Journal of Huntington's Disease

Transgenic sheep are currently the only large animal model of Huntington’s disease expressing full-length mutant human huntingtin. These transgenic sheep provide an opportunity to test adeno associated virus (AAV) therapies directly targeting the huntingtin gene. A recent study demonstrated that self-complementary (sc) AAV with artificial miRNA against human huntingtin reduced mutant human huntingtin in caudate and putamen after a single injection near the internal capsule.

To identify an AAV serotype among AAVrh8, AAV9 and AAVrh10 with the highest neuronal uptake and distribution, with no obvious cell loss in the neostriatum of the sheep.

We tested AAVrh8, AAV9 and AAVrh10 by stereotactic direct unilateral injection into the neostriatum of sheep, near the internal capsule. Four weeks after administration, we examined the viral spread and neuronal uptake of each serotype of AAV containing GFP. We compared single stranded (ss) and scAAVs. Further, we measured the distribution of AAVrh8 and AAV9 to a variety of tissues outside the brain.

Sc AAV9 had the best combination of neuronal uptake and distribution throughout the neostriatum. scAAVrh10 demonstrated good spread, but was not taken up by neurons. scAAVrh8 demonstrated good spread, but had less neuronal uptake than AAV9. Six hours after convection-enhanced administration to the neostriatum, both AAVrh8 and AAV9 viral genomes were detected in blood, saliva, urine, feces and wool. By four weeks, viral genomes were detected in wool only. Administration of AAVrh8, AAV9 and AAVrh10 was not associated with loss of neostriatal, medium spiny neuron number as measured by DARPP32 immunohistochemistry.

Altogether, we found scAAV9 had the best neuronal uptake and spread, showed no loss of neurons at one-month post-injection, and was not measurable in body fluids one month after injection. This information will guide future clinical experiments requiring brain injection of AAV for therapeutics for gene or miRNA deliveries in sheep transgenic for the human huntingtin gene.

Biochemical analysis of mutant huntingtin (mHTT) aggregation species in HD mice is a common measure to track disease. A longitudinal and systematic study of how tissue processing affects detection of conformers has not yet been reported. Understanding the homeostatic flux of mHTT over time and under different processing conditions would aid in interpretation of pre-clinical assessments of disease interventions.

Provide a systematic evaluation of tissue lysis methods and molecular and biochemical assays in parallel with behavioral readouts in R6/2 mice to establish a baseline for HTT exon1 protein accumulation.

Established biochemical methods were used to process tissue from R6/2 mice of specific ages following behavior tasks. Aggregation states and accumulation of mHTT exon 1 protein were evaluated using multiple break and assay methods to determine potential conformational flux assay specificity in detection of mHTT species, and tissue specificity of conformers.

Detection of mHTT exon 1 protein species varied based on biochemical processing and analysis providing a baseline for subsequent studies in R6/2 mice. Insoluble, high molecular weight species of mHTT exon 1 protein increased and tracked with onset of behavioral impairments in R6/2 mice using multiple assay methods.

Conformational flux from soluble monomer to high molecular weight, insoluble species of mHTT exon 1 protein was generally consistent for multiple assay methods throughout R6/2 disease progression; however, the results support the use of multiple biochemical techniques to detect mHTT exon 1 protein species for preclinical assessments in HD mouse models expressing mHTT exon 1 protein.

Critical to discovering targeted therapies for Huntington disease (HD) are validated methods that more precisely predict when clinical outcomes occur for different patient profiles.

To more precisely predict the probability of when motor diagnosis (diagnostic confidence level 4) on the Unified Huntington’s Disease Rating Scale (UHDRS), cognitive impairment (two or more neuropsychological scores on the UHDRS were 1.5 standard deviations below normative means) and Stage II Total Functional Capacity (TFC) first occur by accounting for dependencies between these outcomes.

Adult premanifest participants with ≥36 CAG repeats were selected from multi-center, longitudinal, observational studies: Prospective Huntington At Risk Observational Study (PHAROS, n = 346), Neurobiological Predictors of Huntington Disease (PREDICT, n = 909); and Cooperative Huntington Observational Research Trial (COHORT, n = 430). Probabilities were estimated for each study, and pooled using the Joint Progression of Risk Assessment Tool (JPRAT) which accounts for dependencies between outcomes.

All studies had similar probabilities of when motor diagnosis, cognitive impairment, and Stage II TFC first occurred. Probability estimates from JPRAT were 43% less variable than from models that ignored dependencies between outcomes. The probability of experiencing motor-diagnosis, cognitive impairment, and Stage II TFC within 5 years was 10%, 18%, and 7%, respectively for 45-year-olds with 42 CAG repeats, and was 4%, 10% and 5%, respectively, for 40 year olds with 42 CAG repeats.

Improved predictions from JPRAT may benefit treatment studies of rare diseases and is an alternative to composite outcomes when the objective is interpreting individual outcomes within the same model.

Huntington disease (HD) is a neurodegenerative disorder characterized by motor impairments (including chorea), along with behavioral, psychiatric, and cognitive symptoms. Tetrabenazine was the first US Food and Drug Administration (FDA)-approved treatment for chorea related to HD.

To examine pharmacologic treatment patterns among patients using tetrabenazine, including reasons for treatment initiation, non-initiation, dose adjustments, and discontinuation, and to quantify the burden of chorea based on healthcare resource utilization.

In this retrospective patient chart review, neurologists were recruited from the Medefield (http://www.medefield.com) opt-in panel, and selected ≤5 medical charts based on the criteria provided and abstracted data on demographics, disease history, healthcare resource use, and treatment patterns.

138 neurologists participated and 512 HD patient charts were reviewed. Among these patients, 26.4% did not initiate tetrabenazine. Most HD patients (66.5%) received a tetrabenazine dose ≤50 mg. The most common reasons for stopping upward titration were optimal chorea control (55.5%), intolerability of higher doses (31.2%), and reaching the maximum recommended dosage despite suboptimal chorea control (11.4%). Chorea severity and non-persistence to tetrabenazine were associated with increased emergency room visits, hospitalizations, and days hospitalized.

Although tetrabenazine was the sole FDA-approved treatment for HD chorea until April 2017, more than one-quarter of respondents never initiated therapy. Tetrabenazine dosing was lower than predicted, and many patients experienced adverse symptoms of intolerability at high doses. New safer and more tolerable treatment options, such as deutetrabenazine, may improve treatment outcomes and reduce healthcare resource use.

In clinical practice, several strategies and pharmacological options are available to treat neuropsychiatric symptoms of Huntington disease (HD). However, there is currently insufficient data for evidence-based guidelines on the management of these common symptoms.

We aimed to develop expert-based recommendations regarding the management of agitation, anxiety, apathy, psychosis, and sleep disorders.

Guideline development was based on a modified Institute of Medicine guideline process that accounted for a lack of evidence base. An international committee of 11 multidisciplinary experts proposed a series of statements regarding the description and management of each symptom. Statement assessment and validation was performed using a web-based survey tool and 84 international HD experts (neurologists and psychiatrists) who assessed the statements and indicated their level of agreement.

High-level agreement (≥85% experts strongly agreed or agreed) was reached for 107 of the 110 statements that have been incorporated into the expert-based clinical recommendations presented herein.

Clinical statements to guide the routine management of agitation, anxiety, apathy, psychosis, and sleep disorders in HD have been developed. Although not specifically tested in the HD population, clinical experience has shown that most of the neuropsychiatric symptoms discussed, when considered in isolation are treatable using pharmacologic and non-pharmacologic strategies developed for use in other populations. However, the management of neuropsychiatric symptoms in HD can be complex because neuropsychiatric symptoms often co-exist and treatment decisions should be adapted to cover all symptoms while limiting polypharmacy.

Huntington’s disease (HD) presents with motor, cognitive, and behavioral symptoms that impair functional capacity and the ability to maintain employment. The relative contribution of cognitive decline to work disability remains controversial.

To evaluate the association of cognitive decline, compared with motor decline, with the decision to leave work.

Data from the Enroll-HD observational study were analyzed. The correlation of age of cognitive symptom onset and age of motor symptom onset with age at leaving work was assessed. The association of the Stroop Color Naming Test (SCNT) cognitive assessment and the Total Motor Score (TMS) assessment (reverse scored) with the Total Functional Capacity (TFC) assessment was also assessed.

For every year delay in cognitive symptom onset, there was a 0.806 year increase in age at leaving work (SE = 0.030, p < 0.001, adj-R² = 0.628). For every year delay of motor symptom onset, there was a 0.814 year increase in age at leaving work (SE = 0.031, p < 0.001, adj-R² = 0.603). For every additional correct SCNT response given and for every unit increase in TMS, there was a 0.105 unit increase (SE = 0.006, p < 0.001, adj-R² = 0.315) and a 0.104 unit decrease in TFC (SE = 0.003, p < 0.001, adj-R² = 0.640), respectively.

Cognitive symptoms have a significant association, comparable to that of motor symptoms, with occupational functioning and the decision to leave work, suggesting that development of therapies for both cognitive and motor decline would be important for allowing people with HD to remain in the workforce longer.

Studies of physical therapy and multidisciplinary rehabilitation programs for Huntington’s disease (HD) have shown improvements in gait function, balance, and physical quality of life. There is a gap in the literature on effects of cognitive interventions and the potential to improve cognitive performance.

To assess changes in cognitive performance among patients with early to middle stage HD as secondary analyses from a one-year multidisciplinary rehabilitation program. The program included cognitive stimulation as a non-specific cognitive intervention in addition to physical interventions.

A one-year rehabilitation program that included comprehensive neuropsychological assessments was completed by 31 out 37 participants with early to middle stages of HD. Socio-demographic and clinical information was recorded. A battery of neuropsychological tests was used to measure cognitive functions before and after the intervention. Descriptive statistics was used for sample characteristics. Paired sample t-tests and nonparametric Wilcoxon Signed ranked tests were used to compare cognitive measures at both time points.

Scores on the Symbol Digit Modalities Test (SDMT) were significantly lower post intervention. There were no significant differences in all other measures. Scores on the Stroop color naming and California Verbal Learning Test-II (CVLT-II) long-term delayed recall tasks showed tendencies towards lower scores post intervention.

An intensive multidisciplinary rehabilitation program for patients with HD was generally well tolerated and feasible, with no indication of negative effects on cognition. Neuropsychological measures overall remained stable following an intensive multidisciplinary rehabilitation program, however continued progression of cognitive impairment was evident on the SDMT, suggesting that disease progression is not halted. Randomized controlled trials are needed to verify these findings.

For young people in families with Huntington’s disease (HD) the challenge of having an affected family member (AFM) compounds challenges related to being at risk of HD themselves.

This study aimed to quantitatively examine the experiences of young people in families with HD, adding to existing qualitative studies regarding teenagers and young adults in families with HD.

The experiences of young people with living in a family with HD were captured by an online anonymous questionnaire, available worldwide through the Huntington’s Disease Youth Organization. The questionnaire contained mostly forced choice questions.

Most participants (n = 84/101, 83.2%) provide assistance to an AFM and 46.4% (n = 39/84) wish they didn’t have to look after their AFM. Many participants (n = 64/78, 82.1%) reported feeling anxious about being at risk; 64.9% (n = 50/77) agreed it is a barrier in their life. Over one third (n = 29/76, 38.2%) of participants disagreed that they have support in relation to being at risk, despite 85.5% (n = 65/76) agreeing it is important to have support and ongoing follow up.

Young people in families with HD endure considerable emotional, social and practical burden secondary to having an AFM and being at risk themselves. Without increased support and services, the effects of being a young caregiver and living at risk are likely to have long term impacts on the well-being of these young people.