Guidelines for clinical pharmacological practices in Huntington's disease

Neuroleptic malignant syndrome in Huntington disease

BACKGROUND AND PURPOSE

Despite the wide use of dopamine receptor blocking agents (DRBAs) in Huntington disease (HD), neuroleptic malignant syndrome (NMS) is rarely described in this population. The aim of this study was to assess NMS prevalence in a large cohort of HD patients and explore the main associated risk factors.

METHODS

In 2023, an HD patient was admitted to our neurology department due to NMS. Starting from the case description, we performed a narrative review of the literature of NMS cases in HD, reviewed data from the fifth dataset of the Enroll-HD (a longitudinal, observational, global study of families with HD) study (PDS5) selecting HD patients treated with DRBAs and/or tetrabenazine (TBZ) who presented at least one of the core symptoms of NMS (rigidity and hyperthermia), and collected data to investigate prevalence of NMS and identify risk factors.

RESULTS

In the Enroll-HD PDS5 dataset, we identified 5108 of 11,569 HD patients who were undergoing DRBA and/or TBZ treatment. Only one patient, a Caucasian man of 46 years, undergoing clozapine and valproate treatment, had a registered diagnosis of NMS.

CONCLUSIONS

NMS in HD patients is seldom described. This could be due to an underestimation of this condition. There are no available objective NMS diagnostic criteria at present, and the existence of atypical forms of NMS further complicates diagnosis. Advanced disease stage, rigid-akinetic phenotype, abrupt therapy changes, polytherapy, and dehydration are key risk factors, most of which are preventable through awareness and caution in managing medications in the HD population.

Symptomatic treatment options for Huntington's disease (guidelines of the German Neurological Society)

INTRODUCTION

Ameliorating symptoms and signs of Huntington's disease (HD) is essential to care but can be challenging and hard to achieve. The pharmacological treatment of motor signs (e.g. chorea) may favorably or unfavorably impact other facets of the disease phenotype (such as mood and cognition). Similarly, pharmacotherapy for behavioral issues may modify the motor phenotype. Sometimes synergistic effects can be achieved. In patients undergoing pragmatic polypharmacological therapy, emerging complaints may stem from the employed medications' side effects, a possibility that needs to be considered. It is recommended to clearly and precisely delineate the targeted signs and symptoms (e.g., chorea, myoclonus, bradykinesia, Parkinsonism, or dystonia). Evidence from randomized controlled trials (RCTs) is limited. Therefore, the guidelines prepared for the German Neurological Society (DGN) for German-speaking countries intentionally extend beyond evidence from RCTs and aim to synthesize evidence from RCTs and recommendations of experienced clinicians.

RECOMMENDATIONS

First-line treatment for chorea is critically discussed, and a preference in prescription practice for using tiapride instead of tetrabenazine is noted. In severe chorea, combining two antidopaminergic drugs with a postsynaptic (e.g., tiapride) and presynaptic mode of action (e.g., tetrabenazine) is discussed as a potentially helpful strategy. Sedative side effects of both classes of compounds can be used to improve sleep if the highest dosage of the day is given at night. Risperidone, in some cases, may ameliorate irritability but also chorea and sleep disorders. Olanzapine can be helpful in the treatment of weight loss and chorea, and quetiapine as a mood stabilizer with an antidepressant effect.

CONCLUSIONS

Since most HD patients simultaneously suffer from distinct motor signs and distinct psychiatric/behavioral symptoms, treatment should be individually adapted.

Assessing the state of care for Huntington disease in the United States: Results from a survey of practices treating Huntington disease patients

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This research study of 156 US healthcare practices is the first of its kind to include non-specialty neurologists and primary care physician practices, as well as academic practices surveyed about their treatment of Huntington disease patients.

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One-half of HD practices surveyed saw 2 or less patients per month, while about one quarter of practices saw 1 or more patients per week.

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HD care appears to be inconsistently applied across the US. Differences were noted in a practice’s ability to provide care navigators, genetic counselors, or psychologists/psychiatrists, or to conduct pre-visit screening of their patients, or routinely monitor weight.

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Practices seeing a higher volume of HD patients and ones led by movement disorder-trained neurologists, tended to be better equipped to provide a broader range of multi-disciplinary care.

Background

No study to date has thoroughly examined US Huntington disease (HD) care delivery in a variety of clinic settings by HD specialists and non-specialists.

Objective

To obtain a clearer understanding of current care structure and delivery of care through a survey of representative US physicians treating HD patients.

Methods

We designed and fielded a survey of 40 closed-ended evaluative items and one open-ended item to a sample of 339 US practices. Unique to this survey was the inclusion of non-specialists.

Results

Responses were received from 156 practices (overall response rate 46.02 %), with 52.6 % from academic sites, 35.3 % from private practices, and 12.2 % from the VA. More than half (63.5 %) of the practice leads were movement disorder trained or Directors of HDSA Centers of Excellence and 58.3 % had an HD or multidisciplinary care clinic. However, 48.7 % of the practices saw 1–25 HD patients, 28.2 % saw 26–100 HD patients, and 23.1 % served over 100 HD patients annually. Most practices (>69 %) reported having difficulty providing social work, genetic counseling, care coordination and psychologists/psychiatrists. Increased HD practice size was associated with higher rates of pre-visit screenings, care navigator/care coordinators, routine monitoring of weight, and provision of genetic counseling by genetic counselors.

Conclusions

Not surprisingly, we found that HD care was inconsistently applied across the US. Practices led by neurologists trained in movement disorders, and higher HD volume practices, tended to be better equipped to provide multi-disciplinary staffing and procedures as compared to those with fewer numbers of HD patients.

[The handling of psychotropics in diseases of central nervous system]

Psychiatric signs and symptoms occur frequently in individuals with central nervous system diseases. Inadequately treated, these comorbid conditions affect patient rehabilitation, compliance with treatment and quality of life. Their management poses a major challenge given the variable efficacy and safety profiles of available psychotropic drugs and increased risk of drug interaction. This review aims to summarize the existing literature on the prescription of psychotropic drugs for management of psychiatric disorders among persons with central nervous system's diseases.

Sample enrichment for clinical trials to show delay of onset in huntington disease

BACKGROUND

Disease-modifying clinical trials in persons without symptoms are often limited in methods to assess the impact associated with experimental therapeutics. This study suggests sample enrichment approaches to facilitate preventive trials to delay disease onset in individuals with the dominant gene for Huntington disease.

METHODS

Using published onset prediction indexes, we conducted the receiver operating curve analysis for diagnosis within a 3-year clinical trial time frame. We determined optimal cut points on the indexes for participant recruitment and then conducted sample size and power calculations to detect varying effect sizes for treatment efficacy in reducing 3-year rates of disease onset (or diagnosis).

RESULTS

Area under the curve for 3 onset prediction indexes all demonstrated excellent value in sample enrichment methodology, with the best-performing index being the multivariate risk score (MRS).

CONCLUSIONS

This study showed that conducting an intervention trial in premanifest and prodromal individuals with the gene expansion for Huntington disease is highly feasible using sample enrichment recruitment methods. Ongoing natural history studies are highly likely to indicate additional markers of disease prior to diagnosis. Statistical modeling of identified markers can facilitate participant enrichment to increase the likelihood of detecting a difference between treatment arms in a cost-effective and efficient manner. Such variations may expedite translation of emerging therapies to persons in an earlier phase of the disease.

TRIAL REGISTRATION

PREDICT-HD is registered with www.clinicaltrials.gov, number NCT00051324. © 2019 International Parkinson and Movement Disorder Society.