Early Stage Huntington's Disease Research Articles

Impaired striatal glutathione-ascorbate metabolism induces transient dopamine increase and motor dysfunction.

Identifying initial triggering events in neurodegenerative disorders is critical to developing preventive therapies. In Huntington's disease (HD), hyperdopaminergia-probably triggered by the dysfunction of the most affected neurons, indirect pathway spiny projection neurons (iSPNs)-is believed to induce hyperkinesia, an early stage HD symptom. However, how this change arises and contributes to HD pathogenesis is unclear. Here, we demonstrate that genetic disruption of iSPNs function by Ntrk2/Trkb deletion in mice results in increased striatal dopamine and midbrain dopaminergic neurons, preceding hyperkinetic dysfunction. Transcriptomic analysis of iSPNs at the pre-symptomatic stage showed de-regulation of metabolic pathways, including upregulation of Gsto2, encoding glutathione S-transferase omega-2 (GSTO2). Selectively reducing Gsto2 in iSPNs in vivo effectively prevented dopaminergic dysfunction and halted the onset and progression of hyperkinetic symptoms. This study uncovers a functional link between altered iSPN BDNF-TrkB signalling, glutathione-ascorbate metabolism and hyperdopaminergic state, underscoring the vital role of GSTO2 in maintaining dopamine balance.

Rasch Measurement Theory (RMT) Analyses of the Huntington's Disease Everyday Functioning (Hi-DEF) to Evaluate Item Fit and Performance.

The Huntington's Disease (HD) Everyday Functioning (Hi-DEF) is a new patient-reported outcome (PRO) instrument designed to measure the impact of cognitive impairment on daily functioning in the early stages of HD. To assess the measurement properties and finalize item content of the Hi-DEF. A cross-sectional, observational psychometric validation study was conducted among individuals with early stages of HD at 9 US centers of excellence. Rasch Measurement Theory (RMT) analysis of the initial draft version of the Hi-DEF (47 items) and subscales (i.e., 'Home', 'At work', 'Driving', and 'Communication') was conducted to examine measurement properties including sample-to-scale targeting, suitability of response scale (ordering of response thresholds), scale cohesiveness (item fit), local independence, and person fit. 151 participants (mean age 47 years (SD 12), 59% female) were included. Seven items were removed based on dependency and item fit. The remaining 40-item version of the Hi-DEF demonstrated good measurement properties. Across the four subscales, targeting ranged from 49-70% (72% full scale), reliability ascertained by person separation index ranged from 0.53-0.87 (0.92 full scale), response scales were ordered for 25-100% of items (75% full scale), 0-12% items displayed misfit (2% full scale), and 0-1% (2% full scale) item pairs displayed dependency. Our study supports the psychometric integrity of the Hi-DEF as a reliable and valid new PRO instrument designed to assess the impact of cognitive impairment on daily functioning in the early stages of HD. Future work will evaluate the external validity and utility in clinical trial applications.

White Matter Microstructure Changes Revealed by Diffusion Kurtosis and Diffusion Tensor Imaging in Mutant Huntingtin Gene Carriers.

Diffusion magnetic resonance imaging (dMRI) has revealed microstructural changes in white matter (WM) in Huntington's disease (HD). To compare the validities of different dMRI, i.e., diffusion kurtosis imaging (DKI) and diffusion tensor imaging (DTI) in HD. 22 mutant huntingtin (mHTT) carriers and 14 controls were enrolled. Clinical assessments and dMRI were conducted. Based on CAG-Age Product (CAP) score, mHTT carriers were categorized into high CAP (hCAP) and medium and low CAP (m& lCAP) groups. Spearman analyses were used to explore correlations between imaging parameters in brain regions and clinical assessments. Receiver operating characteristic (ROC) was used to distinguish mHTT carriers from control, and define the HD patients at advanced stage. Compared to controls, mHTT carriers exhibited WM changes in DKI and DTI. There were 22 more regions showing significant differences in HD detected by MK than FA. Only MK in five brain regions showed significantly difference between any two group, and negatively correlated with the disease burden (r = -0.80 to -0.71). ROC analysis revealed that MK was more sensitive and FA was more specific, while Youden index showed that the integration of FA and MK gave rise to higher authenticities, in distinguishing m& lCAP from controls (Youden Index = 0.786), and discerning different phase of HD (Youden Index = 0.804). Microstructural changes in WM occur at early stage of HD and deteriorate over the disease progression. Integrating DKI and DTI would provide the best accuracies for differentiating early HD from control and identifying advanced HD.

Virtual reality tolerability, sense of presence and usability in Huntington disease: a pilot study.

Several studies demonstrated the utility of immersive virtual reality (VR) as a complementary approach to conventional therapy for improving motor, psychological and cognitive impairment in some pathological conditions. Our pilot study aims to evaluate for the first time: 1) sense of presence, tolerability and usability of VR immersive experience in patients with early stages of Huntington disease (eHDp) compared to healthy controls (HC); 2) correlation between the use of technology/cybersickness and the variables of presence/usability; 3) correlation between clinical characteristics (genetic, motor, functional and cognitive) and VR's variables. We recruited 10 eHDp and 10 age, gender and education matched HC. Participants completed questionnaires about sense of presence, usability, tolerability and technology use profile. Subjects were exposed to different VR scenarios from a first-person perspective through a standalone VR headset. Our results showed no significant statistical difference between eHDp and HC for the sense of presence (p=0.910), usability (p=0.744) and tolerability (p=0.730) during the VR experience. Familiarity with the use of technology was also comparable between groups (p=0.676). Regarding correlations in eHDp group, our results showed no correlations between use of technology/tolerability and the sense of presence/usability. Moreover, clinical characteristics of eHDp (genetic, motor, functional and cognitive scores) did not influence the sense of presence, tolerability and usability. Our research presents preliminary evidence for the applicability of VR in eHDp. These results open up the possibility to explore future applications of this methodology in rehabilitation (i.e., cognitive training, physiotherapy), diagnosis and psychological support in Huntington disease patients.

Associations of inflammatory cytokines and cortisol with nonmotor features of Huntington's disease.

Huntington's disease (HD) is an inherited neurodegenerative disease involving progressive motor abnormalities, cognitive decline, and psychiatric disturbances. Depression and cognitive difficulties are among the most impactful symptoms of HD, yet the pathogenesis of these symptoms is not fully understood. HD involves low-level chronic inflammation and dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis, which are linked to depression and cognitive impairment in non-HD populations. However, previous research on the relationships of these pathologies with depression and cognition in HD is limited and inconsistent. Fifty-three adults with the HD gene expansion (30 premanifest and 23 manifest) completed measures of depression and cognitive functioning. Forty-eight out of 53 participants provided hair samples for quantification of cortisol, and 34 participants provided blood samples for quantification of peripheral inflammatory cytokines. We examined the associations of four cytokines (interleukin [IL]-6, IL-10, IL-1β, and tumor necrosis factor [TNF]-α) and cortisol levels with depression and cognitive scores. In unadjusted models, higher levels of plasma IL-6, IL-10, and TNF-α correlated with higher depression scores, and higher levels of IL-10 and TNF-α correlated with poorer cognitive performance. After controlling for age, sex, and body mass index, only the correlations of IL-10 with depression and cognitive performance remained significant. No correlations were evident with hair cortisol. Peripheral inflammation is associated with depression symptoms and cognitive impairment in HD. Our findings suggest that interactions between the immune and nervous systems are important in HD, and highlight the potential of chronic inflammation as a therapeutic target in early stages of HD.

Economic Burden of Huntington’s Disease in China: Results from a National-Wide Cross-Sectional Study

Background: Huntington’s disease (HD) poses a significant socio-economic burden globally. Existing research on HD’s economic burden predominantly comes from Western settings, leaving a gap in data from Asian countries. This study aimed to assess the economic burden of HD in China and identify cost-driving factors. Methods: This study used data from a 2019 nationwide cross-sectional survey of individuals affected by rare diseases in China. Data included socio-demographic characteristics, income, disease stage, health and social insurance coverage status, treatment-seeking behaviour, and costs. Logistic regression and linear regression were used to explore potential contributors to treatment-seeking behaviour and associated costs. Results: Of the 269 individuals with HD included in this study, 80.6% were actively seeking treatment. The average annual direct medical cost, direct non-medical cost, and indirect cost were 3,265.65, 805.82, and 801.97 Euros, respectively. Compared to participants with early-stage HD, those with middle- or advanced-stage HD reported higher direct medical costs (coefficient 1,612.70, 95% confidence interval [CI]: [141.92, 3,083.48] and 2,398.58, 95% CI: [791.16, 4,006.00], respectively). However, the disease stage was not significantly associated with direct non-medical costs or indirect costs. Conclusions: This study provides crucial insights into the economic burden of HD in China. It emphasises a need for targeted policies that better cater to the financial needs of HD patients.

Environmental Deprivation Effects on Myelin Ultrastructure in Huntington Disease and Wildtype Mice.

Environmental deprivation can have deleterious effects on adaptive myelination and oligodendroglia function. Early stage Huntington disease (HD) is characterised by white-matter myelin abnormalities in both humans and animal models. However, whether deprived environments exacerbate myelin-related pathological features of HD is not clearly understood. Here, we investigated the impact of deprivation and social isolation on ultrastructural features of myelin in the corpus callosum of the YAC128 mouse model of HD and wildtype (WT) mice using transmission electron microscopy. HD pathology on its own leads to increased representation of altered myelin features, such as thinner sheaths and compromised morphology. Interestingly, deprivation mirrors these effects in WT mice but does not greatly exacerbate the already aberrant myelin in HD mice, indicating a disease-related floor effect in the latter animals. These novel findings indicate that environmental deprivation causes abnormalities in myelin ultrastructure in the otherwise healthy corpus callosum of wild-type mice but has distinct effects on HD mice, where compromised myelin integrity is manifest from early stages of the disease.

59 Preliminary Findings of Semantic Interference in Learning and Memory Processes in Manifest Huntington’s Disease

Objective:To explore the usefulness of the Lowenstein-Acevedo Scales for Semantic Interference and Learning (LASSI-L) [Crocco et al, 2013], a novel memory-based cognitive stress test capitalizing on semantic interference, in Huntington’s Disease (HD).Participants and Methods:12 healthy adults (HA) and 14 individuals with manifest HD were administered the LASSI-L as part of an annual research visit with the UCSD Huntington’s Disease Clinical Research Center (HDCRC.) Participants in each group were well matched with regard to age and education. Individuals with manifest HD had an average MoCA score of 26, total functional capacity score of 10, and total motor score of 21 suggesting that they were in the early stages of HD. The LASSI-L examines different types of semantic interference that occur in the learning/encoding process. There are free and cued recall trials for two lists of semantically related words with certain trials specific to different aspects of semantic interference including proactive, retroactive, and failure to recover from proactive interference. T-tests for all recall trials and number of intrusions for each trial were conducted between HA and those with HD to examine whether HD renders one more prone to semantic interference in both encoding and retrieval memory processes.Results:Individuals with HD recalled fewer words on average than HA across all recall trials except for the initial free recall of the first word list. HD individuals recalled significantly fewer (∼1.5) words during the initial (t=-2.8, p=.005, Cohen’s d=2.7) and secondary (t=-2.9, p=.003, Cohen’s d=2.6) cued recall trials from the words on the first list. Individuals with HD also recalled significantly fewer words on initial free recall (t=-2.9, p=.003, Cohen’s d=2.6) and cued recall trials of the second list, with the initial cued recall (t=-2.8, p=.005, Cohen’s d=3.1) sensitive to proactive semantic interference and the second cued recall (t=-3.3, p=.001, Cohen’s d=2.6) sensitive to failure to recover from proactive semantic interference. In addition, individuals with HD also recalled significantly fewer (∼2.2) words on delayed cued recall of the first list, a measure of retroactive semantic interference, than HA (t=-4.8, p<.001, Cohen’s d=2.4). Lastly, individuals with HD recalled fewer (∼4.1) words than HA on delayed free recall of both word lists (t=-3.5, p<.001, Cohen’s d=5.9). The groups did not differ significantly with regard to number of total intrusions per trial.Conclusions:Overall, our study supports the usefulness of the LASSI-L for neuropsychological assessment of HD in clinical and research settings. In comparison to a demographically similar group of HA, individuals with manifest HD showed significant differences in frontally mediated retrieval processes as well as semantic interference processes that affect efficient encoding of novel information.

Altered exocytosis of inhibitory synaptic vesicles at single presynaptic terminals of cultured striatal neurons in a knock-in mouse model of Huntington's disease.

Huntington's disease (HD) is a progressive dominantly inherited neurodegenerative disease caused by the expansion of a cytosine-adenine-guanine (CAG) trinucleotide repeat in the huntingtin gene, which encodes the mutant huntingtin protein containing an expanded polyglutamine tract. One of neuropathologic hallmarks of HD is selective degeneration in the striatum. Mechanisms underlying selective neurodegeneration in the striatum of HD remain elusive. Neurodegeneration is suggested to be preceded by abnormal synaptic transmission at the early stage of HD. However, how mutant huntingtin protein affects synaptic vesicle exocytosis at single presynaptic terminals of HD striatal neurons is poorly understood. Here, we measured synaptic vesicle exocytosis at single presynaptic terminals of cultured striatal neurons (mainly inhibitory neurons) in a knock-in mouse model of HD (zQ175) during electrical field stimulation using real-time imaging of FM 1-43 (a lipophilic dye). We found a significant decrease in bouton density and exocytosis of synaptic vesicles at single presynaptic terminals in cultured striatal neurons. Real-time imaging of VGAT-CypHer5E (a pH sensitive dye conjugated to an antibody against vesicular GABA transporter (VGAT)) for inhibitory synaptic vesicles revealed a reduction in bouton density and exocytosis of inhibitory synaptic vesicles at single presynaptic terminals of HD striatal neurons. Thus, our results suggest that the mutant huntingtin protein decreases bouton density and exocytosis of inhibitory synaptic vesicles at single presynaptic terminals of striatal neurons, causing impaired inhibitory synaptic transmission, eventually leading to the neurodegeneration in the striatum of HD.

Transcriptional and Histone Acetylation Changes Associated with CRE Elements Expose Key Factors Governing the Regulatory Circuit in the Early Stage of Huntington's Disease Models.

Huntington's disease (HD) is a disorder caused by an abnormal expansion of trinucleotide CAG repeats within the huntingtin (Htt) gene. Under normal conditions, the CREB Binding Protein interacts with CREB elements and acetylates Lysine 27 of Histone 3 to direct the expression of several genes. However, mutant Htt causes depletion of CBP, which in turn induces altered histone acetylation patterns and transcriptional deregulation. Here, we have studied a differential expression analysis and H3K27ac variation in 4- and 6-week-old R6/2 mice as a model of juvenile HD. The analysis of differential gene expression and acetylation levels were integrated into Gene Regulatory Networks revealing key regulators involved in the altered transcription cascade. Our results show changes in acetylation and gene expression levels that are related to impaired neuronal development, and key regulators clearly defined in 6-week-old mice are proposed to drive the downstream regulatory cascade in HD. Here, we describe the first approach to determine the relationship among epigenetic changes in the early stages of HD. We determined the existence of changes in pre-symptomatic stages of HD as a starting point for early onset indicators of the progression of this disease.

Healthcare utilization and direct medical costs of Huntington’s disease among Medicaid beneficiaries in the United States

AimsTo provide more recent estimates of healthcare utilization and costs in Huntington’s disease (HD) in the Medicaid population.Materials and MethodsThis retrospective analysis used administrative claims data for HD beneficiaries (≥1 HD claim; ICD-9-CM 333.4) from Medicaid Analytic eXtract data files from 1 January 2010–31 December 2014. The date of the first HD claim during the identification period (1 January 2011–31 December 2013) was assigned as the index date. If a beneficiary had multiple HD claims during the identification period, one was randomly chosen as the index date. Beneficiaries were required to be continuously enrolled in fee-for-service plans during the 1-year pre-index and post-index periods. Medicaid beneficiaries without HD were drawn from a 100% random sample and matched (3:1) to those with HD. Beneficiaries were classified by disease stage (early/middle/late). All-cause and HD-related (any utilization related to HD diagnosis or symptoms associated with HD) healthcare utilization and costs were reported.ResultsA total of 1,785 beneficiaries without HD were matched to 595 beneficiaries with HD (139 early-, 78 middle-, and 378 late-stage). The mean (SD) annual total costs were higher for beneficiaries with HD than beneficiaries without HD ($73,087 [$75,140] vs. $26,834 [$47,659], p <.001) and driven by inpatient costs ($45,190 [$48,185] vs. $13,808 [$39,596], p <.001). Total healthcare costs were highest among beneficiaries with late-stage HD (mean [SD] cost: $22,797 [$31,683] for early-stage HD vs. $55,294 [$129,290] for middle-stage HD vs. $95,251 [$60,197] for late-stage HD; p <.001).LimitationsAdministrative claims are intended for billing purposes and subject to coding errors. This study did not address functional status, which may provide further insight to late-stage and end-of-life burden of HD, and indirect costs.ConclusionsMedicaid beneficiaries with HD have higher acute healthcare utilization and costs compared to beneficiaries without HD, which tend to increase with disease progression, indicating that HD beneficiaries at later disease stages have greater burden.

Wearable Activity Monitors to Support Physical Activity Interventions in Neurodegenerative Disease: A Feasibility Study

Aim: To evaluate the feasibility of using activity monitors in a physical activity (PA) intervention in people with Parkinson's (PD) and Huntington's disease (HD). Materials &amp; methods: People with early-stage PD (n = 13) and HD (n = 14) enrolled in a 4-month coaching program, wore a Fitbit, and were guided through a behavioral intervention to facilitate PA uptake. Wear time, wear habits and activity metrics (e.g., steps) were analyzed. Results: Retention rate was 85% and participants had an average 92.3% (±9.2) valid wear days. Daily wear time was 18.4 (±4.5) h. Day &amp; night Fitbit wearers showed improvements in steps (d = 1.02) and MET×min/week (d = 0.69) compared with day-only wearers. Conclusion: Implementing wearables in a coaching intervention was feasible and provided insights into PA behavior.

Implications of Tau Dysregulation in Huntington's Disease and Potential for New Therapeutics.

Huntington's disease (HD) is an autosomal dominant neurodegenerative disorder. The disease, characterized by motor, cognitive, and psychiatric impairments, is caused by the expansion of a CAG repeat in the huntingtin gene. Despite the discovery of the mutation in 1993, no disease-modifying treatments are yet available. Understanding the molecular and cellular mechanisms involved in HD is therefore crucial for the development of novel treatments. Emerging research has found that HD might be classified as a secondary tauopathy, with the presence of tau insoluble aggregates in late HD. Increased total tau protein levels have been observed in both HD patients and animal models of HD. Tau hyperphosphorylation, the main feature of tau pathology, has also been investigated and our own published results suggest that the protein phosphorylation machinery is dysregulated in the early stages of HD in R6/1 transgenic mice, primarily in the cortex and striatum. Protein phosphorylation, catalysed by kinases, regulates numerous cellular mechanisms and has been shown to be dysregulated in other neurodegenerative disorders, including Alzheimer's disease. While it is still unclear how the mutation in the huntingtin gene leads to tau dysregulation in HD, several hypotheses have been explored. Evidence suggests that the mutant huntingtin does not directly interact with tau, but instead interacts with tau kinases, phosphatases, and proteins involved in tau alternative splicing, which could result in tau dysregulation as observed in HD. Altogether, there is increasing evidence that tau is undergoing pathological changes in HD and may be a good therapeutic target.

Chorea Severity Change Over Time in Huntington Disease and by Huntington Disease Stage (P1-11.010)

<h3>Objective:</h3> To describe chorea severity over time in individuals with Huntington disease (HD) stratified by Total Functional Capacity (TFC). <h3>Background:</h3> Chorea, the most common motor symptom in HD, negatively affects quality of life and TFC. Addressing chorea is crucial to reduce the burden of motor symptomatology in HD. Chorea has been reported to increase initially, plateau, and potentially decrease over time; however, longitudinal data assessing chorea severity by disease stage are limited. <h3>Design/Methods:</h3> Participants were adults from Enroll-HD, a global, longitudinal, observational registry for individuals with or at risk for HD (data cut 2013–31 October 2020). The manifest population was stratified by baseline TFC score as a proxy for HD stage (TFC 7–13/stage 1–2 [early], 3–6/stage 3 [middle], 0–2/stage 4–5 [late]). Chorea severity was assessed by Total Maximal Chorea (TMC) score at baseline and at annual visits. Patients with ≥4 years of follow-up were selected for estimating chorea progression over time. <h3>Results:</h3> The manifest population was grouped by HD stage: early, n=7441; middle, n=2330; late, n=1120. Baseline TMC scores (mean [SD]) increased as HD stage progressed (early, 8.0 [4.7]; middle, 10.4 [5.8]; late, 10.6 [6.9]). For participants with ≥4 years of follow-up (n=1271), TMC scores increased over time in early-stage HD (n=963; years 1–2, 8.5 [5.0]; years 2–3, 9.1 [5.3]; years 3–4, 9.5 [5.6]), but plateaued at high levels in middle- (n=222; 10.6 [5.3]; 10.6 [6.0]; 10.1 [5.7], respectively) and late-stage HD (n=86; 10.4 [6.6]; 9.8 [6.9]; 9.7 [6.2]). <h3>Conclusions:</h3> Chorea severity increased in early-stage HD, and plateaued in middle- and late-stage HD. Chorea severity did not decrease longitudinally in any stage; however, the limited sample size for the follow-up period should be considered. These results support the need for increased awareness about the potential for persistent chorea in late-stage HD. <b>Disclosure:</b> Dr. Furr-Stimming has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Teva Pharmaceuticals. Dr. Furr-Stimming has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Michael J. Fox Foundation. Dr. Furr-Stimming has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Teva Pharmaceuticals. The institution of Dr. Furr-Stimming has received research support from Cures within Reach. The institution of Dr. Furr-Stimming has received research support from Huntington’s Disease Society of America. The institution of Dr. Furr-Stimming has received research support from Roche/Genetech. The institution of Dr. Furr-Stimming has received research support from Uniqure. The institution of Dr. Furr-Stimming has received research support from CHDI. The institution of Dr. Furr-Stimming has received research support from Huntington Study Group/Neurocrine. The institution of Dr. Furr-Stimming has received research support from NIH/University of Iowa. The institution of Dr. Furr-Stimming has received research support from Sage Therapeutics. Dr. Furr-Stimming has received publishing royalties from a publication relating to health care. Dr. Sung has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for Teva Neuroscience. Dr. Sung has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for Genentech. Dr. Reshef has received personal compensation for serving as an employee of Teva. Ms. Willock has received personal compensation for serving as an employee of HCD Economics. Rinat Ribalov has received personal compensation for serving as an employee of TEVA. Miss Brighton has nothing to disclose. Dr. Leo has received personal compensation for serving as an employee of Teva Pharmaceutical Industries.

Divergent cognitive trajectories in early stage Huntington's disease: A 3-year longitudinal study.

Cognitive impairment is a central feature of Huntington's disease (HD), but it is unclear to what extent more aggressive cognitive phenotypes exist in HD among individuals with the same genetic load and equivalence in other clinical and sociodemographic variables. We included Enroll-HD study participants in early and early-mid stages of HD at baseline and with three consecutive yearly follow-ups for whom several clinical and sociodemographic as well as cognitive measures were recorded. We excluded participants with low and large CAG repeat length (CAG < 39 & > 55), with juvenile or late onset HD, and with dementia at baseline. We explored the existence of different groups according to the profile of cognitive progression using a two-step k-means cluster analysis model based on the combination of different cognitive outcomes. We identified a slow cognitive progression group of 293 participants and an aggressive progression group (F-CogHD) of 235 for which there were no differences at the baseline visit in any of the measures explored, with the exception of a slightly higher motor score in the F-CogHD group. This group showed a more pronounced annual loss of functionality and a more marked motor and psychiatric deterioration. The rate of progression of cognitive deterioration in HD is strongly variable even between patients sharing, among other variables, equivalent CAG repeat length, age, and disease duration. We can recognize at least two phenotypes that differ in terms of rate of progression. Our findings open new avenues to study additional mechanisms contributing to HD heterogeneity.

Update of Rehabilitation in Huntington's Disease: Narrative Review.

Huntington's disease (HD) is a neurodegenerative disease that has motor dysfunction, predominantly chorea, cognitive impairment, and psychiatric disturbances as symptoms. Treatment is directed to reduce the severity of symptoms, although there are few studies and no clinical guidelines for rehabilitation in HD. Therefore, this review aimed to establish an effective rehabilitation approach for HD according to the stage of the disease. In the early stage of HD, the motor symptoms are mild, and psychological symptoms occur. Treatment in this period should focus on aerobic and resistance exercises, task-specific training, secondary prevention education, cognitive training, and psychological management. In the middle stage of HD, the motor symptoms are more severe. Task-specific rehabilitation approaches, education for the patient and caregiver, functional respiratory exercises, activities of daily living training, multidisciplinary and multimodal daycare rehabilitation are helpful to patients in this stage. At the late stage of HD, most patients need complete support for activity of daily living. Mobility and balance evaluation and prevention strategies should be focused on for safety, and respiratory exercises and physical exercise to prevent complications in patients with severely impaired mobility should be considered based on the patient's condition. Programmed rehabilitation management based on the stage of the disease is effective for patients with HD.

Early TNF-Dependent Regulation of Excitatory and Inhibitory Synapses on Striatal Direct Pathway Medium Spiny Neurons in the YAC128 Mouse Model of Huntington's Disease.

Huntington's disease (HD) is a neurodegenerative disease caused by a polyglutamine expansion in the huntingtin gene. Neurodegeneration first occurs in the striatum, accompanied by an elevation in inflammatory cytokines. Using the presymptomatic male YAC128 HD model mouse, we examined the synaptic input onto the striatal medium spiny neurons to look for early changes that precede degeneration. We observed an increase in excitatory synaptic strength, as measured by AMPA/NMDA ratios, specifically on direct pathway D1 receptor expressing medium spiny neurons, with no changes on indirect pathway neurons. The changes in excitation were accompanied by a decrease in inhibitory synaptic strength, as measured by the amplitude of miniature inhibitory synaptic currents. The pro-inflammatory cytokine tumor necrosis factor alpha (TNF) was elevated in the striatum of YAC128 at the ages examined. Critically, the changes in excitatory and inhibitory inputs are both dependent on TNF signaling, as blocking TNF signaling genetically or pharmacological normalized synaptic strength. The observed changes in synaptic function are similar to the changes seen in D1 medium spiny neurons treated with high levels of TNF, suggesting that saturating levels of TNF exist in the striatum even at early stages of HD. The increase in glutamatergic synaptic strength and decrease in inhibitory synaptic strength would increase direct pathway neuronal excitability, which may potentiate excitotoxicity during the progress of HD.SIGNIFICANCE STATEMENT The striatum is the first structure to degenerate in Huntington's disease, but the early changes that presage the degeneration are not well defined. Here we identify early synaptic changes in the YAC128 mouse model of Huntington's disease specifically on a subpopulation of striatal neurons. These neurons have stronger excitatory synapses and weaker inhibitory inputs, and thus would increase the susceptibility to excitotoxicity. These changes are dependent on signaling by the pro-inflammatory cytokine TNFα. TNF is elevated even at early presymptomatic stages, and blocking TNF signaling even acutely will reverse the synaptic changes. This suggests early intervention could be important therapeutically.

Economic burden of Huntington disease in Europe and the USA: Results from the Huntington's Disease Burden of Illness study.

The prevalence of Huntington disease (HD) has increased over time; however, there is a lack of up-to-date evidence documenting the economic burden of HD by disease stage. This study provides an estimate of the annual direct medical, nonmedical, and indirect costs associated with HD from participants in the Huntington's Disease Burden of Illness (HDBOI) study in five European countries and the USA. The HDBOI is a retrospective, cross-sectional study. Data collection was conducted between September 2020 and May 2021. Participants were recruited by their HD-treating physicians and categorized as early stage (ES), mid stage (MS), or advanced stage (AS) HD. Data were collected via three questionnaires: a case report form, completed by physicians who collected health care resource use associated with HD to compute direct medical cost, and optional patient and caregiver questionnaires, which included information used to compute nondirect medical and indirect costs. Country-specific unit cost sources were used. HDBOI cost estimates were €12,663 (n= 2094) for direct medical costs, €2984 (n= 359) for nondirect medical costs, and €47,576 (n= 436) for indirect costs. Costs are higher in patients who are at later stages of disease; for example, direct medical costs estimates were €9220 (n= 846), €11,885 (n= 701), and €18,985 (n= 547) for ES, MS, and AS, respectively. Similar trends were observed for nondirect and indirect costs. Costs show large variations between patients and countries. Cost estimates from the HDBOI study show that people with HD and their caregivers bear a large economic burden that increases as disease progresses.

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 A2A receptors (A2AR), 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 (A2AR agonist), caffeine (non-selective of A1R and A2AR antagonist), ZM 241385 (A2AR 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 A2AR antagonists have an essential role in modulating locomotor function, whereas the activation of A1R and blockade of A2AR and A1R and modulation of adenosine levels may reduce the memory impairment, which could be a potential pharmacological strategy against late-stage symptoms HD.

Hyperactive Striatal Dopamine Signaling Observed in Huntington’s Disease Mouse Models Prior to Motor Symptom Onset Can be Attenuated via Activation of M4 Receptors

Almost all Huntington’s Disease (HD) patients die within 10‐30 years after symptom onset and currently there are no available treatments to slow, stop, or reverse its progression. HD is a neurodegenerative disease that causes a biphasic signaling pattern in the striatum in which there is hyperactive signaling during the early stages, followed by hypoactive signaling later on. Among the many neurotransmitters shown to follow the biphasic signaling pattern found in HD, dopamine (DA) and its inputs from the mid‐brain to the striatum are thought to be critical for motor and action planning. However, there is currently a lack of studies that directly examine DA signaling in animal models before symptom onset, leaving room for investigation in a critical area of the disease. Here we use a combination of techniques to assess dopamine signaling and its regulation during pre‐symptomatic disease stages. We hypothesized that we would observe increased dopamine transients in YAC128 positive mice when compared to littermate controls at this time point, and that activation of the M4 receptor with the M4 selective positive allosteric modulator (PAM) VU’154 would normalize transient amplitude in YAC128 mice. Using fast scanning cyclic voltammetry (FSCV), we recorded dopamine signaling in pre‐symptomatic YAC128 mice via ex vivo preparations. We also used, fiber photometry to record dopamine signaling in vivo, in the same mouse strain. We found that indeed, DA transient amplitudes are increased in pre‐symptomatic YAC128 mice when compared to littermate controls in both ex vivo and in vivo settings. Additionally, we report that activation of the M4 receptor is able to normalize the enhanced DA signaling in HD mice. These findings are some of the first to directly show increased DA signaling in the basal ganglia in early stage HD rodent models and support previous evidence that M4 ­­­­­­­is potentially an exciting target for normalizing aberrant neurotransmission in HD.