Rate of functional decline in Huntington's disease. Huntington Study Group

Real-world experience with Deutetrabenazine management in patients with Huntington's disease using video-based telemedicine

BACKGROUND

Huntington's disease (HD) is a rare progressive neurological disorder, and telemedicine has the potential to improve the quality of care for patients with HD. Deutetrabenazine (DTBZ) can reduce chorea symptoms in HD; however, there is limited experience with this medication in Asian countries.

METHODS

Retrospective and prospective studies were employed to explore the feasibility and reliability of a video-based telemedicine system for HD patient care. Reliability was demonstrated through consistency between selected-item scores (SIS) and total motor scores (TMS) and the agreement of scores obtained from hospital and home videos. Finally, a single-centre real-world DTBZ management study was conducted based on the telemedicine system to explore the efficacy of DTBZ in patients with HD.

RESULTS

There were 77 patients included in the retrospective study, and a strong correlation was found between SIS and TMS (r = 0.911, P < 0.0001), indicating good representativeness. There were 32 patients enrolled in the prospective study. The reliability was further confirmed, indicated by correlations between SIS and TMS (r = 0.964, P < 0.0001) and consistency of SIS derived from the in-person and virtual visits (r = 0.969, P < 0.0001). There were 17 patients included in the DTBZ study with a mean 1.41 (95% confidence interval, 0.37-2.46) improvement in chorea score and reported treatment success.

CONCLUSIONS

A video-based telemedicine system is a feasible and reliable option for HD patient care. It may also be used for drug management as a supplementary tool for clinical visits.

Influence of anosognosia on patient-reported outcomes for psychiatric symptoms and quality of life in Huntington's disease

INTRODUCTION

Anosognosia, defined as reduced awareness of one's deficit or symptom, is common in Huntington's disease (HD) and detectable at each disease stage. The impact of anosognosia on self-reporting in HD populations is critical to understand given growing use of patient-reported outcomes in HD clinical care and research. We aimed to determine the influence of anosognosia on patient-reported outcome measures assessing psychiatric symptoms and quality of life in HD.

METHODS

We enrolled HD patients to complete a battery of patient-reported and rater-administered measures, including the Anosognosia Scale, at baseline and 6 months later. Patient-reported outcome measures included NeuroQoL short forms for depression, anxiety, satisfaction with social roles and activities, and positive affect and well-being and Patient-Reported Outcomes Measurement Information System short forms for emotional distress-anger and sleep-related impairment. Anosognosia Scale-Difference Score indexed patient-clinician agreement on patient motor, cognitive, and behavioral abilities. We conducted multivariable linear regression analyses to quantify the association of baseline anosognosia with 6-month patient-reported outcomes.

RESULTS

Of 79 patients with complete Anosognosia Scale data at baseline, 25 (31.6 %) met the scale's criterion for anosognosia. In the regression analyses, baseline Difference Score improved prediction of 6-month patient-reported outcomes for depression, anxiety, anger, and positive affect and well-being (χ2(1) value range for likelihood ratio tests contrasting models with and without Difference Score: 13.1-20.9, p-values <0.001). Patients with more anosognosia self-reported less severe psychiatric symptoms and more positive affect and well-being.

CONCLUSION

Study results suggest that anosognosia influences patient-reported outcomes for psychiatric symptoms and quality of life in HD populations.

Viral-based animal models in polyglutamine disorders

Polyglutamine disorders are a complex group of incurable neurodegenerative disorders caused by an abnormal expansion in the trinucleotide cytosine-adenine-guanine tract of the affected gene. To better understand these disorders, our dependence on animal models persists, primarily relying on transgenic models. In an effort to complement and deepen our knowledge, researchers have also developed animal models of polyglutamine disorders employing viral vectors. Viral vectors have been extensively used to deliver genes to the brain, not only for therapeutic purposes but also for the development of animal models, given their remarkable flexibility. In a time- and cost-effective manner, it is possible to use different transgenes, at varying doses, in diverse targeted tissues, at different ages, and in different species, to recreate polyglutamine pathology. This paper aims to showcase the utility of viral vectors in disease modelling, share essential considerations for developing animal models with viral vectors, and provide a comprehensive review of existing viral-based animal models for polyglutamine disorders.

Pharmacological characterization of SAGE-718, a novel positive allosteric modulator of N-methyl-d-aspartate receptors

BACKGROUND AND PURPOSE

Select neuroactive steroids tune neural activity by modulating excitatory and inhibitory neurotransmission, including the endogenous cholesterol metabolite 24(S)-hydroxycholesterol (24(S)-HC), which is an N-methyl-d-aspartate (NMDA) receptor positive allosteric modulator (PAM). NMDA receptor PAMs are potentially an effective pharmacotherapeutic strategy to treat conditions associated with NMDA receptor hypofunction.

EXPERIMENTAL APPROACH

Using in vitro and in vivo electrophysiological recording experiments and behavioural approaches, we evaluated the effect of SAGE-718, a novel neuroactive steroid NMDA receptor PAM currently in clinical development for the treatment of cognitive impairment, on NMDA receptor function and endpoints that are altered by NMDA receptor hypoactivity and assessed its safety profile.

KEY RESULTS

SAGE-718 potentiated GluN1/GluN2A-D NMDA receptors with equipotency and increased NMDA receptor excitatory postsynaptic potential (EPSP) amplitude without affecting decay kinetics in striatal medium spiny neurons. SAGE-718 increased the rate of unblock of the NMDA receptor open channel blocker ketamine on GluN1/GluN2A in vitro and accelerated the rate of return on the ketamine-evoked increase in gamma frequency band power, as measured with electroencephalogram (EEG), suggesting that PAM activity is driven by increased channel open probability. SAGE-718 ameliorated deficits due to NMDA receptor hypofunction, including social deficits induced by subchronic administration of phencyclidine, and behavioural and electrophysiological deficits from cholesterol and 24(S)-HC depletion caused by 7-dehydrocholesterol reductase inhibition. Finally, SAGE-718 did not produce epileptiform activity in a seizure model or neurodegeneration following chronic dosing.

CONCLUSIONS AND IMPLICATIONS

These findings provide strong evidence that SAGE-718 is a neuroactive steroid NMDA receptor PAM with a mechanism that is well suited as a treatment for conditions associated with NMDA receptor hypofunction.

Association between sex and Huntington's disease: an updated review on symptomatology and prognosis of neurodegenerative disorders

Huntington's disease is a rare autosomal dominant disorder presenting with chorea, rigidity, hypo-/akinesia, cognitive decline, and psychiatric disturbances. Numerous risk factors have been defined in the onset of this disease. However, the number of CAG repeats in the genes are the most crucial factor rendering patients susceptible to the disease. Studies have shown significant differences in onset and disease presentation among the sexes, which prompts analysis of the impact of different sexes on disease etiology and progression. This article therefore discusses the evidence-based role of sex in aspects of symptomatology, pathogenesis, biomarkers, progression, and prognosis of Huntington's disease, with a secondary review of sex-linked differences in Alzheimer's and Parkinson's disease.

Large-scale screening of clinical assessments to distinguish between states in the Integrated HD Progression Model (IHDPM)

Background

Understanding the sensitivity and utility of clinical assessments across different HD stages is important for study/trial endpoint selection and clinical assessment development. The Integrated HD Progression Model (IHDPM) characterizes the complex symptom progression of HD and separates the disease into nine ordered disease states.

Objective

To generate a temporal map of discriminatory clinical measures across the IHDPM states.

Methods

We applied the IHDPM to all HD individuals in an integrated longitudinal HD dataset derived from four observational studies, obtaining disease state assignment for each study visit. Using large-scale screening, we estimated Cohen's effect sizes to rank the discriminative power of 2,472 clinical measures for separating observations in disease state pairs. Individual trajectories through IHDPM states were examined. Discriminative analyses were limited to individuals with observations in both states of the pairs compared (N = 3,790).

Results

Discriminative clinical measures were heterogeneous across the HD life course. UHDRS items were frequently identified as the best state pair discriminators, with UHDRS Motor items - most notably TMS - showing the highest discriminatory power between the early-disease states and early post-transition period states. UHDRS functional items emerged as strong discriminators from the transition period and on. Cognitive assessments showed good discriminative power between all state pairs examined, excepting state 1 vs. 2. Several non-UHDRS assessments were also flagged as excellent state discriminators for specific disease phases (e.g., SF-12). For certain state pairs, single assessment items other than total/summary scores were highlighted as having excellent discriminative power.

Conclusion

By providing ranked quantitative scores indicating discriminatory ability of thousands of clinical measures between specific pairs of IHDPM states, our results will aid clinical trial designers select the most effective outcome measures tailored to their study cohort. Our observations may also assist in the development of end points targeting specific phases in the disease life course, through providing specific conceptual foci.

An exploratory metabolomic comparison of participants with fast or absent functional progression from 2CARE, a randomized, double-blind clinical trial in Huntington's disease

Huntington's disease (HD) is increasingly recognized for diverse pathology outside of the nervous system. To describe the biology of HD in relation to functional progression, we previously analyzed the plasma and CSF metabolome in a cross-sectional study of participants who had various degrees of functional impairment. Here, we carried out an exploratory study in plasma from HD individuals over a 3-year time frame to assess whether differences exist between those with fast or absent clinical progression. There were more differences in circulating metabolite levels for fast progressors compared to absent progressors (111 vs 20, nominal p < 0.05). All metabolite changes in faster progressors were decreases, whereas some metabolite concentrations increased in absent progressors. Many of the metabolite levels that decreased in the fast progressors were higher at Screening compared to absent progressors but ended up lower by Year 3. Changes in faster progression suggest greater oxidative stress and inflammation (kynurenine, diacylglycerides, cysteine), disturbances in nitric oxide and urea metabolism (arginine, citrulline, ornithine, GABR), lower polyamines (putrescine and spermine), elevated glucose, and deficient AMPK signaling. Metabolomic differences between fast and absent progressors suggest the possibility of predicting functional decline in HD, and possibly delaying it with interventions to augment arginine, polyamines, and glucose regulation.

Factors Influencing the Total Functional Capacity Score as a Critical Endpoint in Huntington's Disease Research

Background: The Total Functional Capacity (TFC) score is commonly used in Huntington's disease (HD) research. The classification separates each disease stage (1-5), e.g., as an inclusion criterion or endpoint in clinical trials accepted by the Food and Drug Administration (FDA). In addition to the quantification of age- and CAG-repeat-dependent effects as well as interacting effects of both on the TFC, we aimed to investigate factors influencing the TFC, such as neuropsychiatric, educational, and cognitive disease burden using data from the largest HD observational study to date. In addition, we analyzed data from pre-manifest stages to investigate the influence of the above-mentioned factors on the TFC in that stage. Methods: A moderated regression analysis was conducted to analyze the interaction effects of age and CAG-repeat length on the TFC in HD patients. A simple slope analysis was calculated to illustrate the effects. Depending on TFC results, motor-manifest patients were grouped into five stages. Data from pre-manifest participants were analyzed with regard to years to onset and CAP scores. Results: We identified N = 10,314 participants as manifest HD. A significant part of variance on the TFC was explained by age (R2 = 0.029, F (1;10,281) = 308.02, p < 0.001), CAG-repeat length (∆R2 = 0.132, ∆F (1;10,280) = 1611.22, p < 0.001), and their interaction (∆R2 = 0.049, ∆F (1;10,279) = 634.12, p < 0.001). The model explained altogether 20.9% of the TFC score's variance (F = 907.60, p < 0.001). Variance of psychiatric and cognitive symptoms significantly differed between stages. Exploratory analysis of median data in pre-manifest participants revealed the highest scores for neuropsychiatric changes between 5 to <20 years from the disease onset. Conclusions: TFC is mainly explained by the neurobiological factors, CAG-repeat length, and age, with subjects having more CAG-repeats showing a faster decline in function. Our study confirms TFC as a robust measure of progression in manifest HD.

Sex Differences in Sleep Phenotypes in the BACHD Mouse Model of Huntington's Disease

Sleep and circadian rhythm disturbances are common features of Huntington's disease (HD). HD is an autosomal dominant neurodegenerative disorder that affects men and women in equal numbers, but some epidemiological studies as well as preclinical work indicate there may be sex differences in disease progression. Since sex differences in HD could provide important insights to understand cellular and molecular mechanism(s), we used the bacterial artificial chromosome transgenic mouse model of HD (BACHD) to examine whether sex differences in sleep/wake cycles are detectable in an animal model of the disease. Electroencephalography/electromyography (EEG/EMG) was used to measure sleep/wake states and polysomnographic patterns in young adult (12 week-old) male and female wild-type and BACHD mice. Our findings show that male, but not female, BACHD mice exhibited increased variation in phases of the rhythms as compared to age and sex matched wild-types. For both Rapid-eye movement (REM) and Non-rapid eye movement (NREM) sleep, genotypic and sex differences were detected. In particular, the BACHD males spent less time in NREM and exhibited a more fragmented sleep than the other groups. Both male and female BACHD mice exhibited significant changes in delta but not in gamma power compared to wild-type mice. Finally, in response to a 6-hrs sleep deprivation, both genotypes and sexes displayed predicted homeostatic responses to sleep loss. These findings suggest that females are relatively protected early in disease progression in this HD model.

"Ten euros now" temporal discounting in Huntington disease

BACKGROUND

When making decisions, one often faces a trade-off between immediate and long-term rewards. In these situations, people may prefer immediate over later rewards, even if immediate rewards are smaller than later ones; a phenomenon known as temporal discounting. In this study, we, for the first time, assessed temporal discounting in three populations: participants with manifest Huntington disease (HD), participants with premanifest HD, and control participants.

METHODS

Using the temporal discounting task, we invited participants to choose between small immediate amount of money vs. delayed, but larger amount of money (e.g., "Which do you prefer: you get 10 euros right now or 50 euros in a month?"). We also measured inhibition in order to test if it impacts discounting performance.

RESULTS

Analysis demonstrated higher temporal discounting (i.e., a preference for the immediate rewards) in participants with manifest HD compared to those with premanifest HD or control participants, but no significant differences were observed in participants with premanifest HD and control participants. Analysis also demonstrated significant correlations between temporal discounting and scores on an inhibition test in participants with manifest HD, but not in those with premanifest HD or in control participants.

DISCUSSION

We suggest that, when making decisions, patients with manifest HD may have difficulties with suppressing the temptation of smaller, but immediate, rewards.

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.

Longitudinal analysis of neuropsychiatric symptoms in a large cohort of early-moderate manifest Huntington's disease patients

BACKGROUND

The relationship between neuropsychiatric symptoms (NPS) and other clinical dimensions in Huntington's disease (HD) is controversial. This longitudinal study analyzed the association between NPS and motor, cognitive and functional aspects of the disease along with other variables related to its clinical onset and progression.

METHODS

639 early-moderate HD patients were assessed longitudinally (mean: 4.95 visits/5 years). Generalized linear mixed models were used to explore associations between NPS and the aforementioned aspects. Other variables previously reported as significant in smaller or cross-sectional studies were included in the models.

RESULTS

Significant associations found included a negative linear relationship between presence of depressed mood and illness duration (7.2% odds reduction of being depressed per year), a 7.6% increase in the odds of having irritability with increased chorea scores, a negative association (4.3% reduction in odds) between age at onset and aggression (i.e. earlier onset was related to a higher probability of having aggressive behaviors) and a negative association between irritability and the interference component of the Stroop test (3% odds change). Total functional capacity (TFC) was the most frequently associated factor with NPS, with apathy and perseverative behavior having the strongest relations with TFC (22% and 18% increases in odds per unit reduction in TFC respectively).

CONCLUSIONS

With the exception of irritability, NPS are not related to motor or cognitive variables in early-moderate HD. Total functional capacity (TFC) is the most frequently associated factor with NPS, with apathy and perseverative behavior having the strongest relations with TFC.

Sexual Dimorphism in Neurodegenerative Diseases and in Brain Ischemia

Epidemiological studies and clinical observations show evidence of sexual dimorphism in brain responses to several neurological conditions. It is suggested that sex-related differences between men and women may have profound effects on disease susceptibility, pathophysiology, and progression. Sexual differences of the brain are achieved through the complex interplay of several factors contributing to this phenomenon, such as sex hormones, as well as genetic and epigenetic differences. Despite recent advances, the precise link between these factors and brain disorders is incompletely understood. This review aims to briefly outline the most relevant aspects that differ between men and women in ischemia and neurodegenerative disorders (AD, PD, HD, ALS, and SM). Recognition of disparities between both sexes could aid the development of individual approaches to ameliorate or slow the progression of intractable disorders.

The effects of antidepressants on depressive symptoms in manifest Huntington's disease

OBJECTIVE

Currently there is little evidence to guide the treatment of depression in Huntington's disease (HD). The primary objective was to determine the effectiveness of antidepressant medications on lowering depressive symptom scores in patients with manifest HD. The secondary objective was to determine the effect of antidepressant use on measures of disease progression.

METHODS

After retrospectively identifying motor-manifest HD participants with at least borderline depressive symptoms from the Enroll-HD database, 86 new users of antidepressant medication were exact matched with non-users on depression score, and matched on propensity scores developed using age, sex, CAG repeat length, anxiety scores, and disease progression measures. Linear mixed effect models were used to assess the change in depression scores, anxiety scores, and disease progression measures based on antidepressant use between two visits approximately one-year apart.

RESULTS

There was no significant difference in the change in depression score between antidepressant users and non-users (p = 0.46). There were also no significant differences in the change in total motor score (p = 0.88), total functional capacity score (p = 0.16), number correct on the symbol digit modality test (p = 0.49), or anxiety score (p = 0.68).

CONCLUSIONS

Initiation of antidepressant medication was not associated with a greater reduction in depressive symptoms or changes in other symptoms when compared to non-use. The findings of this study support further research on the effectiveness of antidepressants in Huntington's disease patients. Clinical trials or studies with a larger sample of new antidepressant users should be used to assess the causal effects of antidepressant medications on depressive symptoms.

Decreased CSF oxytocin relates to measures of social cognitive impairment in Huntington's disease patients

OBJECTIVE

Huntington's disease (HD) is an inherited neurodegenerative disease with motor, cognitive and psychiatric symptoms. Non-motor symptoms like depression and altered social cognition are proposed to be caused by dysfunction of the hypothalamus. We measured the hypothalamic neuropeptide oxytocin in plasma and cerebrospinal fluid (CSF) in a cohort of HD gene expansion carriers (HDGECs), compared the levels to healthy HD family controls and correlated oxytocin levels to disease progression and social cognition.

METHODS

We recruited 113 HDGECs and 33 controls. Psychiatric and cognitive symptoms were evaluated, and social cognition was assessed with the Emotion Hexagon test, Reading the Mind in the Eyes and The Awareness of Social Inference Test. The levels of oxytocin in CSF and blood were analyzed by radioimmunoassay.

RESULTS

We found the level of oxytocin in CSF to be significantly lower by 33.5% in HDGECs compared to controls (p = 0.016). When dividing the HDGECs into groups with or without cognitive impairment, we found the oxytocin level to be significantly lower by 30.3% in the HDGECs with cognitive symptoms (p = 0.046). We found a statistically significant correlation between the level of oxytocin and scores on social cognition (Reading the Mind in the Eyes p = 0.0019; Emotion Hexagon test: p = 0.0062; The Awareness of Social Inference Test: p = 0.002).

CONCLUSIONS

This is the first study to measure oxytocin in the CSF of HDGECs. We find that HDGECs have a significantly lower level of oxytocin compared to controls, and that the level of oxytocin may represent an objective and comparable measure that could be used as a state biomarker for impairment of social cognition. We suggest treatment trials to evaluate a potential effect of oxytocin on social cognition in HD.

Effects of Exercise on Skeletal Muscle Pathophysiology in Huntington's Disease

Huntington's disease (HD) is a rare, hereditary, and progressive neurodegenerative disease, characterized by involuntary choreatic movements with cognitive and behavioral disturbances. In order to mitigate impairments in motor function, physical exercise was integrated in HD rehabilitative interventions, showing to be a powerful tool to ameliorate the quality of life of HD-affected patients. This review aims to describe the effects of physical exercise on HD-related skeletal muscle disorders in both murine and human models. We performed a literature search using PubMed, Scopus, and Web of Science databases on the role of physical activity in mouse models of HD and human patients. Fifteen publications fulfilled the criteria and were included in the review. Studies performed on mouse models showed a controversial role played by exercise, whereas in HD-affected patients, physical activity appeared to have positive effects on gait, motor function, UHDMRS scale, cognitive function, quality of life, postural stability, total body mass, fatty acid oxidative capacity, and VO2 max. Physical activity seems to be feasible, safe, and effective for HD patients. However, further studies with longer follow-up and larger cohorts of patients will be needed to draw firm conclusions on the positive effects of exercise for HD patients.

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.

Huntington's disease influences employment before and during clinical manifestation: A systematic review

Huntington's disease (HD) is an inherited neurodegenerative disease. People at risk for HD can choose to get predictive testing years before the clinical onset. HD is characterized by motor, cognitive and psychiatric symptoms and has a mean age at onset between 30 and 50 years, an age at which people are usually still working. This systematic review focuses on summarizing which disease-specific characteristics influence employment and working capacity in HD. Twenty-three studies were identified and showed that while employment and working capacity in HD are negatively influenced by cognitive decline and motor impairments, apathy already plays a role in the prodromal stage. Moreover, the influence of HD transcends the clinical manifestation of the disease, as some people at risk are already experiencing the impact of HD on employment through fear of or actual genetic discrimination. Employment and working capacity are not influenced by predictive testing for HD in and of itself.

Perceived Effects of Neuropsychiatric Symptoms on Functional Status in Early-stage Huntington Disease

Neuropsychiatric symptoms in Huntington disease (HD) are commonly encountered, but their effects on functional status are poorly understood. In this qualitative study guided by the Theory of Unpleasant Symptoms, 15 HD patients and caregivers completed semi-structured interviews regarding perceived effects of neuropsychiatric symptoms on functional status. Physical, cognitive, and social functional effects were reported, with negative effects on daily activities and social withdrawal being reported by the greatest number of subjects. Participants also reported improved function with intervention for neuropsychiatric symptoms. This study provides a novel description of the lived experiences of HD patients with neuropsychiatric symptoms.

Cognitive Reserve in Early Manifest Huntington Disease Patients: Leisure Time Is Associated with Lower Cognitive and Functional Impairment

We focused on Cognitive Reserve (CR) in patients with early Huntington Disease (HD) and investigated whether clinical outcomes might be influenced by lifetime intellectual enrichment over time. CR was evaluated by means of the Cognitive Reserve Index questionnaire (CRIq), an internationally validated scale which includes three sections: education, working activity, and leisure time. The clinical HD variables were quantified at three different time points (baseline-t0, 1 year follow up-t1 and 2 years follow up-t2) as per the Unified Huntington’s Disease Rating Scale (UHDRS), an internationally standardized and validated scale including motor, cognitive, functional and behavioral assays. Our sample consisted of 75 early manifest patients, withclinical stage scored according to the Total Functional Capacity (TFC) scale. Our correlational analysis highlighted a significant inverse association between CRIq leisure time (CRIq_LA) and longitudinal functional impairment (namely, the differential TFC score between t2 and t0 or ΔTFC) (p < 0.05), and the multidimensional progression of HD as measured by the composite UHDRS (cUHDRS, p < 0.01). CRIq_LA was significantly and positively associated with better cognitive performances at all time points (p < 0.05). Our results suggest that higher is the CRIq_LA, milder is the progression of HD in terms of functional, multidimensional and cognitive outcome.

A Machine-Learning Derived Huntington's Disease Progression Model: Insights for Clinical Trial Design

BACKGROUND

Applying machine-learning algorithms to large datasets such as those available in Huntington's disease offers the opportunity to discover hidden patterns, often not discernible to clinical observation.

OBJECTIVES

To develop and validate a model of Huntington's disease progression using probabilistic machine learning methods.

METHODS

Longitudinal data encompassing 2079 assessment measures from four observational studies (PREDICT-HD, REGISTRY, TRACK-HD, and Enroll-HD) were integrated and machine-learning methods (Bayesian latent-variable analysis and continuous-time hidden Markov models) were applied to develop a probabilistic model of disease progression. The model was validated using a separate Enroll-HD dataset and compared with existing clinical reference assessments (Unified Huntington's Disease Rating Scale [UHDRS] diagnostic confidence level, total functional capacity, and total motor scores) and CAG-age product.

RESULTS

Nine disease states were discovered based on 44 motor, cognitive, and functional measures, which correlated with reference assessments. The validation set included 3158 participants (mean age, 48.4 years) of whom 61.5% had manifest disease. Analysis of transition times showed that "early-disease" states 1 and 2, which occur before motor diagnosis, lasted ~16 years. Increasing numbers of participants had motor onset during "transition" states 3 to 5, which collectively lasted ~10 years, and the "late-disease" states 6 to 9 also lasted ~10 years. The annual probability of conversion from one of the nine identified disease states to the next ranged from 5% to 27%.

CONCLUSIONS

The natural history of Huntington's disease can be described by nine disease states of increasing severity. The ability to derive characteristics of disease states and probabilities for progression through these states will improve trial design and participant selection. © 2021 International Parkinson and Movement Disorder Society.

Investigating Crosstalk Among PTMs Provides Novel Insight Into the Structural Basis Underlying the Differential Effects of Nt17 PTMs on Mutant Httex1 Aggregation

Post-translational modifications (PTMs) within the first 17 amino acids (Nt17) of the Huntingtin protein (Htt) have been shown to inhibit the aggregation and attenuate the toxicity of mutant Htt proteins in vitro and in various models of Huntington’s disease. Here, we expand on these studies by investigating the effect of methionine eight oxidation (oxM8) and its crosstalk with lysine 6 acetylation (AcK6) or threonine 3 phosphorylation (pT3) on the aggregation of mutant Httex1 (mHttex1). We show that M8 oxidation delays but does not inhibit the aggregation and has no effect on the final morphologies of mHttex1aggregates. The presence of both oxM8 and AcK6 resulted in dramatic inhibition of Httex1 fibrillization. Circular dichroism spectroscopy and molecular dynamics simulation studies show that PTMs that lower the mHttex1 aggregation rate (oxM8, AcK6/oxM8, pT3, pT3/oxM8, and pS13) result in increased population of a short N-terminal helix (first eight residues) in Nt17 or decreased abundance of other helical forms, including long helix and short C-terminal helix. PTMs that did not alter the aggregation rate (AcK6) of mHttex1 exhibit a similar distribution of helical conformation as the unmodified peptides. These results show that the relative abundance of N- vs. C-terminal helical conformations and long helices, rather than the overall helicity of Nt17, better explains the effect of different Nt17 PTMs on mHttex1; thus, explaining the lack of correlation between the effect of PTMs on the overall helicity of Nt17 and mHttex1 aggregation in vitro. Taken together, our results provide novel structural insight into the differential effects of single PTMs and crosstalk between different PTMs in regulating mHttex1 aggregation.

Huntington's Chorea-a Rare Neurodegenerative Autosomal Dominant Disease: Insight into Molecular Genetics, Prognosis and Diagnosis

Huntington's disease is a neurodegenerative autosomal disease results due to expansion of polymorphic CAG repeats in the huntingtin gene. Phosphorylation of the translation initiation factor 4E-BP results in the alteration of the translation control leading to unwanted protein synthesis and neuronal function. Consequences of mutant huntington (mhtt) gene transcription are not well known. Variability of age of onset is an important factor of Huntington's disease separating adult and juvenile types. The factors which are taken into account are-genetic modifiers, maternal protection i.e excessive paternal transmission, superior ageing genes and environmental threshold. A major focus has been given to the molecular pathogenesis which includes-motor disturbance, cognitive disturbance and neuropsychiatric disturbance. The diagnosis part has also been taken care of. This includes genetic testing and both primary and secondary symptoms. The present review also focuses on the genetics and pathology of Huntington's disease.

Cognitive and behavioral associated changes in manifest Huntington disease: A retrospective cross-sectional study

INTRODUCTION

Behavioral and cognitive changes can be observed across all Huntington disease (HD) stages. Our multicenter and retrospective study investigated the association between cognitive and behavioral scale scores in manifest HD, at three different yearly timepoints.

METHODS

We analyzed cognitive and behavioral domains by the Unified Huntington's Disease Rating Scale (UHDRS) and by the Problem Behaviors Assessment Short Form (PBA-s), at three different yearly times of life (t0 or baseline, t1 after one year, t2 after two years), in 97 patients with manifest HD (mean age 48.62 ± 13.1), from three ENROLL-HD Centers. In order to test the disease progression, we also examined patients' motor and functional changes by the UHDRS, overtime.

RESULTS

The severity of apathy and of perseveration/obsession was associated with the severity of the cognitive decline (p < .0001), regardless of the yearly timepoint. The score of irritability significantly and positively correlated with perseveration errors in the verbal fluency test at t0 (r = .34; p = .001), while the psychosis significantly and negatively correlated with the information processing speed at t0 (r = -.21; p = .038) and significantly and positively correlated with perseveration errors in the verbal fluency test at t1 (r = .35; p < .0001). The disease progression was confirmed by the significant worsening of the UHDRS-Total Motor Score (TMS) and of the UHDRS-Total Functional Capacity (TFC) scale score after two-year follow-up (p < .0001).

CONCLUSION

Although the progression of abnormal behavioral manifestations cannot be predicted in HD, the severity of apathy and perseveration/obsessions are significantly associated with the severity of the cognitive function impairment, thus contributing, together, to the disease development and to patients' loss of independence, in addition to the neurological manifestations. This cognitive-behavior pattern determines a common underlying deficit depending on a dysexecutive syndrome.

Responsiveness to Change Over Time: An Examination of the Neuro-QoL Social Function Measures in Persons with Huntington's Disease

BACKGROUND

Social health is an important concern in persons with Huntington's disease (HD); however, there is little literature examining this construct in this population.

OBJECTIVE

While cross-sectional data supports the clinical utility of two Neuro-QoL social health measures in persons with HD, data is still needed to establish their longitudinal validity.

METHODS

Participants (N = 358) completed baseline and at least one follow-up (12- and 24-month) assessment that included the completion of Neuro-QoL Social Health computer adaptive tests (CATs) and short forms (for Ability to Participate in Social Roles and Activities [SRA] and Satisfaction with SRA). Test-retest reliability was examined using intra class correlations, and one-way ANOVAs with Bonferroni post-hoc contrasts were used to determine whether there were group differences among premanifest, early- and late-stage HD participants on the Social health measures. In addition, standardized response means were used to examine longitudinal responsiveness, and mixed or general linear models were used to examine change over time (relative to self-reported change on an associated anchor item about social health and clinician-rated change based on Total Functional Capacity scores from the UHDRS).

RESULTS

Test-retest reliability of the measures was excellent (ICCs ranged from 0.82 to 0.87 across the different measures) and persons with greater disease burden reported more problems with social health than those at earlier stages in the disease process (all p < 0.0001). Responsiveness was supported for all measures except the Ability to Participate in SRA CAT; participants who had self-reported or clinician-rated declines in health generally had 12- and 24-month declines on the Neuro-QoL measures.

CONCLUSIONS

Findings indicate that these measures may be useful for studies attempting to assess change in social health over time.

Sex Differences in Huntington's Disease: Evaluating the Enroll-HD Database

BACKGROUND

Identifying sex-related differences is critical for enhancing our understanding of factors that may impact prognosis and advance treatments in Huntington's disease (HD).

OBJECTIVES

To investigate if sex-related differences exist in clinical HD.

METHODS

Longitudinal study of the Enroll-HD database. Manifest HD patients were included in the analysis (N = 8401). Linear mixed models were used to assess motor, behavioral, and cognitive functioning over a series of four annual visits, and compared male and female HD gene carriers.

RESULTS

HD patients showed significant sex-dependent differences in motor, cognitive, and behavioral symptoms. Both sexes had worsened motor symptoms over the course of four visits, but there was a significant disparity between sexes, with females consistently presenting with more symptoms than males. For behavioral symptoms, specifically depressive symptoms, females had significantly more depressive symptoms, although self-reported symptoms in both sexes became less severe throughout time.

CONCLUSIONS

Our analyses suggest that women have worse symptoms than men during the course of HD.

Proportional likelihood ratio mixed model for discrete longitudinal data

Rathouz and Gao [2] and Luo and Tsai [3] proposed valuable extensions to the generalized linear model for modeling a nonlinear monotonic relationship between the mean response and a set of covariates. In their extensions for discrete data the baseline response distribution is unspecified and is estimated from the data. We propose to extend this model for the analysis of longitudinal data by incorporating random effects into the linear predictor, and using maximum likelihood for estimation and inference. Motivated in particular by longitudinal studies of clinical scale outcomes, we developed an estimation procedure for a finite-support response using a generalized expectation-maximization algorithm where Gauss-Hermite quadrature is employed to approximate the integrals in the E step of the algorithm. Upon convergence, the observed information matrix is estimated through second-order numerical differentiation of the log-likelihood function. Asymptotic properties of the maximum likelihood estimates follow under the usual regularity conditions. Simulation studies are conducted to assess its finite-sample properties and compare the proposed model to the generalized linear mixed model. The proposed method is illustrated in an analysis of data from a longitudinal study of Huntington's disease.

A Novel Triplet-Primed PCR Assay to Detect the Full Range of Trinucleotide CAG Repeats in the Huntingtin Gene (HTT)

The expanded CAG repeat number in HTT gene causes Huntington disease (HD), which is a severe, dominant neurodegenerative illness. The accurate determination of the expanded allele size is crucial to confirm the genetic status in symptomatic and presymptomatic at-risk subjects and avoid genetic polymorphism-related false-negative diagnoses. Precise CAG repeat number determination is critical to discriminate the cutoff between unexpanded and intermediate mutable alleles (IAs, 27–35 CAG) as well as between IAs and pathological, low-penetrance alleles (i.e., 36–39 CAG repeats), and it is also critical to detect large repeat expansions causing pediatric HD variants. We analyzed the HTT-CAG repeat number of 14 DNA reference materials and of a DNA collection of 43 additional samples carrying unexpanded, IAs, low and complete penetrance alleles, including large (>60 repeats) and very large (>100 repeats) expansions using a novel triplet-primed PCR-based assay, the AmplideX PCR/CE HTT Kit. The results demonstrate that the method accurately genotypes both normal and expanded HTT-CAG repeat numbers and reveals previously undisclosed and very large CAG expansions >200 repeats. We also show that this technique can improve genetic test reliability and accuracy by detecting CAG expansions in samples with sequence variations within or adjacent to the repeat tract that cause allele drop-outs or inaccuracies using other PCR methods.

Known Drugs Identified by Structure-Based Virtual Screening Are Able to Bind Sigma-1 Receptor and Increase Growth of Huntington Disease Patient-Derived Cells

Huntington disease (HD) is a devastating and presently untreatable neurodegenerative disease characterized by progressively disabling motor and mental manifestations. The sigma-1 receptor (σ1R) is a protein expressed in the central nervous system, whose 3D structure has been recently determined by X-ray crystallography and whose agonists have been shown to have neuroprotective activity in neurodegenerative diseases. To identify therapeutic agents against HD, we have implemented a drug repositioning strategy consisting of: (i) Prediction of the ability of the FDA-approved drugs publicly available through the ZINC database to interact with σ1R by virtual screening, followed by computational docking and visual examination of the 20 highest scoring drugs; and (ii) Assessment of the ability of the six drugs selected by computational analyses to directly bind purified σ1R in vitro by Surface Plasmon Resonance and improve the growth of fibroblasts obtained from HD patients, which is significantly impaired with respect to control cells. All six of the selected drugs proved able to directly bind purified σ1R in vitro and improve the growth of HD cells from both or one HD patient. These results support the validity of the drug repositioning procedure implemented herein for the identification of new therapeutic tools against HD.

Significant Association Between Huntingtin Gene Mutation and Prevalence of Hopelessness, Depression and Anxiety Symptoms

SUMMARY BACKGROUND

In Huntington's disease psychiatric symptoms may manifest prior to motor dysfunction. Such symptoms negatively impact people's quality of life and can worsen the course of the primary disease. The aim of the present study was to assess and compare depression, anxiety and hopelessness rates in individuals with and without an abnormal expansion of CAG repeats in the huntingtin (HTT) gene and healthy controls.

MATERIALS AND METHODS

Study involved 31 individuals referred for genetic testing for Huntington's disease and a control group of 41. Depressive and anxiety symptoms were assessed using Beck Hopelessness Scale (BHS) and Hospital Anxiety and Depression Scale (HADS). Results between groups were compared using the Mann-Whitney U test. Two-sided Bonferroni corrected p-value was set at ≤0.017.

RESULTS

Individuals with HTT gene mutation ("gene mutation positive", GMP) (N=20) scored higher on the HADS depression subscale (5.90 ± 4.52 vs 1.36 ± 1.91; p ≤ 0.017) than those without HTT gene mutation ("gene mutation negative", GMN) (N=11). GMP and control groups scored higher than the GMN group on the BHS (5.65 ± 3.91 vs 2.09 ± 1.64 and 5.27 ± 4.11 vs 2.09 ± 1.64, respectively; p ≤ 0.017). No differences in anxiety levels were found.

CONCLUSIONS

Depressive symptoms and hopelessness were more prevalent in individuals with HTT gene mutation than in individuals who were tested but had no said mutation. Such results emphasise the importance of timely diagnosis and treatment of psychiatric comorbidities in individuals affected by Huntington's disease.

Site-Specific Phosphorylation of Huntingtin Exon 1 Recombinant Proteins Enabled by the Discovery of Novel Kinases

Post-translational modifications (PTMs) within the first 17 amino acids (Nt17) of exon 1 of the Huntingtin protein (Httex1) play important roles in modulating its cellular properties and functions in health and disease. In particular, phosphorylation of threonine and serine residues (T3, S13, and/or S16) has been shown to inhibit Htt aggregation in vitro and inclusion formation in cellular and animal models of Huntington's disease (HD). In this paper, we describe a new and simple methodology for producing milligram quantities of highly pure wild-type or mutant Httex1 proteins that are site-specifically phosphorylated at T3 or at both S13 and S16. This advance was enabled by 1) the discovery and validation of novel kinases that efficiently phosphorylate Httex1 at S13 and S16 (TBK1), at T3 (GCK) or T3 and S13 (TNIK and HGK), and 2) the development of an efficient methodology for producing recombinant native Httex1 proteins by using a SUMO-fusion expression and purification strategy.[26] As a proof of concept, we demonstrate how this method can be applied to produce Httex1 proteins that are both site-specifically phosphorylated and fluorescently or isotopically labeled. Together, these advances should increase access to these valuable tools and expand the range of methods and experimental approaches that can be used to elucidate the mechanisms by which phosphorylation influences Httex1 or HTT structure, aggregation, interactome, and function(s) in health and disease.

Understanding speech and swallowing difficulties in individuals with Huntington disease: Validation of the HDQLIFE Speech Difficulties and Swallowing Difficulties Item Banks

PURPOSE

As Huntington disease (HD) progresses, speech and swallowing difficulties become more profound. These difficulties have an adverse effect on health-related quality of life (HRQOL), thus psychometrically robust measures of speech and swallowing are needed to better understand the impact of these domains across the course of the disease. Therefore, the purpose of this study is to establish the clinical utility of two new patient-reported outcome measures (PROs), HDQLIFE Speech Difficulties and HDQLIFE Swallowing Difficulties.

METHODS

Thirty-one participants with premanifest or manifest HD, and 31 age- and sex-matched healthy control participants were recruited for this study. Participants completed several PROs [HDQLIFE Speech Difficulties, HDQLIFE Swallowing Difficulties, Communication Participation Item Bank (CPIB)], as well as several clinician-rated assessments of speech and functioning. A computational algorithm designed to detect features of spoken discourse was also examined. Analyses were focused on establishing the reliability and validity of these new measures.

RESULTS

Internal consistency was good for Swallowing (Cronbach's alpha = 0.89) and excellent for Speech and the CPIB (both Cronbach's alpha ≥ 0.94), and convergent/discriminant validity was supported. Known groups validity for the PROs was supported by significant group differences among control participants and persons with different stages of HD (all p < 0.0001). All PROs were able to distinguish those with and without clinician-rated dysarthria (likelihood ratios far exceeded the threshold for clinical decision making [all ≥ 3.28]).

CONCLUSIONS

Findings support the clinical utility of the HDQLIFE Speech and Swallowing PROs and the CPIB for use across the HD disease spectrum. These PROs also have the potential to be clinically useful in other populations.

Responsiveness to change over time and test-retest reliability of the PROMIS and Neuro-QoL mental health measures in persons with Huntington disease (HD)

BACKGROUND

The majority of persons with Huntington disease (HD) experience mental health symptoms. Patient-reported outcome (PRO) measures are capable of capturing unobservable behaviors and feelings relating to mental health. The current study aimed to test the reliability and responsiveness to self-reported and clinician-rated change over time of Neuro-QoL and PROMIS mental health PROs over the course of a 24-month period.

METHODS

At baseline, 12-months, and 24-months, 362 participants with premanifest or manifest HD completed the Neuro-QoL Depression computer adaptive test (CAT), PROMIS Depression short form (SF), Neuro-QoL Anxiety CAT, PROMIS Anxiety SF, PROMIS Anger CAT and SF, Neuro-QoL Emotional/Behavioral Dyscontrol CAT and SF, Neuro-QoL Positive Affect and Well-Being CAT and SF, and Neuro-QoL Stigma CAT and SF. Participants completed several clinician-administered measures at each time point, as well as several global ratings of change at 12- and 24-months. Reliability (test-retest reliability and measurement error) and responsiveness (using standardized response means and general linear models) were assessed.

RESULTS

Test-retest reliability and measurement error were excellent for all PROs (all ICC ≥ .90 for test-retest reliability and all SEM percentages ≤ 6.82%). In addition, 12- and 24-month responsiveness were generally supported for the Neuro-QoL and PROMIS mental health PROs; findings relative to clinician-rated anchors of change (e.g., SRMs for the group with declines ranged from .38 to .91 for 24-month change and .09 to .45, with the majority above .25 for 12-month change) were generally more robust than those relative to self-reported anchors of change (e.g., SRMs for the group with declines ranged from .02 to .75, with the majority above .39 for 24-month change and .09 to .45, with the majority above .16 for 12-month change).

CONCLUSIONS

The Neuro-QoL and PROMIS mental health PROs demonstrated strong psychometric reliability, as well as responsiveness to self-reported and clinician-rated change over time in people with HD.

A Systematic Review of Neuropsychiatric Symptoms and Functional Capacity in Huntington's Disease

OBJECTIVE

Neuropsychiatric symptoms are known to increase caregiver burden and decrease patient quality of life among patients with Huntington's disease. Functional capacity is an outcome commonly used in Huntington's disease clinical trials to quantify disease progression or intervention response. Some studies have examined the relationship between neuropsychiatric symptoms and functional capacity; however, this evidence has not been synthesized. The authors reviewed existing evidence on the association between neuropsychiatric symptoms and functional capacity in Huntington's disease.

METHODS

A systematic review was conducted using PubMed and CINAHL. Articles were included if they described primary research in humans with Huntington's disease, measured one or more neuropsychiatric symptoms and functional capacity, and reported statistical methods to identify associations between the two concepts. Additional eligible articles were identified through reference mining and review of other relevant literature.

RESULTS

Fourteen articles were eligible for review. Neuropsychiatric symptoms were measured individually, in clusters (i.e., depression, anxiety, and suicide items contributing to a depression cluster score), or with an overall score. Significant associations with decreased functional capacity were found most commonly with depression (N=7, median r=0.48) and apathy (N=5, median r=0.47). Other neuropsychiatric symptoms, clusters, and overall scores were all associated with functional capacity in three or fewer studies.

CONCLUSIONS

There is some evidence that depression and apathy are associated with decreased functional capacity in Huntington's disease. Other neuropsychiatric symptoms have been infrequently examined. Further knowledge of the relationships between neuropsychiatric symptoms and functional capacity will identify areas for intervention and improvement of outcomes in patients with Huntington's disease.

Classification of Manifest Huntington Disease using Vowel Distortion Measures

Huntington disease (HD) is a fatal autosomal dominant neurocognitive disorder that causes cognitive disturbances, neuropsychiatric symptoms, and impaired motor abilities (e.g., gait, speech, voice). Due to its progressive nature, HD treatment requires ongoing clinical monitoring of symptoms. Individuals with the Huntingtin gene mutation, which causes HD, may exhibit a range of speech symptoms as they progress from premanifest to manifest HD. Speech-based passive monitoring has the potential to augment clinical information by more continuously tracking manifestation symptoms. Differentiating between premanifest and manifest HD is an important yet under-studied problem, as this distinction marks the need for increased treatment. In this work we present the first demonstration of how changes in speech can be measured to differentiate between premanifest and manifest HD. To do so, we focus on one speech symptom of HD: distorted vowels. We introduce a set of Filtered Vowel Distortion Measures (FVDM) which we extract from read speech. We show that FVDM, coupled with features from existing literature, can differentiate between premanifest and manifest HD with 80% accuracy.

[Gene-selective treatment approaches for Huntington's disease]

In Germany at least 8000 and probably up to ca. 14,000 people currently suffer from clinically manifest Huntington's disease (HD). In addition, an estimated 24,000 Germans carry the HD mutation in the huntingtin (HTT) gene and will develop HD during their lifetime. Although HD is a rare neurodegenerative disease, it is currently in the focus of general medical interest: clinical trials have begun that provide a rational basis for hope to slow down the so far relentless progression of the disease, ultimately resulting in patients becoming entirely dependent on nursing care. If treatment is started early enough it may be possible to mitigate the clinical manifestation of HD. These innovative therapeutic approaches aim at inhibiting the de novo production of mutant HTT gene products. A first clinical drug trial to demonstrate the efficacy (phase III) of intrathecal antisense oligonucleotides (ASO, active substance RG6042) was started in 2019. Additional clinical studies on alternative treatment approaches with allele-selective ASOs as well as gene therapeutic approaches using RNA molecules and zinc finger repressor complexes are imminent. This article gives an overview of the current gene-selective therapeutic approaches in HD under discussion.

Validation of Neuro-QoL and PROMIS Mental Health Patient Reported Outcome Measures in Persons with Huntington Disease

BACKGROUND

Patient-reported outcomes (PROs) for mental health are important for persons with Huntington disease (HD) who commonly experience symptoms of depression, anxiety, irritability, anger, aggression, and apathy. Given this, there is a need for reliable and valid patient-reported outcomes measures of mental health for use as patient-centered outcomes in clinical trials.

OBJECTIVE

Thus, the purpose of this study was to establish the psychometric properties (i.e., reliability and validity) of six Neuro-QoL and PROMIS mental health measures to support their clinical utility in persons with HD.

METHODS

294 individuals with premanifest (n = 102) or manifest HD (n = 131 early HD; n = 61 late HD) completed Neuro-QoL/PROMIS measures of Emotional and Behavioral Dyscontrol, Positive Affect and Well-Being, Stigma, Anger, Anxiety, and Depression, legacy measures of self-reported mental health, and clinician-rated assessments of functioning.

RESULTS

Convergent validity and discriminant validity for the Neuro-QoL and PROMIS measures of Emotional and Behavioral Dyscontrol, Positive Affect and Well-Being, Stigma, Anger, Anxiety, and Depression, were supported in persons with HD. Neuro-QoL measures of Anxiety and Depression also demonstrated moderate sensitivity and specificity (i.e., they were able to distinguish between individuals with and without clinically significant anxiety and depression).

CONCLUSIONS

Findings provide psychometric support for the clinical utility of the Neuro-QoL/PROMIS measures of mental health measures in persons with HD. As such, these measures should be considered for the standardized assessment of health-related quality of life in persons with HD.

Daily functioning and dementia

Dementia is characterized by a decline in memory, language, problem-solving and in other cognitive domains that affect a person's ability to perform everyday activities and social functioning. It is consistently agreed that cognitive impairment is an important risk factor for developing functional disabilities in patients with dementia. Functional status can be conceptualized as the ability to perform self-care, self- maintenance and physical activity. A person with dementia usually requires help with more complex tasks, such as managing bills and finances, or simply maintaining a household. Good functional performance is fundamental for elderly people to maintain independency and avoid institutionalization. The purpose of this review is to describe functional changes in demented patients, evaluating the variability in subgroups of dementias.

Psychiatric morbidity and poor follow-up underlie suboptimal functional and survival outcomes in Huntington's disease

Background

Huntington’s disease (HD), an inherited, often late-onset, neurodegenerative disorder, is considered to be a rare, orphan disease. Research into its genetic correlates and services for those affected are inadequate in most low-middle income countries, including India. The apparent ‘incurability’ often deters symptomatic and rehabilitative care, resulting in poor quality of life and sub-optimal outcomes. There are no studies assessing disease burden and outcomes from India.

Methods

We attempted to evaluate individuals diagnosed to have HD at our tertiary-care center between 2013 and 2016 for clinical symptoms, functionality, mortality, follow up status through a structured interview, clinical data from medical records and UHDRS-TFC scoring.

Results

Of the 144 patients, 25% were untraceable, and another 17 (11.8%) had already died. Mean age at death and duration of illness at the time of death, were 53 years and 7 years respectively, perhaps due to suicides and other comorbidities at an early age. The patients who could be contacted (n = 81) were assessed for morbidity and total functional capacity (TFC). Mean CAG repeat length and TFC score were 44.2 and 7.5 respectively. Most individuals (66%) were in TFC stage I and II and could perhaps benefit from several interventions. The TFC score correlated inversely with duration of illness (p < 0.0001). The majority were being taken care of at home, irrespective of the physical and mental disability. There was a high prevalence of psychiatric morbidity (91%) including suicidal tendency (22%). Three of the 17 who died had committed suicide, and several other families reported suicidal history in other family members. Only about half the patients (57%) maintained a regular clinical follow-up.

Conclusions

This study demonstrates the poor follow-up rates, significant suicidality and other psychiatric symptoms, sub-optimal survival durations and functional outcomes highlighting the need for holistic care for the majority who appear to be amenable to interventions.

Emotion recognition and inhibitory control in manifest and pre-manifest Huntington's disease: evidence from a new Stroop task

Huntington's disease (HD) is a genetic neurodegenerative disorder that affects not only the motor but also the cognitive domain. In particular, cognitive symptoms such as impaired executive skills and deficits in recognizing other individuals' mental state may emerge many years before the motor symptoms. This study was aimed at testing two cognitive hypotheses suggested by previous research with a new Stroop task created for the purpose: 1) the impairment of emotion recognition in HD is moderated by the emotions' valence, and 2) inhibitory control is impaired in HD. Forty manifest and 20 pre-manifest HD patients and their age- and gender-matched controls completed both the traditional "Stroop Color and Word Test" (SCWT) and the newly created "Stroop Emotion Recognition under Word Interference Task" (SERWIT), which consist in 120 photographs of sad, calm, or happy faces with either congruent or incongruent word interference. On the SERWIT, impaired emotion recognition in manifest HD was moderated by emotion type, with deficits being larger in recognizing sadness and calmness than in recognizing happiness, but it was not moderated by stimulus congruency. On the SCWT, six different interference scores yielded as many different patterns of group effects. Overall our results corroborate the hypothesis that impaired emotion recognition in HD is moderated by the emotions' valence, but do not provide evidence for the hypothesis that inhibitory control is impaired in HD. Further research is needed to learn more about the psychological mechanisms underlying the moderating effect of emotional valence on impaired emotion recognition in HD, and to corroborate the hypothesis that the inhibitory processes involved in Stroop tasks are not impaired in HD. Looking beyond this study, the SERWIT promises to make important contributions to disentangling the cognitive and the psychomotor aspects of neurological disorders. The research was approved by the Ethics Committee of the "Istituto Leonarda Vaccari", Rome on January 24, 2018.

Keeping People with Dementia or Mild Cognitive Impairment in Employment: A Literature Review on Its Determinants

Background: Approximately 10–20% of people with early onset dementias (EOD) or mild cognitive impairment (MCI) are aged under 65 and, due to extended working life and increasing prevalence of dementias, they more and more frequently will be present in the active workforce. This review aimed to synthesize the available information about the ability of people with EOD or MCI to retain their participation in the labor workforce. Methods: We searched SCOPUS and EMBASE for peer-reviewed papers that reported studies assessing work ability in employees with EOD or MCI that were published in the period of January 2010 to August 2019. Results: We selected four publications, in which 1012 participants with EOD or MCI were enrolled (41.2% males). Cognitive difficulties rather than motor dysfunction were found to reduce patients’ ability to work. Two main themes emerged: management of dementia in the workplace and the impact of symptoms on working status. Conclusions: EOD and MCI impact on workforce participation by determining problems in executive functions. Although this review was based on a small sample of studies, it can be shown that support in the workplace may act as a facilitator to enhance workforce participation, and occupational health professionals can help patients with EOD or MCI continue working as much as possible.

Baseline Variables Associated with Functional Decline in 2CARE, A Randomized Clinical Trial in Huntington's Disease

BACKGROUND

Despite the clearly recognized progressive functional decline of Huntington's disease (HD), detailed investigations of factors associated with the rate of functional progression are limited.

OBJECTIVE

Understanding factors associated with functional decline through examination of existing HD clinical databases may improve efforts to mitigate it.

METHODS

We analyzed data from 2CARE, a randomized clinical trial with up to 5 years of follow-up, to assess potential risk factors for more rapid functional decline in HD.

RESULTS

Variables associated with faster functional decline included worse motor performance, worse cognitive test scores, female sex, lower weight and body mass index, and a higher CAG repeat length, especially in younger people.

CONCLUSION

While our data are limited to the structured environment and homogeneity of a clinical trial, attention to several of the identified risk factors may be useful towards managing functional decline over time. The observation that women progress faster than men, while potentially confounded by an association between sex and weight, deserves further study.

Effects of Pridopidine on Functional Capacity in Early-Stage Participants from the PRIDE-HD Study

BACKGROUND

No pharmacological treatment has been demonstrated to provide a functional benefit for persons with Huntington's disease (HD). Pridopidine is a sigma-1-receptor agonist shown to have beneficial effects in preclinical models of HD.

OBJECTIVE

To further explore the effect of pridopidine on Total Functional Capacity (TFC) in the recent double-blind, placebo-controlled PRIDE-HD study.

METHODS

We performed post-hoc analyses to evaluate the effect of pridopidine on TFC at 26 and 52 weeks. Participants were stratified according to baseline TFC score and analyzed using repeated measures (MMRM) and multiple imputation assuming missing not-at-random (MNAR) and worst-case scenarios.

RESULTS

The pridopidine 45 mg bid dosage demonstrated a beneficial effect on TFC for the entire population at week 52 of 0.87 (nominal p = 0.0032). The effect was more pronounced for early HD participants (HD1/HD2, TFC = 7-13), with a change from placebo of 1.16 (nominal p = 0.0003). This effect remained nominally significant using multiple imputation with missing not at random assumption as a sensitivity analysis. Responder analyses showed pridopidine 45 mg bid reduced the probability of TFC decline in early HD patients at Week 52 (nominal p = 0.02).

CONCLUSION

Pridopidine 45 mg bid results in a nominally significant reduction in TFC decline at 52 weeks compared to placebo, particularly in patients with early-stage HD.

Psychometric properties and responsiveness of Neuro-QoL Cognitive Function in persons with Huntington disease (HD)

PURPOSE

Individuals with Huntington disease (HD) experience progressive cognitive decline that may appear years before motor manifestations of the disease. These declines have a profound effect on health-related quality of life (HRQOL) over the disease course, and thus it is important that self-report measures of cognitive function are validated for use in longitudinal studies.

METHODS

359 individuals with premanifest or manifest HD completed baseline and at least one follow-up (12- and 24-month) assessment. Neuro-QoL™ Cognitive Function was administered at each time-point. Participants completed a self-reported global rating of cognitive change, as well as performance-based cognitive changes (using the Symbol Digit Modalities Test). Standardized response means (SRMs) and general linear models evaluated whether Neuro-QoL™ Cognitive Function was responsive to change over time with respect to self-reported and performance-based anchors. Test-retest reliability and known-group validity were also examined.

RESULTS

Responsiveness was supported by effect sizes that were small in magnitude, but in the expected direction relative to self-reported and performance-based change. General linear models generally supported 12- and 24-month responsiveness relative to self-reported cognitive change and 12-month responsiveness relative to performance-based change. Test-retest reliability was excellent, and the measure exhibited known-group validity.

CONCLUSION

Longitudinal analyses generally indicate that the Neuro-QoL™ Cognitive Function measure is sensitive to change over time in individuals with HD. Neuro-QoL Cognitive Function changes reflect self-reported cognitive change at 12 and 24 months and performance-based change at 12 months. This measure may be useful in clinical trials or longitudinal observation studies.

HDQLIFE and neuro-QoL physical function measures: Responsiveness in persons with huntington's disease

BACKGROUND

Huntington's disease (HD) is a neurological disorder that causes severe motor symptoms that adversely impact health-related quality of life. Patient-reported physical function outcome measures in HD have shown cross-sectional evidence of validity, but responsiveness has not yet been assessed.

OBJECTIVES

This study evaluates the responsiveness of the Huntington Disease Health-Related Quality of Life (HDQLIFE) and the Quality of Life in Neurological Disorders (Neuro-QoL) physical function measures in persons with HD.

METHODS

A total of 347 participants completed baseline and at least 1 follow-up (12-month and 24-month) measure (HDQLIFE Chorea, HDQLIFE Swallowing Difficulties, HDQLIFE Speech Difficulties, Neuro-QoL Upper Extremity Function, and/or Neuro-QoL Lower Extremity Function). Of the participants that completed the baseline assessment, 338 (90.9%) completed the 12-month assessment, and 293 (78.8%) completed the 24-month assessment. Standardized response means and general linear models evaluated whether the physical function measures were responsive to self-reported and clinician-rated change over time.

RESULTS

Small to moderate effect sizes for the standardized response means supported 12-month and 24-month responsiveness of the HDQLIFE and Neuro-QoL measures for those with either self-reported or clinician-rated declines in function. General linear models supported 12-month and 24-month responsiveness for all HRQOL measures relative to self-reported declines in health, but generally only 24-month responsiveness was supported relative to clinician-rated declines in function.

CONCLUSIONS

Longitudinal analyses indicate that the HDQLIFE and the Neuro-QoL physical function measures are sensitive to change over time in individuals with HD. Thus, these scales exhibit evidence of responsiveness and may be useful outcome measures in future clinical trials. © 2019 International Parkinson and Movement Disorder Society.

How different aspects of motor dysfunction influence day-to-day function in huntington's disease

PURPOSE

This study examined the relationships between different aspects of motor dysfunction (chorea, dystonia, rigidity, incoordination, oculomotor dysfunction, dysarthria, and gait difficulties) and functional status in persons with Huntington's disease.

METHODS

A total of 527 persons with Huntington's disease completed the Unified Huntington's Disease Rating Scale motor, total functional capacity, and functional assessments.

RESULTS

Confirmatory factor analysis indicated that a 4-factor model provided a better model fit than the existing 5-factor model. Exploratory factor analysis identified the following 4 factors from the motor scale: dystonia, chorea, rigidity, and a general motor factor. Regression indicated that dystonia (β = -0.47 and -0.79) and rigidity (β = -0.28 and -0.59) had strong associations with function, whereas chorea had modest correlations (β = -0.16 and -0.15).

CONCLUSIONS

Dystonia and rigidity have stronger relationships with functional status than chorea in persons with Huntington's disease. The findings underscore the need for further research regarding the effects of dystonia and rigidity on functioning. © 2019 International Parkinson and Movement Disorder Society.

Pridopidine: Overview of Pharmacology and Rationale for its Use in Huntington's Disease

Despite advances in understanding the pathophysiology of Huntington’s disease (HD), there are currently no effective pharmacological agents available to treat core symptoms or to stop or prevent the progression of this hereditary neurodegenerative disorder. Pridopidine, a novel small molecule compound, has demonstrated potential for both symptomatic treatment and disease modifying effects in HD. While pridopidine failed to achieve its primary efficacy outcomes (Modified motor score) in two trials (MermaiHD and HART) there were consistent effects on secondary outcomes (TMS). In the most recent study (PrideHD) pridiopidine did not differ from placebo on TMS, possibly due to a large enduring placebo effect.

This review describes the process, based on in vivo systems response profiling, by which pridopidine was discovered and discusses its pharmacological profile, aiming to provide a model for the system-level effects, and a rationale for the use of pridopidine in patients affected by HD. Considering the effects on brain neurochemistry, gene expression and behaviour in vivo, pridopidine displays a unique effect profile. A hallmark feature in the behavioural pharmacology of pridopidine is its state-dependent inhibition or activation of dopamine-dependent psychomotor functions. Such effects are paralleled by strengthening of synaptic connectivity in cortico-striatal pathways suggesting pridopidine has potential to modify phenotypic expression as well as progression of HD. The preclinical pharmacological profile is discussed with respect to the clinical results for pridopidine, and proposals are made for further investigation, including preclinical and clinical studies addressing disease progression and effects at different stages of HD.