the same targeted platform in all studies. Multilevel mixed-effects analysis using the CAG repeat size in HTT identified 67 repeat size metabolite associations. Overall, the metabolomic profile associated with larger CAG repeat sizes in HTT were unfavorable-similar to those of higher risk of coronary artery disease and type 2 diabetes-and included elevated levels of amino acids, fatty acids, low-density lipoprotein (LDL)-, very low-density lipoprotein- and intermediate density lipoprotein (IDL)-related metabolites while with decreased levels of very large high-density lipoprotein (HDL)-related metabolites. Furthermore, the associations of 50 metabolites, in particular, specific very large HDL-related metabolites, were mediated by lower BMI. However, no mediation effect was found for 17 metabolites related to LDL and IDL. In conclusion, our findings indicate that large non-pathogenic CAG repeat sizes in HTT are associated with an unfavorable metabolomic profile despite their association with a lower BMI.

Global Epidemiology of Movement Disorders: Rare or Underdiagnosed?

In this manuscript, we review the epidemiology of movement disorders including Parkinson's disease (PD), atypical parkinsonism, essential tremor, dystonia, functional movement disorders, tic disorders, chorea, and ataxias. We emphasize age-, sex-, and geography-based incidence and prevalence, as well as notable trends including the rising incidence and prevalence of PD. Given the growing global interest in refining clinical diagnostic skills in recognizing movement disorders, we highlight some key epidemiological findings that may be of interest to clinicians and health systems tasked with diagnosing and managing the health of patients with movement disorders.

Cell Rearrangement and Oxidant/Antioxidant Imbalance in Huntington's Disease

Huntington's Disease (HD) is a hereditary neurodegenerative disorder caused by the expansion of a CAG triplet repeat in the HTT gene, resulting in the production of an aberrant huntingtin (Htt) protein. The mutant protein accumulation is responsible for neuronal dysfunction and cell death. This is due to the involvement of oxidative damage, excitotoxicity, inflammation, and mitochondrial impairment. Neurons naturally adapt to bioenergetic alteration and oxidative stress in physiological conditions. However, this dynamic system is compromised when a neurodegenerative disorder occurs, resulting in changes in metabolism, alteration in calcium signaling, and impaired substrates transport. Thus, the aim of this review is to provide an overview of the cell's answer to the stress induced by HD, focusing on the role of oxidative stress and its balance with the antioxidant system.

Comorbidities and clinical outcomes in adult- and juvenile-onset Huntington's disease: a study of linked Swedish National Registries (2002-2019)

BACKGROUND

Huntington's disease (HD) is a rare, neurodegenerative disease and its complex motor, cognitive and psychiatric symptoms exert a lifelong clinical burden on both patients and their families.

OBJECTIVE

To describe the clinical burden and natural history of HD.

METHODS

This longitudinal cohort study used data from the linked Swedish national registries to describe the occurrence of comorbidities (acute and chronic), symptomatic treatments and mortality in an incident cohort of individuals who either received the first diagnosis of HD above (adult onset HD; AoHD) or below (juvenile-onset HD; JoHD) 20 years of age, compared with a matched cohort without HD from the general population. Disease burden of all individuals alive in Sweden was described during a single calendar year (2018), including the occurrence of key symptoms, treatments and hospitalizations.

RESULTS

The prevalence of HD in 2018 was approximately 10.2 per 100,000. Of 1492 individuals with a diagnosis of HD during 2002 and 2018, 1447 had AoHD and 45 had JoHD. Individuals with AoHD suffered a higher incidence of obsessive-compulsive disorder, acute psychotic episodes, pneumonia, constipation and fractures compared with matched controls. Individuals with JoHD had higher incidence rates of epilepsy, constipation and acute respiratory symptoms. Median time to all-cause mortality in AoHD was 12.1 years from diagnosis. Patients alive with HD in Sweden in 2018 displayed a pattern of increased clinical burden for a number of years since diagnosis.

CONCLUSIONS

This study demonstrates the significant and progressive clinical burden in individuals with HD and presents novel insights into the natural history of JoHD.

The updated development of blood-based biomarkers for Huntington's disease

Huntington's disease is a progressive neurodegenerative disease caused by mutation of the huntingtin (HTT) gene. The identification of mutation carriers before symptom onset provides an opportunity to intervene in the early stage of the disease course. Optimal biomarkers are of great value to reflect neuropathological and clinical progression and are sensitive to potential disease-modifying treatments. Blood-based biomarkers have the merits of minimal invasiveness, low cost, easy accessibility and safety. In this review, we summarized the updated development of blood-based biomarkers for HD from six aspects, including neuronal injuries, oxidative stress, endocrine functions, immune reactions, metabolism and differentially expressed miRNAs. The blood-based biomarkers presented and discussed in this review were close to clinical applicability and might facilitate clinical design as surrogate endpoints. Exploration and validation of robust blood-based biomarkers require further standard and systemic study design in the future.

An Overview of Specialist Services for Huntington's Disease in the United Kingdom

BACKGROUND

Huntington's disease (HD) is a rare inherited neurodegenerative disorder characterized by complex evolving needs that change as the condition progresses. There is limited understanding about the organization of HD clinical services and their resourcing in the United Kingdom (UK).

OBJECTIVE

To understand the organization and resourcing of specialist HD services for people with HD (PwHD) in the UKMethods:This cross-sectional study collected quantitative data via on online survey, and qualitative data via telephone semi-structured interviews. Descriptive statistics were used to describe quantitative outcomes, and qualitative results were analyzed using content analysis.

RESULTS

A total of 31 specialist services for HD were identified. Of the 27 services that completed the online survey, 23 had an active multidisciplinary team of healthcare professionals (HCPs) and were led primarily by a mental health trust (26%) or tertiary referral hospital (26%). Specialist services offered outpatient clinics (96%), outreach in the community (74%), telemedicine (70%), inpatient beds (26%) and satellite clinics (26%). Many services indicated that their capacity (ability to see patients as often as needed with current resources) was difficult, with some services reporting more difficulty at the early or later stages of HD. Key resourcing gaps were identified with access to facilities, HCPs and referral networks.

CONCLUSIONS

This research highlights the variation in organization and capacity within individual HD services as well as current resourcing and gaps in access that influence this capacity. Further research should be done to understand the impact of service organization and current resourcing gaps in access on the quality of care provided for PwHD in the UK.

An Overview of Specialist Services for Huntington's Disease in the United Kingdom

BACKGROUND

Huntington's disease (HD) is a rare inherited neurodegenerative disorder characterized by complex evolving needs that change as the condition progresses. There is limited understanding about the organization of HD clinical services and their resourcing in the United Kingdom (UK).

OBJECTIVE

To understand the organization and resourcing of specialist HD services for people with HD (PwHD) in the UKMethods:This cross-sectional study collected quantitative data via on online survey, and qualitative data via telephone semi-structured interviews. Descriptive statistics were used to describe quantitative outcomes, and qualitative results were analyzed using content analysis.

RESULTS

A total of 31 specialist services for HD were identified. Of the 27 services that completed the online survey, 23 had an active multidisciplinary team of healthcare professionals (HCPs) and were led primarily by a mental health trust (26%) or tertiary referral hospital (26%). Specialist services offered outpatient clinics (96%), outreach in the community (74%), telemedicine (70%), inpatient beds (26%) and satellite clinics (26%). Many services indicated that their capacity (ability to see patients as often as needed with current resources) was difficult, with some services reporting more difficulty at the early or later stages of HD. Key resourcing gaps were identified with access to facilities, HCPs and referral networks.

CONCLUSIONS

This research highlights the variation in organization and capacity within individual HD services as well as current resourcing and gaps in access that influence this capacity. Further research should be done to understand the impact of service organization and current resourcing gaps in access on the quality of care provided for PwHD in the UK.

HSF1 and Its Role in Huntington's Disease Pathology

PURPOSE OF REVIEW

Heat shock factor 1 (HSF1) is the master transcriptional regulator of the heat shock response (HSR) in mammalian cells and is a critical element in maintaining protein homeostasis. HSF1 functions at the center of many physiological processes like embryogenesis, metabolism, immune response, aging, cancer, and neurodegeneration. However, the mechanisms that allow HSF1 to control these different biological and pathophysiological processes are not fully understood. This review focuses on Huntington's disease (HD), a neurodegenerative disease characterized by severe protein aggregation of the huntingtin (HTT) protein. The aggregation of HTT, in turn, leads to a halt in the function of HSF1. Understanding the pathways that regulate HSF1 in different contexts like HD may hold the key to understanding the pathomechanisms underlying other proteinopathies. We provide the most current information on HSF1 structure, function, and regulation, emphasizing HD, and discussing its potential as a biological target for therapy.

DATA SOURCES

We performed PubMed search to find established and recent reports in HSF1, heat shock proteins (Hsp), HD, Hsp inhibitors, HSF1 activators, and HSF1 in aging, inflammation, cancer, brain development, mitochondria, synaptic plasticity, polyglutamine (polyQ) diseases, and HD.

STUDY SELECTIONS

Research and review articles that described the mechanisms of action of HSF1 were selected based on terms used in PubMed search.

RESULTS

HSF1 plays a crucial role in the progression of HD and other protein-misfolding related neurodegenerative diseases. Different animal models of HD, as well as postmortem brains of patients with HD, reveal a connection between the levels of HSF1 and HSF1 dysfunction to mutant HTT (mHTT)-induced toxicity and protein aggregation, dysregulation of the ubiquitin-proteasome system (UPS), oxidative stress, mitochondrial dysfunction, and disruption of the structural and functional integrity of synaptic connections, which eventually leads to neuronal loss. These features are shared with other neurodegenerative diseases (NDs). Currently, several inhibitors against negative regulators of HSF1, as well as HSF1 activators, are developed and hold promise to prevent neurodegeneration in HD and other NDs.

CONCLUSION

Understanding the role of HSF1 during protein aggregation and neurodegeneration in HD may help to develop therapeutic strategies that could be effective across different NDs.

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.

The Chinese Version of UHDRS in Huntington's Disease: Reliability and Validity Assessment

BACKGROUND

The Unified Huntington's Disease Rating Scale (UHDRS) is a universal scale assessing disease severity of Huntington's disease (HD). However, the English version cannot be widely used in China, and the reliability and validity of the Chinese UHDRS have not yet been confirmed.

OBJECTIVE

To test the reliability and validity of Chinse UHDRS in patients with HD.

METHODS

Between August 2013 and August 2021, 159 HD patients, 40 premanifest HD, and 64 healthy controls were consecutively recruited from two medical centers in China and assessed by Chinese UHDRS. Internal consistency and interrater reliability of the scale were examined. Intercorrelation was performed to analyze the convergent and divergent validity of the scale. A receiver operating characteristic analysis was conducted to explore the optimal cutoff point of each cognitive test.

RESULTS

High internal consistency was found in Chinese UHDRS, and its Cronbach's alpha values of the motor, cognitive, behavioral and functional subscales were 0.954, 0.826, 0.804, and 0.954, respectively. The interrater reliability of the total motor score was 0.960. The convergent and divergent validity revealed that motor, cognitive and functional subscales strongly related to each other except for Problem Behavior Assessment. Furthermore, we not only provided the normal level of each cognitive test in controls, but also gave the optimal cutoff points of cognitive tests between controls and HD patients.

CONCLUSION

We demonstrate for the first time that the translated version of UHDRS is reliable for assessing HD patients in China. This can promote the universal use of UHDRS in clinical practice.

Nrf2 Pathway in Huntington's Disease (HD): What Is Its Role?

Huntington's disease (HD) is an autosomal dominant neurodegenerative disease that occurs worldwide. Despite some progress in understanding the onset of HD, drugs that block or delay symptoms are still not available. In recent years, many treatments have been proposed; among them, nuclear transcriptional factor-2 (Nrf2) enhancer compounds have been proposed as potential therapeutic agents to treat HD. Nrf2 triggers an endogenous antioxidant pathway activated in different neurodegenerative disorders. Probably, the stimulation of Nrf2 during either the early phase or before HD symptoms' onset, could slow or prevent striatum degeneration. In this review, we present the scientific literature supporting the role of Nrf2 in HD and the potential prophylactic and therapeutic role of this compound.

Prevalence and Incidence of Huntington's Disease: An Updated Systematic Review and Meta-Analysis

The incidence and prevalence of Huntington's disease (HD) based on a systematic review and meta-analysis of 20 studies published from 1985 to 2010 was estimated at 0.38 per 100,000 person-years (95% confidence interval [CI], 0.16-0.94) and 2.71 per 100,000 persons (95% CI, 1.55-4.72), respectively. Since 2010, there have been many new epidemiological studies of HD. We sought to update the global estimates of HD incidence and prevalence using data published up to February 2022 and perform additional analyses based on study continent. Medline and Embase were searched for epidemiological studies of HD published between 2010 and 2022. Risk of bias was assessed using a quality assessment tool. Estimated pooled prevalence or incidence was calculated using a random-effects meta-analysis. A total of 33 studies published between 2010 and 2022 were included. Pooled incidence was 0.48 cases per 100,000 person-years (95% CI, 0.33-0.63). Subgroup analysis by continent demonstrated a significantly higher incidence of HD in Europe and North America than in Asia. Pooled prevalence was 4.88 per 100,000 (95% CI, 3.38-7.06). Subanalyses by continent demonstrated that the prevalence of HD was significantly higher in Europe and North America than in Africa. The minor increase in prevalence (more so than incidence) demonstrated in this updated review could relate to the enhanced availability of molecular testing, earlier diagnosis, increased life expectancy, and de novo mutations. Limitations include variable case ascertainment methods and lacking case validation data. © 2022 Her Majesty the Queen in Right of Canada. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society. Reproduced with the permission of the Minister of Public Health Agency of Canada.

A Novel Huntington's Disease Assessment Platform to Support Future Drug Discovery and Development

Huntington's disease (HD) is a lethal neurodegenerative disorder without efficient therapeutic options. The inefficient translation from preclinical and clinical research into clinical use is mainly attributed to the lack of (i) understanding of disease initiation, progression, and involved molecular mechanisms; (ii) knowledge of the possible HD target space and general data awareness; (iii) detailed characterizations of available disease models; (iv) better suitable models; and (v) reliable and sensitive biomarkers. To generate robust HD-like symptoms in a mouse model, the neomycin resistance cassette was excised from zQ175 mice, generating a new line: zQ175^Δneo. We entirely describe the dynamics of behavioral, neuropathological, and immunohistological changes from 15-57 weeks of age. Specifically, zQ175^Δneo mice showed early astrogliosis from 15 weeks; growth retardation, body weight loss, and anxiety-like behaviors from 29 weeks; motor deficits and reduced muscular strength from 36 weeks; and finally slight microgliosis at 57 weeks of age. Additionally, we collected the entire bioactivity network of small-molecule HD modulators in a multitarget dataset (HD_MDS). Hereby, we uncovered 358 unique compounds addressing over 80 different pharmacological targets and pathways. Our data will support future drug discovery approaches and may serve as useful assessment platform for drug discovery and development against HD.

Current Diagnostic Methods and Non-Coding RNAs as Possible Biomarkers in Huntington's Disease

Whether as a cause or a symptom, RNA transcription is recurrently altered in pathologic conditions. This is also true for non-coding RNAs, with regulatory functions in a variety of processes such as differentiation, cell identity and metabolism. In line with their increasingly recognized roles in cellular pathways, RNAs are also currently evaluated as possible disease biomarkers. They could be informative not only to follow disease progression and assess treatment efficacy in clinics, but also to aid in the development of new therapeutic approaches. This is especially important for neurological and genetic disorders, where the administration of appropriate treatment during the disease prodromal stage could significantly delay, if not halt, disease progression. In this review we focus on the current status of biomarkers in Huntington's Disease (HD), a fatal hereditary and degenerative disease condition. First, we revise the sources and type of wet biomarkers currently in use. Then, we explore the feasibility of different RNA types (miRNA, ncRNA, circRNA) as possible biomarker candidates, discussing potential advantages, disadvantages, sources of origin and the ongoing investigations on this topic.

Neuroprotective effect of silymarin against 3-Nitropropionic acid-induced neurotoxicity in rats

(HD) Huntington's disease is a severe hereditary catastrophic neurological disease with an autosomal dominant heritable changes manifested by cognitive, behavioural, and motor progression deficits, resulting in death. Several mechanisms are involved in the pathogenesis of this complex and rare disease, including excitotoxicity, mitochondrial dysfunction, neurotransmitters imbalance, and oxidative stress. Silymarin was selected as an investigational drug, due to its numerous activities in current research, it possesses substantial antioxidant and neuroprotective functionalities. The present research attempts, i.p. injections of 3-NPA (10 ​mg/kg) were given for 21 days to trigger Huntington-like symptoms in rats. The percentage fluctuations in body weight, the footfall counts, and the time required to transverse the beam and motor functions were analyzed at multiple time points. Oxidative stress markers like MDA/LPO, GSH, protein, nitrite, catalase, and superoxide dismutase levels were examined in the striatum region. The current study results conclusively demonstrate that chronic 3-NPA administration significantly decreased the body weight and showed marked abnormalities in motor coordination, locomotion, and increased striatal generation of free radicals. Furthermore, treatment with silymarin (100 & 200 ​mg/kg/p.o.), mitigated 3-NPA triggered behavioural and biochemical alterations. Our study results could conclude that Silymarin may be advantageous and might develop an adjuvant treatment for the management of Huntington's disease.

Inflammasome activation and assembly in Huntington's disease

Huntington's disease (HD) is a rare neurodegenerative disease characterized by motor, cognitive, and psychiatric symptoms. Inflammasomes are multiprotein complexes capable of sensing pathogen-associated and damage-associated molecular patterns, triggering innate immune pathways. Activation of inflammasomes results in a pro-inflammatory cascade involving, among other molecules, caspases and interleukins. NLRP3 (nucleotide-binding domain, leucine-rich-repeat containing family, pyrin domain-containing 3) is the most studied inflammasome complex, and its activation results in caspase-1 mediated cleavage of the pro-interleukins IL-1β and IL-18 into their mature forms, also inducing a gasdermin D mediated form of pro-inflammatory cell death, i.e. pyroptosis. Accumulating evidence has implicated NLRP3 inflammasome complex in neurodegenerative diseases. The evidence in HD is still scant and mostly derived from pre-clinical studies. This review aims to present the available evidence on NLRP3 inflammasome activation in HD and to discuss whether targeting this innate immune system complex might be a promising therapeutic strategy to alleviate its symptoms.

Multiview behavior and neurotransmitter analysis of zebrafish dyskinesia induced by 6PPD and its metabolites

The typical tire manufacturing additive 6PPD, its metabolites 6PPDQ and 4-Hydroxy should be monitored because of their ubiquitous presence in the environment and the high toxicity of 6PPDQ to coho salmon. The toxic effect of 6PPD and its metabolites have been revealed superficially, especially on behavioral characteristics. However, the behavioral indicators explored so far are relatively simple and the toxic causes are poorly understood. With this in mind, our work investigated the toxic effects of 6PPD, 6PPDQ and 4-Hydroxy on adult zebrafish penetratingly through machine vision, and the meandering, body angle, top time and 3D trajectory are used for the first time to show the abnormal behaviors induced by 6PPD and its metabolites. Moreover, neurotransmitter changes in the zebrafish brain were measured to explore the causes of abnormal behavior. The results showed that high-dose treatment of 6PPD reduced the velocity by 42.4% and decreased the time at the top of the tank by 91.0%, suggesting significant activity inhibition and anxiety. In addition, γ-aminobutyric acid and acetylcholine were significantly impacted by 6PPD, while dopamine exhibited a slight variation, which can explain the bradykinesia, unbalance and anxiety of zebrafish and presented similar symptoms as Huntingdon's disease. Our study explored new abnormal behaviors of zebrafish induced by 6PPD and its metabolites in detail, and the toxic causes were revealed for the first time by studying the changes of neurotransmitters, thus providing an important reference for further studies of the biological toxicity of 6PPD and its metabolites.

Petri net transition times as training features for multiclass models to support the detection of neurodegenerative diseases

This paper proposes the transition times of Petri net models of human gait as training features for multiclass random forests (RFs) and classification trees (CTs). These models are designed to support screening for neurodegenerative diseases. The proposed Petri net describes gait in terms of nine cyclic phases and the timing of the nine events that mark the transition between phases. Since the transition times between strides vary, each is represented as a random variable characterized by its mean and standard deviation. These transition times are calculated using the PhysioNet database of vertical ground reaction forces (VGRFs) generated by feet-ground contact. This database comprises the VGRFs of four groups: amyotrophic lateral sclerosis, the control group, Huntington's disease, and Parkinson disease. The RF produced an overall classification accuracy of 91%, and the specificities and sensitivities for each class were between 80% and 100%. However, despite this high performance, the RF-generated models demonstrated lack of interpretability prompted the training of a CT using identical features. The obtained tree comprised only four features and required a maximum of three comparisons. However, this simplification dramatically reduced the overall accuracy from 90.6% to 62.3%. The proposed set features were compared with those included in PhysioNet database of VGRFs. In terms of both the RF and CT, more accurate models were established using our features than those of the PhysioNet.

Spermatozoan Metabolism as a Non-Traditional Model for the Study of Huntington’s Disease

Huntington’s Disease (HD) is a fatal autosomal dominant neurodegenerative disease manifested through motor dysfunction and cognitive deficits. Decreased fertility is also observed in HD animal models and HD male patients, due to altered spermatogenesis and sperm function, thus resulting in reduced fertilization potential. Although some pharmaceuticals are currently utilized to mitigate HD symptoms, an effective treatment that remedies the pathogenesis of the disease is yet to be approved by the FDA. Identification of genes and relevant diagnostic biomarkers and therapeutic target pathways including glycolysis and mitochondrial complex-I-dependent respiration may be advantageous for early diagnosis, management, and treatment of the disease. This review addresses the HD pathway in neuronal and sperm metabolism, including relevant gene and protein expression in both neurons and spermatozoa, indicated in the pathogenesis of HD. Furthermore, zinc-containing and zinc-interacting proteins regulate and/or are regulated by zinc ion homeostasis in both neurons and spermatozoa. Therefore, this review also aims to explore the comparative role of zinc in both neuronal and sperm function. Ongoing studies aim to characterize the products of genes implicated in HD pathogenesis that are expressed in both neurons and spermatozoa to facilitate studies of future treatment avenues in HD and HD-related male infertility. The emerging link between zinc homeostasis and the HD pathway could lead to new treatments and diagnostic methods linking genetic sperm defects with somatic comorbidities.

Adeno-Associated Viruses for Modeling Neurological Diseases in Animals: Achievements and Prospects

Adeno-associated virus (AAV) vectors have become an attractive tool for efficient gene transfer into animal tissues. Extensively studied as the vehicles for therapeutic constructs in gene therapy, AAVs are also applied for creating animal models of human genetic disorders. Neurological disorders are challenging to model in laboratory animals by transgenesis or genome editing, at least partially due to the embryonic lethality and the timing of the disease onset. Therefore, gene transfer with AAV vectors provides a more flexible option for simulating genetic neurological disorders. Indeed, the design of the AAV expression construct allows the reproduction of various disease-causing mutations, and also drives neuron-specific expression. The natural and newly created AAV serotypes combined with various delivery routes enable differentially targeting neuronal cell types and brain areas in vivo. Moreover, the same viral vector can be used to reproduce the main features of the disorder in mice, rats, and large laboratory animals such as non-human primates. The current review demonstrates the general principles for the development and use of AAVs in modeling neurological diseases. The latest achievements in AAV-mediated modeling of the common (e.g., Alzheimer’s disease, Parkinson’s disease, ataxias, etc.) and ultra-rare disorders affecting the central nervous system are described. The use of AAVs to create multiple animal models of neurological disorders opens opportunities for studying their mechanisms, understanding the main pathological features, and testing therapeutic approaches.

Natural History and Burden of Huntington's Disease in the UK: A Population-Based Cohort Study

BACKGROUND

Huntington's disease (HD) is a rare neurodegenerative disease that presents with progressive psychological, cognitive and motor impairment. These diverse symptoms place a high burden on the patient, families and the healthcare systems they rely on. This study aimed to describe the epidemiology and clinical burden in individuals with HD compared with controls from the general population.

METHODS

This cohort study utilised data from general practitioner (GP) medical records to estimate the prevalence and incidence of HD between Jan 2000 and Dec 2018. A cohort of incident HD cases were matched 1:3 to controls from the general population, in whom common clinical diagnoses, medications and healthcare interventions were compared at the time of first recorded diagnosis and at a time close to death. Incidence rates of common diagnoses and mortality were compared with matched controls in the time following HD diagnosis.

RESULTS

Prevalence of HD increased between 2000 and 2018, whilst incidence remained stable. Prevalence of psychiatric diagnoses and symptomatic treatments were higher in HD cases than controls. A higher relative risk of psychotic disorders, depression, insomnia, dementia, weight loss, pneumonia and falls was observed in HD cases. Risk of death was >4 times higher in HD, with a median survival of ~12 years from first recorded diagnosis.

CONCLUSIONS

This study demonstrates the significant and progressive clinical burden in individuals up to 18 years after first recorded diagnosis.

MicroRNA Alteration, Application as Biomarkers, and Therapeutic Approaches in Neurodegenerative Diseases

MicroRNAs (miRNAs) are essential post-transcriptional gene regulators involved in various neuronal and non-neuronal cell functions and play a key role in pathological conditions. Numerous studies have demonstrated that miRNAs are dysregulated in major neurodegenerative diseases, such as Alzheimer’s disease, Parkinson’s disease, multiple sclerosis, amyotrophic lateral sclerosis, or Huntington’s disease. Hence, in the present work, we constructed a comprehensive overview of individual microRNA alterations in various models of the above neurodegenerative diseases. We also provided evidence of miRNAs as promising biomarkers for prognostic and diagnostic approaches. In addition, we summarized data from the literature about miRNA-based therapeutic applications via inhibiting or promoting miRNA expression. We finally identified the overlapping miRNA signature across the diseases, including miR-128, miR-140-5p, miR-206, miR-326, and miR-155, associated with multiple etiological cellular mechanisms. However, it remains to be established whether and to what extent miRNA-based therapies could be safely exploited in the future as effective symptomatic or disease-modifying approaches in the different human neurodegenerative disorders.

Insights into Human-Induced Pluripotent Stem Cell-Derived Astrocytes in Neurodegenerative Disorders

Most neurodegenerative disorders have complex and still unresolved pathology characterized by progressive neuronal damage and death. Astrocytes, the most-abundant non-neuronal cell population in the central nervous system, play a vital role in these processes. They are involved in various functions in the brain, such as the regulation of synapse formation, neuroinflammation, and lactate and glutamate levels. The development of human-induced pluripotent stem cells (iPSCs) reformed the research in neurodegenerative disorders allowing for the generation of disease-relevant neuronal and non-neuronal cell types that can help in disease modeling, drug screening, and, possibly, cell transplantation strategies. In the last 14 years, the differentiation of human iPSCs into astrocytes allowed for the opportunity to explore the contribution of astrocytes to neurodegenerative diseases. This review discusses the development protocols and applications of human iPSC-derived astrocytes in the most common neurodegenerative conditions.

Montreal cognitive assessment for evaluating cognitive impairment in Huntington's disease: a systematic review

OBJECTIVE

This study aims to systematically review evidence of the accuracy of the Montreal Cognitive Assessment (MoCA) for evaluating the presence of cognitive impairment in patients with Huntington's disease (HD) and to outline the quality and quantity of research evidence available about the use of the MoCA in this population.

METHODS

We conducted a systematic literature review, searching four databases from inception until April 2020.

RESULTS

We identified 26 studies that met the inclusion criteria: two case-control studies comparing the MoCA to a battery of tests, three studies comparing MoCA to Mini-Mental State Examination, two studies estimating the prevalence of cognitive impairment in individuals with HD and 19 studies or clinical trials in which the MoCA was used as an instrument for the cognitive assessment of participants with HD. We found no cross-sectional studies in which participants received the index test (MoCA) and a reference standard diagnostic assessment composed of an extensive neuropsychological battery. The publication period ranged from 2010 to 2020.

CONCLUSIONS

In patients with HD, the MoCA provides information about disturbances in general cognitive function. Even if the MoCA demonstrated good sensitivity and specificity when used at the recommended threshold score of 26, further cross-sectional studies are required to examine the optimum cutoff score for detecting cognitive impairments in patients with HD. Moreover, more studies are necessary to determine whether the MoCA adequately assesses cognitive status in individuals with HD.

More than Just a Brain Disorder: A Five-Point Manifesto for Psychological Care for People with Huntington’s Disease

Huntington’s disease (HD) is a rare and complex condition where affected individuals, family members, caregivers, and clinicians face a number of both long-term and fluctuating challenges. The predominant biomedical framework adopted in HD to date has traditionally viewed it as a brain disorder first and foremost. As a consequence, one of the most challenging aspects of the condition—psychological difficulties and their care—is often not given the emphasis it deserves in everyday clinical practice. Here, we propose a manifesto outlining five points to address the quality, effectiveness, availability, and accessibility of psychological care in HD. These include (1) Listening to People with HD, (2) Reformulating Difficulties Psychologically, (3) Exploring New Interventions, (4) Increasing Psychological Provision, and (5) Learning from Other Conditions. As the search for a cure continues, we hope that this manifesto will create a new impetus towards refining the current approach to psychological difficulties in HD and ultimately improve the quality of life of the tens of thousands of families affected by HD worldwide.

Healthcare resource utilization and costs in individuals with Huntington's disease by disease stage in a US population

AIMS

To quantify healthcare resource utilization (HRU) and costs by disease stage in individuals with Huntington's disease (HD) in a US population.

MATERIALS AND METHODS

This retrospective cohort study used administrative claims data from the IBM MarketScan Commercial, Multi-State Medicaid, and Medicare Supplemental Databases between 1 January 2009 and 31 December 2018. Individuals with an HD claim between 1 January 2010 and 31 December 2017 were selected. Index date was the date of first HD diagnosis. Individuals were required to have continuous enrollment for ≥ 12 months pre-index, 3 months post-index, and have no pre-index HD claims. All-cause HRU and costs per patient per month (PPPM) (overall and stratified by disease stage) were assessed for individuals with HD.

RESULTS

A total of 2,669 individuals with HD were identified. Of these, 1,432 (53.7%), 689 (25.8%), and 548 (20.5%) had early-, middle-, and late-stage HD at baseline, respectively. Mean HRU PPPM by post-index HD stage increased with disease stage for outpatient visits, pharmacy claims, and HD-related pharmacy claims (p < 0.05 for all). Mean inpatient visits and emergency room visits PPPM were highest in individuals with middle-stage HD (p <0.05 for all). Mean total all-cause healthcare cost PPPM for individuals with HD was $2,889, and it was significantly higher in middle-stage individuals, at $7,988, compared with early- and late-stage individuals, at $3,726 and $5,125, respectively; p <0.0001.

LIMITATIONS

In the absence of disease staging information in administrative claims data, staging was based on the presence of clinical markers in claims. Our evaluations didn't include the indirect costs of HD, which may be substantial as HD typically affects people at their peak earning potential.

CONCLUSIONS

HRU and costs of care are high among individuals with HD, particularly among those with middle- and late-stage disease. This indicates that the disease burden in HD increases with disease stage, highlighting the need for interventions that can slow or prevent disease progression.