Current Pharmacological Management in Juvenile Huntington's Disease

Clinical Review of Juvenile Huntington's Disease

 Juvenile Huntington's disease (JHD) is rare. In the first decade of life speech difficulties, rigidity, and dystonia are common clinical motor symptoms, whereas onset in the second decade motor symptoms may sometimes resemble adult-onset Huntington's disease (AOHD). Cognitive decline is mostly detected by declining school performances. Behavioral symptoms in general do not differ from AOHD but may be confused with autism spectrum disorder or attention deficit hyperactivity disorder and lead to misdiagnosis and/or diagnostic delay. JHD specific features are epilepsy, ataxia, spasticity, pain, itching, and possibly liver steatosis. Disease progression of JHD is faster compared to AOHD and the disease duration is shorter, particularly in case of higher CAG repeat lengths. The diagnosis is based on clinical judgement in combination with a positive family history and/or DNA analysis after careful consideration. Repeat length in JHD is usually > 55 and caused by anticipation, usually via paternal transmission. There are no pharmacological and multidisciplinary guidelines for JHD treatment. Future perspectives for earlier diagnosis are better diagnostic markers such as qualitative MRI and neurofilament light in serum.

Pain in Huntington's disease and its potential mechanisms

Pain is common and frequent in many neurodegenerative diseases, although it has not received much attention. In Huntington's disease (HD), pain is often ignored and under-researched because attention is more focused on motor and cognitive decline than psychiatric symptoms. In HD progression, pain symptoms are complex and involved in multiple etiologies, particularly mental issues such as apathy, anxiety and irritability. Because of psychiatric issues, HD patients rarely complain of pain, although their bodies show severe pain symptoms, ultimately resulting in insufficient awareness and lack of research. In HD, few studies have focused on pain and pain-related features. A detailed and systemic pain history is crucial to assess and explore pain pathophysiology in HD. This review provides an overview concentrating on pain-related factors in HD, including neuropathology, frequency, features, affecting factors and mechanisms. More attention and studies are still needed in this interesting field in the future.

Juvenile Huntington's Disease: Diagnostic and Treatment Considerations for the Psychiatrist

Juvenile Huntington's disease (JHD) is a neurodegenerative disease with onset prior to the age of 21. While it accounts for a relatively small proportion of Huntington's disease (HD) diagnoses, its impact is significant on the quality of life for those affected. Clinicians may be unaware that HD can present in childhood and adolescence, delaying diagnosis. HD develops due to an expanded CAG repeat in the huntington gene. Rigidity, dystonia, and seizures are more common in JHD. Cognitive changes such as executive function impairments and decline in school performance are common. The burden of psychiatric symptoms is considerable and includes depression, anxiety, impulsivity, and aggression. While novel approaches to treatment interventions are investigated, current care is limited to targeting symptoms rather than disease modification. Prompt diagnosis and symptomatic treatment can maximize quality of life for these patients.

Quality of Life of Cypriot Patients Suffering with Huntington's Disease

Introduction: Huntington’s disease (HD) has profound motor, behavioural and cognitive symptoms. Despite the enormous burden of this disease on the quality of life (QoL) of patients and their families, there is very limited evidence on this topic. Considering the severity of HD patients, and the high prevalence in Cyprus more studies are needed to assess QoL among Cypriot patients, in order to improve our knowledge about their living conditions and to assist the management of this condition.

Project Aim: The aim of this cross-sectional study is to assess QoL among Cypriot patients with HD, using a standardized health-related QoL questionnaire.

Materials and Methods: A generic QoL questionnaire was used, namely EQ-5D, which is a standardised instrument for use as a measure of health outcomes and is applicable to a wide range of health conditions. The study was conducted with 34 patients, which represented 46% of the Cypriot HD patient population.

Results: Ability of patients to care for themselves and to carry out usual activities were reported to be most severely affected (37.5% and 40.6% replying “Severe Problems” respectively). Mobility and psychosocial well-being were also affected to a lesser extent (25.0% and 15.6% replying “Severe Problems”). Interestingly, in the anxiety/depression scale, 77.8% of asymptomatic patients reported “Some Problems”. Half of the patients did not experience pain or discomfort but 40.6% reported “Some Problems” and 6.3% reported “Severe Problems”. The Health Status as perceived by the patients was found to be moderately to severely affected.  In multivariate ordinal regression analyses, age at onset and disease duration significantly impacted on self-care. In addition, disease duration was significantly associated with mobility, self-care and usual activities scales. No significant determinants were evidenced for Pain/Discomfort and Anxiety/Depression. Lastly, age of onset was found to be the only significant determinant of the cumulative QoL score (Range=5-15).

Conclusions: Age at onset and disease duration were found to severely affect the QoL of Cypriot HD patients, and more specifically their mobility, ability to self-care and perform usual activities. The percentage of patients reporting “Some Problems” in the Pain/Discomfort category can be explained by the direct translation of the word as presented in the questionnaire, indicating the need for language specific instruments. Perhaps more noteworthy is the phychosocial burden on even asymptomatic patients, which needs to be acknowledged and managed to improve their quality of life.

Clinical trial perspective for adult and juvenile Huntington's disease using genetically-engineered mesenchymal stem cells

Progress to date from our group and others indicate that using genetically-engineered mesenchymal stem cells (MSC) to secrete brain-derived neurotrophic factor (BDNF) supports our plan to submit an Investigational New Drug application to the Food and Drug Administration for the future planned Phase 1 safety and tolerability trial of MSC/BDNF in patients with Huntington's disease (HD). There are also potential applications of this approach beyond HD. Our biological delivery system for BDNF sets the precedent for adult stem cell therapy in the brain and could potentially be modified for other neurodegenerative disorders such as amyotrophic lateral sclerosis (ALS), spinocerebellar ataxia (SCA), Alzheimer's disease, and some forms of Parkinson's disease. The MSC/BDNF product could also be considered for studies of regeneration in traumatic brain injury, spinal cord and peripheral nerve injury. This work also provides a platform for our future gene editing studies, since we will again use MSCs to deliver the needed molecules into the central nervous system.

Pridopidine for the treatment of Huntington's disease

INTRODUCTION

Huntington's disease is a rare dominantly-inherited neurodegenerative disease with motor, cognitive and behavioral manifestations. It results from an expanded unstable trinucleotide repeat in the coding region of the huntingtin gene. Treatment is symptomatic, but a poor evidence baseguides selection of therapeutic agents. Non-choreic derangements in voluntary movement contribute to overall motor disability and are poorly addressed by current therapies. Pridopidine is a novel agent in the dopidine class believed to have 'state dependent' effects at dopamine receptors, thus show promise in the treatment of these disorders of voluntary movement.

AREAS COVERED

This review discusses the pharmacokinetics and pharmacodynamics of pridopidine and reviews clinical trials supporting development of the drug for HD. This information was culled from literature searches for dopidines, pridopidine, and HD experimental therapeutics in PubMed and at http://www.clinicaltrials.org .

EXPERT OPINION

There is a compelling need to discover new treatments for motor disability in HD, particularly for non-choreic motor symptoms. While pridopidine failed to achieve its primary efficacy outcomes in 2 large trials, reproducible effects on secondary motor outcomes have fueled an ongoing trial studying higher doses and more focused clinical endpoints. This and phase III trials will define define the utility of pridopidine for HD.

Clinical diagnosis and management in early Huntington's disease: a review

This review focuses on clinical diagnosis and both pharmacological and nonpharmacological therapeutic options in early stages of the autosomal dominant inherited neurodegenerative Huntington's disease (HD). The available literature has been reviewed for motor, cognitive, and psychiatric alterations, which are the three major symptom domains of this devastating progressive disease. From a clinical point of view, one has to be aware that the HD phenotype can vary highly across individuals and during the course of the disease. Also, symptoms in juvenile HD can differ substantially from those with adult-onset of HD. Although there is no cure of HD and management is limited, motor and psychiatric symptoms often respond to pharmacotherapy, and nonpharmacological approaches as well as supportive care are essential. International treatment recommendations based on study results, critical statements, and expert opinions have been included. This review is restricted to symptomatic and supportive approaches since all attempts to establish a cure for the disease or modifying therapies have failed so far.

Managing juvenile Huntington's disease

Huntington's disease (HD) is a well-recognized progressive neurodegenerative disorder that follows an autosomal dominant pattern of inheritance. Onset is insidious and can occur at almost any age, but most commonly the diagnosis is made between the ages of 35 and 55 years. Onset ≤20 years of age is classified as juvenile HD (JHD). This age-based definition is arbitrary but remains convenient. There is overlap between the clinical pathological and genetic features seen in JHD and more traditional adult-onset HD. Nonetheless, the frequent predominance of bradykinesia and dystonia early in the course of the illness, more frequent occurrence of epilepsy and myoclonus, more widespread pathology, and larger genetic lesion means that the distinction is still relevant. In addition, the relative rarity of JHD means that the clinician managing the patient is often doing so for the first time. Management is, at best, symptomatic and supportive with few or no evidence-based guidelines. In this article, the authors will review what is known of the condition and present some suggestions based on their experience.