The global prevalence of Huntington's disease: a systematic review and discussion

Exploring Place of Death among Individuals with Huntington's Disease in the United States

OBJECTIVES

To describe trends and identify factors associated with place of death among individuals with Huntington's disease (HD).

DESIGN

Retrospective cohort of deceased individuals with HD from the Centers for Disease Control and Prevention's National Center for Health Statistics.

SETTING AND PARTICIPANTS

A total of 13,350 individuals with HD who died in the United States between 2009 and 2019.

METHODS

We analyzed place of death, categorized as long-term care (LTC) facility, home, hospital, hospice facility, and other locations. Trends in the places of death from 2009 to 2019 were assessed using linear regression models. Multivariate logistic regression models were used to identify sociodemographic factors associated with place of death.

RESULTS

From 2009 to 2019, the greatest proportion of deaths occurred in LTC facilities (48.4%). There was a significantly decreasing trend in the proportion of deaths occurring in LTC facilities (53.5%-43.9%, P < .001). A greater proportion of deaths in rural areas occurred in LTC facilities compared with all other locations (P < .001 for all comparisons). In the multivariate model, aged younger than 44 years, Black race, Hispanic ethnicity, some college education or greater, and being married were associated with significantly lower odds of dying in a LTC facility compared with home.

CONCLUSIONS AND IMPLICATIONS

Despite a decreasing trend, LTC facilities remain a cornerstone of support for individuals with HD, particularly in rural areas. These results suggest multiple avenues for research to improve accessibility and quality of care for individuals with late stages of HD. Future studies are needed to further understand the impact of rurality and lack of support in the home on the accessibility and quality of LTC and hospice care for individuals with HD. These results may also help inform interventions focused on training and staff education within LTC and hospice facilities to better manage HD progression and symptoms.

Parthenolide ameliorates 3-nitropropionic acid-induced Huntington's disease-like aberrations via modulating NLRP3 inflammasome, reducing microglial activation and inducing astrocyte shifting

BACKGROUND

Huntington's disease (HD) is a progressive neurodegenerative disease that causes motor, cognitive, and psychiatric abnormalities, with no satisfying disease-modifying therapy so far. 3-nitropropionic acid (3NP) induces behavioural deficits, together with biochemical and histological alterations in animals' striata that mimic HD. The role of nucleotide-binding domain, leucine-rich-containing family, pyrin domain-containing-3 (NLRP3) inflammasome in HD pathogenesis remains largely uncharacterized. Parthenolide (PTL), a naturally occurring nuclear factor kappa B (NF-κB) inhibitor, is also known to inhibit NLRP3 inflammasome. Whether PTL is beneficial in HD has not been established yet.

AIM

This study evaluated the possible neuroprotective effects of PTL against 3NP-induced behavioural abnormalities, striatal biochemical derangements, and histological aberrations.

METHODS

Male Wistar rats received PTL (0.5 mg/kg/day, i.p) for 3 weeks and 3NP (10 mg/kg/day, i.p) was administered alongside for the latter 2 weeks to induce HD. Finally, animals were subjected to open-field, Morris water maze and rotarod tests. Rat striata were examined histologically, striatal protein expression levels of glial fibrillary acidic protein (GFAP), cluster of differentiation 45 (CD45) and neuron-specific enolase (NSE) were evaluated immunohistochemically, while those of interleukin (IL)-1β, IL-18, ionized calcium-binding adapter molecule-1 (Iba1) and glutamate were determined by ELISA. Striatal nuclear factor erythroid 2-related factor 2 (Nrf2), Kelch-like ECH-associated protein (Keap1), NF-κB, NLRP3, apoptosis-associated speck-like protein containing a CARD (ASC), caspase-1, S100 calcium-binding protein A10 (S100A10) and complement-3 (C3) were assessed by gene expression analysis.

RESULTS

PTL improved motor, locomotor, cognitive and anxiety-like behaviours, restored neuronal integrity, upregulated Nrf2, and inhibited NLRP3 inflammasome, NF-κB and microglial activation. Additionally, PTL induced astrocyte shifting towards the neuroprotective A2 phenotype.

CONCLUSION

PTL exhibits neuroprotection against 3NP-induced HD, that might be ascribed, at least in part, to its modulatory effects on Keap1/Nrf2 and NF-κB/NLRP3 inflammasome signaling.

Identification of molecular targets and small drug candidates for Huntington's disease via bioinformatics and a network-based screening approach

Huntington's disease (HD) is a gradually severe neurodegenerative ailment characterised by an increase of a specific trinucleotide repeat sequence (cytosine-adenine-guanine, CAG). It is passed down as a dominant characteristic that worsens over time, creating a significant risk. Despite being monogenetic, the underlying mechanisms as well as biomarkers remain poorly understood. Furthermore, early detection of HD is challenging, and the available diagnostic procedures have low precision and accuracy. The research was conducted to provide knowledge of the biomarkers, pathways and therapeutic targets involved in the molecular processes of HD using informatic based analysis and applying network-based systems biology approaches. The gene expression profile datasets GSE97100 and GSE74201 relevant to HD were studied. As a consequence, 46 differentially expressed genes (DEGs) were identified. 10 hub genes (TPM1, EIF2S3, CCN2, ACTN1, ACTG2, CCN1, CSRP1, EIF1AX, BEX2 and TCEAL5) were further differentiated in the protein-protein interaction (PPI) network. These hub genes were typically down-regulated. Additionally, DEGs-transcription factors (TFs) connections (e.g. GATA2, YY1 and FOXC1), DEG-microRNA (miRNA) interactions (e.g. hsa-miR-124-3p and has-miR-26b-5p) were also comprehensively forecast. Additionally, related gene ontology concepts (e.g. sequence-specific DNA binding and TF activity) connected to DEGs in HD were identified using gene set enrichment analysis (GSEA). Finally, in silico drug design was employed to find candidate drugs for the treatment HD, and while the possible modest therapeutic compounds (e.g. cortistatin A, 13,16-Epoxy-25-hydroxy-17-cheilanthen-19,25-olide, Hecogenin) against HD were expected. Consequently, the results from this study may give researchers useful resources for the experimental validation of Huntington's diagnosis and therapeutic approaches.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Exploring molecular mechanisms, therapeutic strategies, and clinical manifestations of Huntington's disease

Huntington's disease (HD) is a paradigm of a genetic neurodegenerative disorder characterized by the expansion of CAG repeats in the HTT gene. This extensive review investigates the molecular complexities of HD by highlighting the pathogenic mechanisms initiated by the mutant huntingtin protein. Adverse outcomes of HD include mitochondrial dysfunction, compromised protein clearance, and disruption of intracellular signaling, consequently contributing to the gradual deterioration of neurons. Numerous therapeutic strategies, particularly precision medicine, are currently used for HD management. Antisense oligonucleotides, such as Tominersen, play a leading role in targeting and modulating the expression of mutant huntingtin. Despite the promise of these therapies, challenges persist, particularly in improving delivery systems and the necessity for long-term safety assessments. Considering the future landscape, the review delineates promising directions for HD research and treatment. Innovations such as Clustered regularly interspaced short palindromic repeats associated system therapies (CRISPR)-based genome editing and emerging neuroprotective approaches present unprecedented opportunities for intervention. Collaborative interdisciplinary endeavors and a more insightful understanding of HD pathogenesis are on the verge of reshaping the therapeutic landscape. As we navigate the intricate landscape of HD, this review serves as a guide for unraveling the intricacies of this disease and progressing toward transformative treatments.

Underestimated olfactory domains in Huntington's disease: odour discrimination and threshold

BACKGROUND

Olfaction has recently found clinical value in prediction, discrimination and prognosis of some neurodegenerative disorders. However, data originating from standard tests on olfactory dysfunction in Huntington's disease are limited to odour identification, which is only one domain of olfactory perceptual space.

METHOD

Twenty-five patients and 25 age- and gender-matched controls were evaluated by the Sniffin' Sticks test in three domains of odour threshold, odour discrimination, odour identification and the sum score of them. Patients' motor function was assessed based on the Unified Huntington's Disease Rating Scale.

RESULTS

Compared with controls, patients' scores of all olfactory domains and their sum were significantly lower. Besides, our patients' odour threshold and odour discrimination impairments were more frequently impaired than odour identification impairment (86 per cent and 81 per cent vs 34 per cent, respectively).

CONCLUSION

Olfactory impairment is a common finding in patients with Huntington's disease; it is not limited to odour identification but is more pronounced in odour discrimination and odour threshold.

Prevalence of Juvenile-Onset and Pediatric Huntington's Disease and Their Availability and Ability to Participate in Trials: A Dutch Population and Enroll-HD Observational Study

Background

Juvenile-onset Huntington's disease (JHD) represents 1-5% of Huntington's disease (HD) patients, with onset before the age of 21. Pediatric HD (PHD) relates to a proportion of JHD patients that is still under 18 years of age. So far, both populations have been excluded from interventional trials.

Objective

Describe the prevalence and incidence of JHD and PHD in the Netherlands and explore their ability to participate in interventional trials.

Methods

The prevalence and incidence of PHD and JHD patients in the Netherlands were analyzed. In addition, we explored proportions of JHD patients diagnosed at pediatric versus adult age, their diagnostic delay, and functional and modelled (CAP100) disease stage in JHD and adult-onset HD patients at diagnosis.

Results

The prevalence of JHD and PHD relative to the total manifest HD population in January 2024 was between 0.84-1.25% and 0.09-0.14% respectively. The mean incidence of JHD patients being diagnosed was between 0.85-1.28 per 1000 patient years and of PHD 0.14 per 1.000.000 under-aged person years. 55% of JHD cases received a clinical diagnosis on adult age. At diagnosis, the majority of JHD patients was functionally compromised and adolescent-onset JHD patients were significantly less independent compared to adult-onset HD patients.

Conclusions

In the Netherlands, the epidemiology of JHD and PHD is lower than previously suggested. More than half of JHD cases are not eligible for trials in the PHD population. Furthermore, higher functional dependency in JHD patients influences their ability to participate in trials. Lastly, certain UHDRS functional assessments and the CAP100 score do not seem appropriate for this particular group.

A Comprehensive Bioinformatics Approach to Identify Molecular Signatures and Key Pathways for the Huntington Disease

Huntington disease (HD) is a degenerative brain disease caused by the expansion of CAG (cytosine-adenine-guanine) repeats, which is inherited as a dominant trait and progressively worsens over time possessing threat. Although HD is monogenetic, the specific pathophysiology and biomarkers are yet unknown specifically, also, complex to diagnose at an early stage, and identification is restricted in accuracy and precision. This study combined bioinformatics analysis and network-based system biology approaches to discover the biomarker, pathways, and drug targets related to molecular mechanism of HD etiology. The gene expression profile data sets GSE64810 and GSE95343 were analyzed to predict the molecular markers in HD where 162 mutual differentially expressed genes (DEGs) were detected. Ten hub genes among them (DUSP1, NKX2-5, GLI1, KLF4, SCNN1B, NPHS1, SGK2, PITX2, S100A4, and MSX1) were identified from protein-protein interaction (PPI) network which were mostly expressed as down-regulated. Following that, transcription factors (TFs)-DEGs interactions (FOXC1, GATA2, etc), TF-microRNA (miRNA) interactions (hsa-miR-340, hsa-miR-34a, etc), protein-drug interactions, and disorders associated with DEGs were predicted. Furthermore, we used gene set enrichment analysis (GSEA) to emphasize relevant gene ontology terms (eg, TF activity, sequence-specific DNA binding) linked to DEGs in HD. Disease interactions revealed the diseases that are linked to HD, and the prospective small drug molecules like cytarabine and arsenite was predicted against HD. This study reveals molecular biomarkers at the RNA and protein levels that may be beneficial to improve the understanding of molecular mechanisms, early diagnosis, as well as prospective pharmacologic targets for designing beneficial HD treatment.

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.

Pridopidine Does Not Significantly Prolong the QTc Interval at the Clinically Relevant Therapeutic Dose

INTRODUCTION

Pridopidine is a highly selective sigma-1 receptor (S1R) agonist in development for the treatment of Huntington's disease (HD) and amyotrophic lateral sclerosis (ALS). Pridopidine's activation of S1R enhances cellular processes that are crucial for neuronal function and survival but are impaired in neurodegenerative diseases. Human brain positron emission tomography (PET) imaging studies show that at the therapeutic dose of 45 mg twice daily (bid), pridopidine selectively and robustly occupies the S1R. We conducted concentration-QTc (C-QTc) analyses to assess pridopidine's effect on the QT interval and investigated its cardiac safety profile.

METHODS

C-QTc analysis was conducted using data from PRIDE-HD, a phase 2, placebo-controlled trial evaluating four pridopidine doses (45, 67.5, 90, 112.5 mg bid) or placebo over 52 weeks in HD patients. Triplicate electrocardiograms (ECGs) with simultaneous plasma drug concentrations were determined in 402 patients with HD. The effect of pridopidine on the Fridericia-corrected QT interval (QTcF) was evaluated. Cardiac-related adverse events (AEs) were analyzed from PRIDE-HD alone and from pooled safety data of three double-blind, placebo-controlled trials with pridopidine in HD (HART, MermaiHD, and PRIDE-HD).

RESULTS

A concentration-dependent effect of pridopidine on the change from baseline in the Fridericia-corrected QT interval (ΔQTcF) was observed, with a slope of 0.012 ms (ms) per ng/mL (90% confidence interval (CI), 0.0109-0.0127). At the therapeutic dose of 45 mg bid, the predicted placebo-corrected ΔQTcF (ΔΔQTcF) was 6.6 ms (upper bound 90% CI, 8.0 ms), which is below the level of concern and not clinically relevant. Analysis of pooled safety data from three HD trials demonstrates that at 45 mg bid, pridopidine cardiac-related AE frequencies are similar to those with placebo. No patients reached a QTcF of 500 ms and no patients experienced torsade de pointes (TdP) at any pridopidine dose.

CONCLUSIONS

At the 45 mg bid therapeutic dose, pridopidine demonstrates a favorable cardiac safety profile, with an effect on the QTc interval that is below the level of concern and not clinically relevant.

TRIAL REGISTRATION

PRIDE-HD (TV7820-CNS-20002) trial registration: ClinicalTrials.gov identifier, NCT02006472, EudraCT 2013-001888-23; HART (ACR16C009) trial registration: ClinicalTrials.gov identifier, NCT00724048; MermaiHD (ACR16C008) trial registration: ClinicalTrials.gov identifier, NCT00665223, EudraCT No. 2007-004988-22.

Unraveling the role of relative telomere length and CAG expansion on initial symptoms of juvenile Huntington disease

BACKGROUND AND PURPOSE

Juvenile-onset Huntington disease (JHD) is defined when symptoms initiate before 20 years of age. Mechanisms explaining differences between juvenile and adult onset are not fully understood. Our aim was to analyze the distribution of initial symptoms in a cohort of JHD patients and to explore its relationship with CAG expansion and relative telomere length (RTL).

METHODS

A total of 84 JHD patients and 54 neurologically healthy age and sex matched individuals were recruited. CAG length was measured by southern blot or triplet repeat primed polymerase chain reaction. RTL was measured using the Cawthon method.

RESULTS

Psychiatric symptoms were most frequent when considering the entire cohort. When divided into onset before or after 10 years, cognitive symptoms were more frequent in the youngest, whilst in the older group psychiatric symptoms prevailed. Motor symptoms were rare in the youngest and epilepsy was observed only in this group as well as a larger CAG expansion. RTL analysis revealed shorter telomeres in JHD patients compared to controls. This difference is not influenced by age, initial symptoms, time of disease or CAG expansion.

CONCLUSIONS

To the best of our knowledge this is the largest cohort of JHD patients reported. Psychiatric manifestations deserve special attention when JHD is suspected and epilepsy is especially important in the youngest patients. Initial symptoms seem to be influenced by CAG expansion and therefore age of onset. RTL is significantly reduced in JHD patients which can influence the characteristic neurodegeneration of JHD and contribute to the clinical discrepancy between adult and juvenile forms of Huntington disease.

Subtyping monogenic disorders: Huntington disease

Huntington disease is a highly disabling neurodegenerative disease characterized by psychiatric, cognitive, and motor deficits. The causal genetic mutation in huntingtin (Htt, also known as IT15), located on chromosome 4p16.3, leads to an expansion of a triplet coding for polyglutamine. The expansion is invariably associated with the disease when >39 repeats. Htt encodes for the protein huntingtin (HTT), which carries out many essential biological functions in the cell, in particular in the nervous system. The precise mechanism of toxicity is not known. Based on a one-gene-one-disease framework, the prevailing hypothesis ascribes toxicity to the universal aggregation of HTT. However, the aggregation process into mutant huntingtin (mHTT) is associated with a reduction of the levels of wild-type HTT. A loss of wild-type HTT may plausibly be pathogenic, contributing to the disease onset and progressive neurodegeneration. Moreover, many other biological pathways are altered in Huntington disease, such as in the autophagic system, mitochondria, and essential proteins beyond HTT, potentially explaining biological and clinical differences among affected individuals. As one gene does not mean one disease, future efforts at identifying specific Huntington subtypes are important to design biologically tailored therapeutic approaches that correct the corresponding biological pathways-rather than continuing to exclusively target the common denominator of HTT aggregation for elimination.

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.

Modulation of adenosine signaling reverses 3-nitropropionic acid-induced bradykinesia and memory impairment in adult zebrafish

Huntington's disease (HD) is a neurodegenerative disorder, characterized by motor dysfunction, psychiatric disturbance, and cognitive decline. In the early stage of HD, occurs a decrease in dopamine D₂ receptors and adenosine A_2A receptors (A_2AR), while in the late stage also occurs a decrease in dopamine D₁ receptors and adenosine A₁ receptors (A₁R). Adenosine exhibits neuromodulatory and neuroprotective effects in the brain and is involved in motor control and memory function. 3-Nitropropionic acid (3-NPA), a toxin derived from plants and fungi, may reproduce HD behavioral phenotypes and biochemical characteristics. This study investigated the effects of acute exposure to CPA (A₁R agonist), CGS 21680 (A_2AR agonist), caffeine (non-selective of A₁R and A_2AR antagonist), ZM 241385 (A_2AR antagonist), DPCPX (A₁R antagonist), dipyridamole (inhibitor of nucleoside transporters) and EHNA (inhibitor of adenosine deaminase) in an HD pharmacological model induced by 3-NPA in adult zebrafish. CPA, CGS 21680, caffeine, ZM 241385, DPCPX, dipyridamole, and EHNA were acutely administered via i.p. in zebrafish after 3-NPA (at dose 60 mg/kg) chronic treatment. Caffeine and ZM 241385 reversed the bradykinesia induced by 3-NPA, while CGS 21680 potentiated the bradykinesia caused by 3-NPA. Moreover, CPA, caffeine, ZM 241385, DPCPX, dipyridamole, and EHNA reversed the 3-NPA-induced memory impairment. Together, these data support the hypothesis that A_2AR antagonists have an essential role in modulating locomotor function, whereas the activation of A₁R and blockade of A_2AR and A₁R and modulation of adenosine levels may reduce the memory impairment, which could be a potential pharmacological strategy against late-stage symptoms HD.

Neuroprotective Potential of Hydroalcoholic Extract of Centella asiatica Against 3-Nitropropionic Acid-Induced Huntington's Like Symptoms in Adult Zebrafish

Huntington's disease (HD) is an inherited neurodegenerative disease. 3-Nitropropionic acid (3-NP) causes increased reactive oxygen species production and neuroinflammation. Centella asiatica (CA) is a strong antioxidant. The aim of this study is to investigate the effect of hydroalcoholic extract of C. asiatica (HA-CA) on 3-NP-induced HD in adult zebrafish. Adult zebrafish (∼5-6 months old) weighing 470 to 530 mg was used and treated with 3-NP (5 mg/kg intraperitoneal [i.p.]). The animals received HA-CA (80 and 100 mg/L) daily for up to 28 days in water. Tetrabenazine (3 mg/kg i.p.) was used as a standard drug. We have done an open field test (for locomotor activity), a novel tank diving test (for anxiety), and a light and dark tank test (for memory), followed by biochemical analysis (acetyl-cholinesterase [AchEs], nitrite, lipid peroxidation [LPO], and glutathione [GSH]) and histopathology to further confirm memory dysfunctions. 3-NP-treated zebrafish exhibit reductions in body weight, progressive neuronal damage, cognition, and locomotor activity. The HA-CA group significantly reduced the 3-NP-induced increase in LPO, AchEs, and nitrite levels while decreasing GSH levels. Oral administration of HA-CA (80 or 100 mg/L) significantly reduces 3-NP-induced changes in body weight and behaviors, in addition to neuroinflammation in the brain by lowering tumor necrosis factor-α and interleukin-1β levels. Moreover, HA-CA significantly decreases the 3-NP-induced neuronal damage in the brain. HA-CA ameliorates neurotoxicity and neurobehavioral deficits in 3-NP-induced HD-like symptoms in adult zebrafish.

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.

Humanistic Burden of Huntington Disease: Evidence From the Huntington Disease Burden of Illness Study

Background and Objectives

Huntington disease (HD) is a rare, inherited, and highly complex neurodegenerative disorder with no currently approved disease-modifying treatments. We investigated the effect of HD on health-related quality of life and other patient-reported outcomes in the Huntington's Disease Burden of Illness (HDBOI) study.

Methods

The HDBOI study is a retrospective, cross-sectional study conducted between September 2020 and May 2021 in France, Germany, Italy, Spain, the United Kingdom, and the United States. People with symptomatic onset HD (PwHD) were recruited by their HD-treating physicians and categorized as early (ES), mid (MS), or advanced stage (AS) HD. Physicians provided sociodemographic and clinical information from the participant's medical records in electronic case report forms (eCRF); participants or their proxies completed online Patient Public Involvement Engagement questionnaires (PPIE-P). Patient-reported outcomes included the 5-level EQ-5D version (EQ-5D-5L), Short-Form-(SF)-36 v2 (and SF-6-Dimension [SF-6D] utility), Huntington Quality of Life Instrument (H-QoL-I), and the Work Productivity and Activity Impairment Specific Health Problem. All outcomes were summarized using descriptive statistics, and differences between disease stages were assessed by Kruskal-Wallis tests.

Results

A total of 2,094 PwHD were enrolled with completed eCRFs (100%) and PPIE-P forms (n = 482, 23%). Participants' mean age was 47.3 years; they were generally evenly distributed across countries, with the majority being ES (40%) followed by MS (33%) and LS (26%). The mean EQ-5D-5L (n = 336) utility score was 0.59 (SD, 0.27), with the highest mean utility scores [SD] in ES (0.72 [0.22]) followed by MS (0.62 [0.18]) and AS (0.37 [0.30]), p < 0.001. The mean SF-6D score (n = 482) was 0.57 (SD, 0.10), with mean values decreasing with advanced disease (ES, 0.61; MS, 0.56; AS, 0.50, p < 0.001). H-QoL-I mean scores (n = 482) also worsened with more advanced disease, from 0.58 for ES to 0.49 for MS and 0.37 for AS, p < 0.001. Impairment in daily activities and in work productivity also increased with more advanced disease. Overall proxy respondents reported on average worse outcomes than PwHD (self-reported) across all outcomes and disease stages suggesting a possible unawareness of deficits by PwHD.

Discussion

The HDBOI study provides new insights into the characteristics and humanistic burden of PwHD and offers a meaningful contribution to this underserved research area.

Pathogenesis of Huntington's Disease: An Emphasis on Molecular Pathways and Prevention by Natural Remedies

BACKGROUND

Huntington's disease is an inherited autosomal dominant trait neuro-degenerative disorder caused by changes (mutations) of a gene called huntingtin (htt) that is located on the short arm (p) of chromosome 4, CAG expansion mutation. It is characterized by unusual movements, cognitive and psychiatric disorders.

OBJECTIVE

This review was undertaken to apprehend biological pathways of Huntington's disease (HD) pathogenesis and its management by nature-derived products. Natural products can be lucrative for the management of HD as it shows protection against HD in pre-clinical trials. Advanced research is still required to assess the therapeutic effectiveness of the known organic products and their isolated compounds in HD experimental models.

SUMMARY

Degeneration of neurons in Huntington's disease is distinguished by progressive loss of motor coordination and muscle function. This is due to the expansion of CAG trinucleotide in the first exon of the htt gene responsible for neuronal death and neuronal network degeneration in the brain. It is believed that the factors such as molecular genetics, oxidative stress, excitotoxicity, mitochondrial dysfunction, neuroglia dysfunction, protein aggregation, and altered UPS leads to HD. The defensive effect of the natural product provides therapeutic efficacy against HD. Recent reports on natural drugs have enlightened the protective role against HD via antioxidant, anti-inflammatory, antiapoptotic, and neurofunctional regulation.

Prevalence of neurodegenerative/demyelinating disorders in patients with achalasia

Introduction

Esophageal achalasia is a primary motility disorder. Although the exact pathogenesis is unknown, autoimmune, and neurodegenerative processes seem to be involved similarly to neurodegenerative and/or demyelinating disorders (NDDs). We hypothesized that the prevalence of NDD may be higher among patients with achalasia and vice versa as the background pathogenetic mechanisms are similar.

Methods

This was a prospective, comparative questionnaire-based study. Patients with achalasia and patients with NDD were enrolled. Selected patients with achalasia were thoroughly examined by a neurologist and selected patients with NDD were examined by a gastroenterologist to confirm or rule out NDD or achalasia. We assessed the prevalence of both achalasia and NDD and compared them with their prevalence in general population.

Results

A total of 150 patients with achalasia and 112 patients with NDD were enrolled. We observed an increased prevalence of NDD among patients with achalasia (6.0% (9/150); 95% CI (confidence interval): 3.1–11.2%) as compared to the estimated 2.0% prevalence in general population (p = 0.003). Although 32 out of 112 patients (28.6%) with NDD reported dysphagia, we did not observe significantly increased prevalence of achalasia in these patients (1.8% (2/112) vs 0.8% in general population, p = 0.226).

Conclusion

The prevalence of NDD was significantly higher among patients with achalasia (6.0%) compared to general population (2.0%), suggesting an association of these disorders. Large-volume studies are necessary to confirm this finding.

Computational insights into missense mutations in HTT gene causing Huntington's disease and its interactome networks

BACKGROUND

Huntington's disease is a rare neurodegenerative illness of the central nervous system that is inherited in an autosomal dominant pattern. Mutant huntingtin protein is produced as a result of enlargement of CAG repeat in the N-terminal of the polyglutamine tract.

AIM OF THE STUDY

Herein, we aim to investigate the mutations and their effects on the HTT gene and its genetic variants. Additionally, the protein-protein interaction of HTT with other proteins and receptor-ligand interaction with the three-dimensional structure of huntingtin protein were identified.

METHODS

A comprehensive analysis of the HTT interactome and protein-ligand interaction has been carried out to provide a global picture of structure-function analysis of huntingtin protein. Mutations were analyzed and mutation verification tools were used to check the effect of mutation on protein function.

RESULTS

The results showed, mutations in a single gene are not only responsible for causing a particular disease but may also cause other hereditary disorders as well. Moreover, the modification at the nucleotide level also cause the change in the specific amino acid which may disrupt the function of HTT and its interacting proteins contributing in disease pathogenesis. Furthermore, the interaction between MECP2 and BDNF lowers the rate of transcriptional activity. Molecular docking further confirmed the strong interaction between MECP2 and BDNF with highest affinity. Amino acid residues of the HTT protein, involved in the interaction with tetrabenazine were N912, Y890, G2385, and V2320. These findings proved, tetrabenazine as one of the potential therapeutic agent for treatment of Huntington's disease.

CONCLUSION

These results give further insights into the genetics of Huntington's disease for a better understanding of disease models which will be beneficial for the future therapeutic studies.

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.

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.

Barriers and Motivations to Provide Dental Care to Adult Patients with Movement Disorders

Patients with movement disorders, like Parkinson's and Huntington's diseases, tend to have poor oral health. Although contributing factors have been proposed, the willingness and ability of dentists to treat this patient population are still unknown. Our objective is to understand the current barriers and motivations of dentists to treat this patient population as a path to improved care and quality of life. A total of 176 dentists in Texas were surveyed through a structured questionnaire which contained both closed and open-ended questions. Nearly 30% of participants reported having no barriers to treating these patients and 26.7% reported that no such patients have visited their practice. Barriers reported included lack of education on the topic (17.6%) and longer appointments than average (14.8%). A main motivation to treat these patients was more training and education on the subject (38.6%). Poor oral health in patients with movement disorders may not be due to barriers encountered by dentists, but rather encountered by patients, such as access to and use of dental treatment. General dentists are willing to provide care for adult patients with movement disorders and continuing education for these providers is preferred over referral to a specialist.

Polyglutamine Expansion in Huntingtin and Mechanism of DNA Damage Repair Defects in Huntington’s Disease

Emerging evidence suggests that DNA repair deficiency and genome instability may be the impending signs of many neurological diseases. Genome-wide association (GWAS) studies have established a strong correlation between genes that play a role in DNA damage repair and many neurodegenerative diseases, including Huntington’s disease (HD), and several other trinucleotides repeat expansion-related hereditary ataxias. Recently, many reports have documented a significant role played by the DNA repair processes in aging and in modifying many neurodegenerative diseases, early during their progression. Studies from our lab and others have now begun to understand the mechanisms that cause defective DNA repair in HD and surprisingly, many proteins that have a strong link to known neurodegenerative diseases seem to be important players in these cellular pathways. Mutations in huntingtin (HTT) gene that lead to polyglutamine repeat expansion at the N-terminal of HTT protein has been shown to disrupt transcription-coupled DNA repair process, a specialized DNA repair process associated with transcription. Due to the recent progress made in understanding the mechanisms of DNA repair in relation to HD, in this review, we will mainly focus on the mechanisms by which the wild-type huntingtin (HTT) protein helps in DNA repair during transcription, and the how polyglutamine expansions in HTT impedes this process in HD. Further studies that identify new players in DNA repair will help in our understanding of this process in neurons. Furthermore, it should help us understand how various DNA repair mechanism(s) coordinate to maintain the normal physiology of neurons, and provide insights for the development of novel drugs at prodromal stages of these neurodegenerative diseases.

Recent developments in the management of Huntington's disease

Huntington's disease (HD) is a rare, incurable, inheritedneurodegenerative disorder manifested by chorea, hyperkinetic, and hypokinetic movements. The FDA has approved only two drugs, viz. tetrabenazine, and deutetrabenazine, to manage the chorea associated with HD. However, several other drugs are used as an off-label to manage chorea and other symptoms such as depression, anxiety, muscle tremors, and cognitive dysfunction associated with HD. So far, there is no disease-modifying treatment available. Drug repurposing has been a primary drive to search for new anti-HD drugs. Numerous molecular targets along with a wide range of small molecules and gene therapies are currently under clinical investigation. More than 200 clinical studies are underway for HD, 75% are interventional, and 25% are observational studies. The present review discusses the small molecule clinical pipeline and molecular targets for HD. Furthermore, the biomarkers, diagnostic tests, gene therapies, behavioral and observational studies for HD were also deliberated.

Understanding the Burdens Associated with Huntington’s Disease in Manifest Patients and Care Partners–Comparing to Parkinson’s Disease and the General Population

Background: The study provides real-world data on the impact of Huntington’s disease (HD) from the perspective of individuals with HD (IHD) and care partners (HD-CP) and contextualizes these results relative to Parkinson’s disease (PD) and the general population (GP). Methods: Cross-sectional survey of IHD and HD-CP in the US (July 2019–August 2019) conducted using the Rare Patient Voice panel. Data for individuals with Parkinson’s Disease (IPD), the general population (GP), and respective care partners (PD-CP; GP-CP) came from the 2018 US National Health and Wellness Survey. Outcomes included demographics, mental health, clinical characteristics, and health-related quality of life (HRQoL). Results: IHD had greater comorbid anxiety (IHD = 51.2%, IPD = 28.8%, GP = 2.0%), and HD-CP had greater comorbid anxiety (HD-CP = 52.5%, PD-CP = 28.6%, GP-CP = 19.6%) and depression (HD-CP = 65.0%, PD-CP = 29.9%, GP-CP = 19.6%), relative to other cohorts (p < 0.05). Respective of their GP cohorts, IHD exhibited lower HRQoL (EQ-5D: 0.66 ± 0.21 vs. 0.81 ± 0.17) and greater depression (PHQ-9: 11.59 ± 7.20 vs. 5.85 ± 6.71), whereas HD-CP exhibited greater depression only (PHQ-9: 6.84 ± 6.38 vs. 4.15 ± 5.58) (p < 0.001). No differences were observed between HD/HD-CP and PD/PD-CP cohorts on PHQ-9 or HRQoL. Conclusions: HD has a significant burden on patients and care partners, which is higher than GP. Notably, anxiety and depression were greater among HD vs. PD, despite similar HRQoL.

The Efficacy and Safety of Pridopidine on Treatment of Patients with Huntington's Disease: A Systematic Review and Meta-Analysis

BACKGROUND

Pridopidine is a novel drug that helps stabilize psychomotor function in patients with Huntington's disease (HD) by activating the cortical glutamate pathway. It promises to achieve the unmet needs of current therapies of HD without worsening other symptoms.

OBJECTIVE

To review the literature discussing the efficacy of pridopidine in alleviating motor symptoms and its safety in patients with HD.

METHODS

We searched Scopus, Web of Science, the Cochrane Library, Wiley, and PubMed for randomized controlled trials (RCTs) of pridopidine on HD. Data from eligible studies were extracted and pooled as mean differences for efficacy and risk ratios (RRs) for safety using RevMan software version 5.3.

RESULTS

A total of 4 relevant RCTs with 1130 patients were selected (816 in the pridopidine group and 314 in the placebo group). The pooled effect size favored pridopidine over placebo insignificantly in the Unified Huntington's Disease Rating Scale Total Motor Score (mean difference [MD], -0.93; 95% confidence interval [CI], -2.01 to 0.14; P = 0.09), whereas the effect size of 3 studies significantly favored pridopidine over placebo in the Unified Huntington's Disease Rating Scale Modified Motor Score (MD, -0.81; 95% CI, -1.48 to -0.13; P = 0.02). Pridopidine generally was well tolerated. None of the adverse effects were considerably higher in the case of pridopidine compared with placebo in overall adverse events (RR, 1.03; 95% CI, 0.94-1.13; P = 0.49) and serious adverse events (RR, 1.62; 95% CI, 0.88-2.99; P = 0.12).

CONCLUSION

The effects of pridopidine on motor functions (especially voluntary movements) in patients with HD are encouraging and provide a good safety profile that motivates further clinical trials on patients to confirm its effectiveness and safety.

Epidemiology and economic burden of Huntington's disease: a Canadian provincial public health system perspective

AIMS

To evaluate the epidemiology, healthcare resource utilization, and direct healthcare costs associated with Huntington's disease in a Canadian setting with a universal healthcare system.

MATERIALS AND METHODS

Using Albertan administrative health data, a retrospective cohort was identified applying an algorithm requiring two HD diagnostic codes within two years, using the first record as the index date (i.e. proxy for diagnosis date), from 1 April 2010 to 31 March 2019 for patients ≥21 years old. Incidence/prevalence measures were evaluated from 1 April 2010 to 31 March 2019, while healthcare resource utilization and healthcare costs per person-year (inflated to 2020 Canadian dollars) were evaluated from index to the end of follow-up (death, moved out of province, or 31 March 2020).

RESULTS

Mean [standard deviation] age at index (n = 395) was 53.9 [13.8] years and 53.7% were female. From 2010 to 2019, annual HD incidence varied between 0.47 and 1.21/100,000 person-years and HD prevalence increased from 7.25 to 9.33/100,000 persons. The mean number of visits per person-year for general and specialist practitioners was 19.2 [18.8] and 12.2 [25.5], respectively. The mean total all-cause direct healthcare costs were $23,211 [$38,599] per person-year, with hospitalizations accounting for 57.8% of all-cause costs. Costs were higher among individuals with a long-term care stay, a proxy for disease severity.

LIMITATIONS AND CONCLUSIONS

This study utilizes administrative health data to describe the epidemiology of HD and utilization of publicly funded care by individuals with HD. While administrative data presents limitations since it is not collected for research purposes, it provides a population-level examination of the burden of HD. There was a substantial economic burden associated with HD in a Canadian setting.

Sporadic Huntington's disease in the Philippines: a case report

Huntington's disease (HD) is an autosomal dominant neurodegenerative disorder with core clinical features of choreoathetosis, cognitive deficits and behavioral changes. It is a rare disorder, primarily affecting the Caucasian population, and rarely Asians. To date, there are only two reported, genetically proven familial HD cases in the Philippines. We present the case of a 39-year-old Filipino male with a 10-year history of progressive behavior and personality changes followed by cognitive decline and choreoathetotic movements. Neuroimaging showed atrophy of both caudate and putamen with putaminal rim sign. Genetic testing revealed a 47 CAG trinucleotide repeats in the Huntingtin gene; family history is negative. This is the first, genetically proven, sporadic and the third HD case in the Philippines. Despite its rarity, this report highlights the importance of including HD as a possible cause of adult-onset chorea among Filipinos.

Cognitive and social cognition deficits in Huntington's disease differ between the prodromal and the manifest stages of the condition: A scoping review of recent evidence

OBJECTIVE

Huntington's disease (HD) is a dramatic neurodegenerative disorder encompassing severe motor symptoms coupled to significant cognitive and social cognition deficits. However, it is not clear whether and how patients' neuropsychological profile changes between the prodromal and the manifest stages of the condition. The aim of the present in-depth review is to consider cognitive and social cognition impairment in HD patients by differentiating deficits arising before diagnosis from those evident from the manifest phase onwards.

METHODS

Electronic databases were searched between January 1^st , 2010 and December 31^st , 2020 by using multiple combinations of keywords related to the investigation of neuropsychological profile in HD for preliminary search, and by defining strict selection criteria for studies to be included.

RESULTS

Forty-two studies were included. Evidence suggests that the neuropsychological profile in HD reflects a complex pathological spectrum of deficits. It includes impairment in the realms of executive functions, memory, attention, information processing, and social cognition. Interestingly, patients' profiles differ significantly between the manifest and the prodromal stages of their condition, not only in quantitative terms but also from a qualitative point of view.

CONCLUSIONS

Researchers and clinicians should thus include in clinical routine timely and specific neuropsychological assessments in order to monitor patients' cognitive status as time goes by, with the ultimate goal to implement effective clinical management strategies.

PRACTITIONER POINTS

The neuropsychological profile in HD encompasses a complex pathological spectrum of deficits. Patients' profiles differ significantly between the manifest and the prodromal stages of their condition. Clinicians should include in everyday practice a timely and specific neuropsychological assessment. Detecting patients' cognitive status during the early stages of the condition already can contribute significantly to implement effective clinical management strategies.

Huntington's Disease in Israel: A Population-Based Study Using 20 Years of Routinely-Collected Healthcare Data

BACKGROUND

Huntington's disease (HD) is a rare, genetic, neurodegenerative disease. Obtaining population-level data on epidemiology and disease management is challenging.

OBJECTIVE

To investigate the epidemiology, clinical manifestations, treatment, and healthcare utilization of patients with HD in Israel.

METHODS

Retrospective population-based cohort study, including 20 years of routinely collected data from Maccabi Healthcare Services, an insurer and healthcare provider for one-quarter of the Israeli population.

RESULTS

The study cohort included 109 adult patients (aged ≥18 years) diagnosed with HD, with mean age of 49.9 years and 56%females. The most common HD-related conditions were anxiety (40%), behavioral problems (34%), sleep disorders (21%), and falls (13%). Annual incidence rates for HD ranged from 0.17 to 1.34 per 100,000 from 2000 to 2018; the 2018 crude prevalence in adults was 4.36 per 100,000. Median survival from diagnosis was approximately 12 years (95%CI: 10.4-15.3). The most frequent symptomatic treatments were antidepressants (69%), antipsychotics (63%), and tetrabenazine (63%), the only drug approved for the treatment of HD chorea in Israel during the examined period. Patterns of healthcare utilization changed as disease duration increased, reflected by increased frequency of emergency department visits and home visits.

CONCLUSION

This retrospective population-based study provides insights into the prevalence, incidence, clinical profile, survival, and resource utilization of patients with HD in ethnically diverse Israel. The findings in this study are generally consistent with the international literature and demonstrate the value of routinely collected healthcare data as a complementary resource in HD research.

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.

PLGA-Based Nanoparticles for Neuroprotective Drug Delivery in Neurodegenerative Diseases

Treatment of neurodegenerative diseases has become one of the most challenging topics of the last decades due to their prevalence and increasing societal cost. The crucial point of the non-invasive therapeutic strategy for neurological disorder treatment relies on the drugs' passage through the blood-brain barrier (BBB). Indeed, this biological barrier is involved in cerebral vascular homeostasis by its tight junctions, for example. One way to overcome this limit and deliver neuroprotective substances in the brain relies on nanotechnology-based approaches. Poly(lactic-co-glycolic acid) nanoparticles (PLGA NPs) are biocompatible, non-toxic, and provide many benefits, including improved drug solubility, protection against enzymatic digestion, increased targeting efficiency, and enhanced cellular internalization. This review will present an overview of the latest findings and advances in the PLGA NP-based approach for neuroprotective drug delivery in the case of neurodegenerative disease treatment (i.e., Alzheimer's, Parkinson's, Huntington's diseases, Amyotrophic Lateral, and Multiple Sclerosis).

Purinergic Signaling in the Pathophysiology and Treatment of Huntington's Disease

Huntington’s disease (HD) is a devastating, progressive, and fatal neurodegenerative disorder inherited in an autosomal dominant manner. This condition is characterized by motor dysfunction (chorea in the early stage, followed by bradykinesia, dystonia, and motor incoordination in the late stage), psychiatric disturbance, and cognitive decline. The neuropathological hallmark of HD is the pronounced neuronal loss in the striatum (caudate nucleus and putamen). The striatum is related to the movement control, flexibility, motivation, and learning and the purinergic signaling has an important role in the control of these events. Purinergic signaling involves the actions of purine nucleotides and nucleosides through the activation of P2 and P1 receptors, respectively. Extracellular nucleotide and nucleoside-metabolizing enzymes control the levels of these messengers, modulating the purinergic signaling. The striatum has a high expression of adenosine A_2A receptors, which are involved in the neurodegeneration observed in HD. The P2X7 and P2Y2 receptors may also play a role in the pathophysiology of HD. Interestingly, nucleotide and nucleoside levels may be altered in HD animal models and humans with HD. This review presents several studies describing the relationship between purinergic signaling and HD, as well as the use of purinoceptors as pharmacological targets and biomarkers for this neurodegenerative disorder.

The known burden of Huntington disease in the North of Scotland: prevalence of manifest and identified pre-symptomatic gene expansion carriers in the molecular era

BACKGROUND

Huntington disease prevalence was first estimated in Grampian, northern Scotland in 1984. Molecular testing has since increased ascertainment.

OBJECTIVE

To estimate the prevalence of manifest Huntington disease and identified pre-symptomatic gene expansion carriers (IPGEC) in northern Scotland, and estimate the magnitude of biases in prevalence studies that rely upon routine coding in primary care records.

METHODS

Cases were ascertained using North of Scotland genetic laboratory, clinic, and hospital records. Prevalence was calculated for manifest and IPGEC on 01/07/2016 and 01/01/2020 and compared with local published data.

RESULTS

The prevalence of manifest Huntington disease in northern Scotland in 2020 was 14.6 (95% CI 14.3-15.3) per 100,000, and of IPGEC was 8.3 (95% CI 7.8-9.2) per 100,000. Whilst the population of northern Scotland decreased by 0.05% between 2016 and 2020, the number of manifest and identified pre-symptomatic gene expansion carriers increased by 7.4% and 23.3%, respectively. Manifest disease in Grampian increased by 45.9% between 1984 and 2020. More women than men had a diagnosis. General Practice coding underestimated symptomatic molecularly confirmed prevalence by 2.2 per 100,000 people.

CONCLUSION

Even in an area with previously high ascertainment, there has been a 45.9% increase in manifest Huntington disease over the last 30 years. Within our catchment area, prevalence varies between health board regions with similar community-based services. Such variation in prevalence could have major drug cost and service delivery implications, especially if expensive, complexly administered therapies prove successful. Health services should gather accurate population-based data on a regional basis to inform service planning.

Neuroprotective effects of roflumilast against quinolinic acid-induced rat model of Huntington's disease through inhibition of NF-κB mediated neuroinflammatory markers and activation of cAMP/CREB/BDNF signaling pathway

Huntington's disease (HD) is a progressive neurodegenerative and hyperkinetic movement disorder. Decreased activity of cAMP-responsive element-binding protein (CREB) is thought to contribute to the death of striatal medium spiny neurons in HD. The present study has been designed to explore the possible role of roflumilast against qunilonic acid (QA) induced neurotoxicity in rats intending to investigate whether it inhibits the neuroinflammatory response through activation of the cAMP/CREB/BDNF signaling pathway. QA was microinjected (200 nmol/2 µl, bilaterally) through the intrastriatal route in the stereotaxic apparatus. Roflumilast (0.5, 1, and 2 mg/kg, orally) once-daily treatment for 21 days significantly improved locomotor activity in actophotometer, motor coordination in rotarod, and impaired gait performance in narrow beam walk test. Moreover, roflumilast treatment significantly attenuated oxidative and nitrosative stress (p < 0.05) through attenuating lipid peroxidation nitrite concentration and enhancing reduced glutathione, superoxide dismutase, and catalase levels. Furthermore, roflumilast also significantly decreased elevated pro-inflammatory cytokines like TNF-α (p < 0.01), IL-6 (p < 0.01), IFN-γ (p < 0.05), NF-κB (p < 0.05) and significantly increased BDNF(p < 0.05) in the striatum and cortex of rat brain. The results further demonstrated that roflumilast effectively increased the gene expression of cAMP(p < 0.05), CREB(p < 0.05) and decreased the gene expression of PDE4 (p < 0.05) in qRT-PCR. These results conclusively depicted that roflumilast could be a potential candidate as an effective therapeutic agent in the management of HD through the cAMP/CREB/BDNF signaling pathway.

Mutant Huntingtin stalls ribosomes and represses protein synthesis in a cellular model of Huntington disease

The polyglutamine expansion of huntingtin (mHTT) causes Huntington disease (HD) and neurodegeneration, but the mechanisms remain unclear. Here, we found that mHtt promotes ribosome stalling and suppresses protein synthesis in mouse HD striatal neuronal cells. Depletion of mHtt enhances protein synthesis and increases the speed of ribosomal translocation, while mHtt directly inhibits protein synthesis in vitro. Fmrp, a known regulator of ribosome stalling, is upregulated in HD, but its depletion has no discernible effect on protein synthesis or ribosome stalling in HD cells. We found interactions of ribosomal proteins and translating ribosomes with mHtt. High-resolution global ribosome footprint profiling (Ribo-Seq) and mRNA-Seq indicates a widespread shift in ribosome occupancy toward the 5' and 3' end and unique single-codon pauses on selected mRNA targets in HD cells, compared to controls. Thus, mHtt impedes ribosomal translocation during translation elongation, a mechanistic defect that can be exploited for HD therapeutics.

Speech and language difficulties in Huntington's disease: A qualitative study of patients' and professional caregivers' experiences

BACKGROUND

Huntington's disease (HD) is a neurodegenerative disease characterized by a triad of motor, cognitive and psychological symptoms, leading to a gradual breakdown of communication skills. Few studies have investigated how people affected by HD and their professional caregivers, for example, medical doctors, physiotherapists and nurses, experience the patients' gradual loss of speech and language.

AIMS

To examine communication-related experiences of patients and professional caregivers. Experiences with speech therapy and the use of augmentative and alternative communication aids (AAC) were also investigated.

METHODS & PROCEDURES

Seven individuals with HD and seven professional caregivers were interviewed individually, using a semi-structured interview guide. Transcripts were analysed using a conventional content analysis, and the results presented in three main categories.

OUTCOMES & RESULTS

Most individuals with HD were aware of having communication difficulties, struggling with understanding others as well as being understood. This was confirmed by professional caregivers, who also raised ethical issues encountered when patients struggled with communication. Both groups talked about external factors (such as noise or crowded social settings) as disrupting communication, and shared recommendations on how people in general, and speech and language therapists (SLTs) in particular, could optimize communication. Very few patients had received information about communication aids, and none was using AACs. Professional caregivers underlined the importance of interdisciplinary collaborations, including SLTs, in order to optimize care.

CONCLUSIONS & IMPLICATIONS

Findings shed a light on everyday communication challenges faced by people with HD and their professional caregivers, and the lack of implementation of communication aids in this group. The dramatic impact of HD on patients' communication skills underscores the need to include SLTs in the follow-up of this patient group, ideally from the early stages of the disease, while the patient is still capable of voicing his/her own wishes and thoughts. Future research that explores how to optimize communication and implement the use of AACs for individuals with HD is needed. What this paper adds What is already known on this subject Although the ability to communicate gradually deteriorates in individuals affected by Huntington's disease (HD), there is little knowledge about how affected individuals experience the loss of speech and language skills. Interdisciplinary care is recognised as essential for this patient group. However, professional caregivers' thoughts and experiences of communicating with their patients have not been fully explored. Recent years have seen a rapid growth of available communication supporting technologies that could potentially be helpful for individuals with HD, but limited attention has been given to this subject. What this paper adds to existing knowledge What do we now know as a result of this study that we did not know before the results highlight that patients are aware of problems with speech and language even in early phases of the disease, and include patients' personal outlook on problems with communication. Professional caregivers raised ethical issues encountered when patients struggled with communication. Both groups described specific strategies that could facilitate communication. There was a significant lack of experience and knowledge about augmentative and alternative communication aids (AACs). What are the potential or actual clinical implications of this work? Clinical implications of this study. The introduction of communication aids in the follow-up of patients with HD needs to be discussed with the patients in the early phases of the disease, and implemented while the individual still has the capacity to learn and take advantage of alternative communication support. Results underline the importance of including speech and language therapists (SLTs) into multidisciplinary care of patients with HD. SLTs should be available also for professional caregivers who need advice on how to facilitate conversations and social interactions, in order to optimise care of patients with HD.

Understanding stem cells and its pivotal role in regenerative medicine

Stem cells (SCs) are clonogenic cells that develop into the specialized cells which later responsible for making up various types of tissue in the human body. SCs are not only the appropriate source of information for cell division, molecular and cellular processes, and tissue homeostasis but also one of the major putative biological aids to diagnose and cure various degenerative diseases. This study emphasises on various research outputs that occurred in the past two decades. This will give brief information on classification, differentiation, detection, and various isolation techniques of SCs. Here, the various signalling pathways which includes WNT, Sonic hedgehog, Notch, BMI1 and C-met pathways and how does it effect on the regeneration of various classes of SCs and factors that regulates the potency of the SCs are also been discussed. We also focused on the application of SCs in the area of regenerative medicine along with the cellular markers that are useful as salient diagnostic or curative tools or in both, by the process of reprogramming, which includes diabetes, cancer, cardiovascular disorders and neurological disorders. The biomarkers that are mentioned in various literatures and experiments include PDX1, FOXA2, HNF6, and NKX6-1 (for diabetes); CD33, CD24, CD133 (for cancer); c-Kit, SCA-1, Wilm's tumor 1 (for cardiovascular disorders); and OCT4, SOX2, c-MYC, EN1, DAT and VMAT2 (for neurological disorders). In this review, we come to know the advancements and scopes of potential SC-based therapies, its diverse applications in clinical fields that can be helpful in the near future.

Alleviation of Huntington pathology in mice by oral administration of food additive glyceryl tribenzoate

Huntington's disease (HD) is a neurodegenerative disorder characterized by accumulation of mutant huntingtin protein and significant loss of neurons in striatum and cortex. Along with motor difficulties, the HD patients also manifest anxiety and loss of cognition. Unfortunately, the clinically approved drugs only offer symptomatic relief and are not free from side effects. This study underlines the importance of glyceryl tribenzoate (GTB), an FDA-approved food flavoring ingredient, in alleviating HD pathology in transgenic N171-82Q mouse model. Oral administration of GTB significantly reduced mutant huntingtin level in striatum, motor cortex as well as hippocampus and increased the integrity of viable neurons. Furthermore, we found the presence of sodium benzoate (NaB), a FDA-approved drug for urea cycle disorders and glycine encephalopathy, in the brain of GTB-fed HD mice. Accordingly, NaB administration also markedly decreased huntingtin level in striatum and cortex. Glial activation is found to coincide with neuronal death in affected regions of HD brains. Interestingly, both GTB and NaB treatment suppressed activation of glial cells and inflammation in the brain. Finally, neuroprotective effect of GTB and NaB resulted in improved motor performance of HD mice. Collectively, these results suggest that GTB and NaB may be repurposed for HD.

Validation of diagnostic codes and epidemiologic trends of Huntington disease: a population-based study in Navarre, Spain

BACKGROUND

There is great heterogeneity on geographic and temporary Huntington disease (HD) epidemiological estimates. Most research studies of rare diseases, including HD, use health information systems (HIS) as data sources. This study investigates the validity and accuracy of national and international diagnostic codes for HD in multiple HIS and analyses the epidemiologic trends of HD in the Autonomous Community of Navarre (Spain).

METHODS

HD cases were ascertained by the Rare Diseases Registry and the reference Medical Genetics Centre of Navarre. Positive predictive values (PPV) and sensitivity with 95% confidence intervals (95% CI) were estimated. Overall and 9-year periods (1991-2017) HD prevalence, incidence and mortality rates were calculated, and trends were assessed by Joinpoint regression.

RESULTS

Overall PPV and sensitivity of combined HIS were 71.8% (95% CI: 59.7, 81.6) and 82.2% (95% CI: 70.1, 90.4), respectively. Primary care data was a more valuable resource for HD ascertainment than hospital discharge records, with 66% versus 50% sensitivity, respectively. It also had the highest number of "unique to source" cases. Thirty-five per cent of HD patients were identified by a single database and only 4% by all explored sources. Point prevalence was 4.94 (95% CI: 3.23, 6.65) per 100,000 in December 2017, and showed an annual 6.1% increase from 1991 to 1999. Incidence and mortality trends remained stable since 1995-96, with mean annual rates per 100,000 of 0.36 (95% CI: 0.27, 0.47) and 0.23 (95% CI: 0.16, 0.32), respectively. Late-onset HD patients (23.1%), mean age at onset (49.6 years), age at death (66.6 years) and duration of disease (16.7 years) were slightly higher than previously reported.

CONCLUSION

HD did not experience true temporary variations in prevalence, incidence or mortality over 23 years of post-molecular testing in our population. Ascertainment bias may largely explain the worldwide heterogeneity in results of HD epidemiological estimates. Population-based rare diseases registries are valuable instruments for epidemiological studies on low prevalence genetic diseases, like HD, as long as they include validated data from multiple HIS and genetic/family information.

Therapeutic and Mechanistic Effects of Curcumin in Huntington's Disease

Curcumin is a spice derived nutraceutical which gained tremendous attention because of its profound medicinal values. It alters a number of molecular pathways such as nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), signal transducer and activator of transcription 3 (STAT3), nuclear factor erythroid 2-related factor 2 (Nrf2) and cyclooxygenases-2 (COX-2), which make it potential therapeutic choice in treating multiple disorders. It also possesses the potential to prevent protein aggregation and thus protect against degeneration of neurons in neurodegenerative disorders including Huntington's disease (HD). HD is an autosomal dominant disorder linked with altered gene expression which leads to an increase in the size of cytosine, adenine and guanine (CAG) trinucleotide repeats, aids in protein aggregation throughout the brain and thus damages neurons. Upstream regulation of oxidative stress and inflammatory cascade are two important factors that drive HD progression. Available therapies just suppress the severity of symptoms with a number of side effects. Curcumin targets multiple mechanisms in treating or preventing HD including antioxidant and anti-inflammatory potential, metal ion chelation, transcriptional alterations and upregulating activity of molecular chaperons, heat shock proteins (HSPs). Having a favorable safety profile, curcumin can be an alternative therapeutic choice in treating neurodegenerative disorders like HD. This review will focus on mechanistic aspects of curcumin in treating or preventing HD and its potential to arrest disease progression and will open new dimensions for safe and effective therapeutic agents in diminishing HD.

The Renin-Angiotensin System in Huntington's Disease: Villain or Hero?

Huntington’s Disease (HD) is an autosomal dominant, progressive neurodegenerative disorder characterized by severe symptoms, including motor impairment, cognitive decline, and psychiatric alterations. Several systems, molecules, and mediators have been associated with the pathophysiology of HD. Among these, there is the Renin-Angiotensin System (RAS), a peptide hormone system that has been associated with the pathology of neuropsychiatric and neurodegenerative disorders. Important alterations in this system have been demonstrated in HD. However, the role of RAS components in HD is still unclear and needs further investigation. Nonetheless, modulation of the RAS components may represent a potential therapeutic strategy for the treatment of HD.

C9orf72 Hexanucleotide Repeat in Huntington-Like Patients: Systematic Review and Meta-Analysis

Introduction: Patients with Huntington-Like disorders (HLD) comprise a variety of allelic disorders sharing a Huntington phenotype. The hexanucleotide repeat expansion of the C9orf72 gene could explain part of the HLD etiology. We aimed to conduct a systematic review and meta-analysis looking for the frequency of the hexanucleotide repeat expansion of the C9orf72 gene in HLD patients. Methods: The protocol was registered on the International Prospective Register of Systematic Reviews database (PROSPERO) (registration number: CRD42018105465). The search was carried out in Medline, Scopus, Web of Science, and Embase in April 2018, and updated in July 2020. Observational studies reporting patients with HLD carrying the hexanucleotide repeat expansion in the C9orf72 gene were selected and reviewed; this process was duplicated. The cutoff threshold for considering the hexanucleotide expansion as a pathogenic variant was equal to or >30 G4C2 repeats. Cases with intermediate alleles with 20-29 repeat are also analyzed. Pooled frequency and 95% CI were calculated using random-effects models. Results: Nine out of 219 studies were selected, reporting 1,123 affected individuals with HLD. Among them, 18 individuals carried C9orf72 expansion, representing 1% (95% CI: 0-2%, I 2 = 0%) of the pooled frequency. Seven selected studies came from European centers, one was reported at a US center, and one came from a South-African center. We identified five individuals carrying intermediate alleles representing 3% (95% CI: 0-14%, I 2 = 78.5%). Conclusions: The frequency of C9orf72 unstable hexanucleotide repeat expansion in HLD patients is very low. Further studies with more accurate clinical data and from different ethnic backgrounds are needed to confirm this observation.

Prevalence of Huntington's disease in Southern Sardinia, Italy

BACKGROUND

The frequency of Huntington's disease (HD) may vary considerably, with higher estimates in non Asian populations. In Italy, two recent studies performed in Ferrara county and Molise provided different prevalence estimates, varying from 4.2 × 10⁵ to 10.8 × 10⁵. Here we present a study performed in the Southern part of Sardinia, a large Italian mediterranean island that is considered a genetic isolate.

METHODS

The study area included the two neighbouring counties of South Sardinia and Cagliari with 353,830 and 431,955 inhabitants respectively on December 31st, 2017 (prevalence date). Case-patients were ascertained through multiple sources in Sardinia and Italy.

RESULTS

We identified 54 individuals with HD, of whom 47 were alive on prevalence date. The resulting prevalence rate was 5.98 × 10⁵ in the overall study area, however with marked variations between South Sardinia and Cagliari (9.6 × 10⁵ vs. 3.0 × 10⁵, p = 0.02). In the two study areas, we found similar CAG repeat length in normal alleles (17.5 ± 2.1 vs. 17.7 ± 2.2, p = 0.5).

CONCLUSIONS

The overall prevalence of HD in Sardinia is close to the correspondent estimates in Europeans. Our findings also highlighted the possibility of local microgeographic variations in the epidemiology of HD.

Influence of 3-nitropropionic acid on physiological and behavioral responses in zebrafish larvae and adults

Long-term treatment with 3-nitropropionic acid (3-NPA), a toxin derived from plants and fungi, may reproduce symptoms and biochemical characteristics of Huntington's disease (HD). Our study evaluated the effects of 3-NPA on the physiological and behavioral responses in zebrafish larvae and adults. Larvae exposed to 0.1, 0.2, or 0.5 mM 3-NPA exhibited an increase in heart rate at 2- and 5-days post-fertilization (dpf). There was a decrease in the ocular distance at 5 dpf with 0.05 mM 3-NPA treatment. However, 3-NPA did not alter larval locomotor parameters. Adult zebrafish received 3-NPA intraperitoneal injections (a total of seven injections at doses 10, 20, or 60 mg/kg every 96 h) and showed a decrease in body weight , locomotion and aggressive behavior. No changes were observed in anxiety-like behavior and social interaction between 3-NPA-exposed animals and control groups. However, 3-NPA-treated animals (at 60 mg/kg) demonstrated impaired long-term aversive memory. Overall, 3-NPA exposure induced morphological and heart rate alterations in zebrafish larvae. Additionally, our study showed behavioral changes in zebrafish that were submitted to long-term 3-NPA treatment, which could be related to HD symptoms.