Huntington Disease (HD)


Huntington disease (HD) is a hereditary neurodegenerative disorder of the central nervous system caused by an expansion of cytosine-adenine-guanine (CAG) trinucleotide repeats in the huntingtin (HTT) gene. Cell degeneration in the brain associated with this mutation results in a combination of motor, cognitive, and psychiatric symptoms, including chorea (involuntary movements), muscle rigidity, cognitive decline, agitation, anxiety, apathy, and psychosis. Death occurs approximately 20 years following the onset of symptoms.1-3

Guidelines for Managing Neuropsychiatric Symptoms

In 2018, a set of consensus guidelines for the neuropsychiatric management of HD were published. This group developed expert-based definitions, clinical features, and treatment recommendations for neuropsychiatric symptoms of HD.1

Recommendations for Agitation

The treatment of coexisting psychiatric symptoms, medical comorbidities, and physical discomfort/pain may help to prevent agitation. Behavioral strategies and supportive environments can be implemented to promote calmness. The use of medications, such as benzodiazepines, antipsychotic drugs, and mood-stabilizing anti-epileptic drugs, can be considered as needed.1

Recommendations for Anxiety 

Cognitive behavioral therapies are advised, along with pharmacological options when necessary. These include selective serotonin reuptake inhibitors (SSRIs), benzodiazepines, and Remeron® (mirtazapine) for sleep disorders.1

Recommendations for Apathy 

Physical activity and social engagement are recommended, with potential use of pharmacological interventions that include antidepressant drugs.1

Recommendations for Psychosis

The treatment of medical comorbidities that can cause psychotic symptoms is recommended. Pharmacological treatment relies on antipsychotic drugs. Experts recommend a second-generation antipsychotic for first-line treatment and a first-generation alternative if the patient has dominant chorea. Clozaril® (clozapine) can be considered when the response to antipsychotics is refractory. Careful monitoring for adverse events that may indicate disease progression is required.1

Recommendations for Sleep Disorders 

Sleep hygiene is recommended. Suggested medications include melatonin, sedating antidepressants such as Remeron and Desyrel® (trazodone), and sedating neuroleptics such as Zyprexa® (olanzapine) and Seroquel® (quetiapine).1

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International Guidelines for HD Treatment 

In 2015, the European Huntington’s Disease Network (EHDN) commissioned a consensus group of experts to review the literature and provide evidence-based recommendations for HD management. Their goal was the standardization of pharmacological, nonpharmacological, and surgical treatment recommendations for the improvement of patient care and quality of life. These guidelines were published in 2019.2

Recommendations for Motor Disorders

Treatment recommendations are given for addressing the various motor disorders of HD, such as chorea, dystonia, rigidity, myoclonus, swallowing dysfunction, gait and balance dysfunction, and dexterity.2 These recommendations include pharmacological therapies and treatment with physical, occupational, and speech therapy. Xenazine® (tetrabenazine) and Austedo® (deutetrabenazine) are first-line treatments for chorea in patients without depression or suicidal ideation. Physiotherapy and/or personalized exercise programs are recommended for most symptoms of motor dysfunction, as active and passive physical therapy can help improve or maintain mobility. Rehabilitation specialists can recommend protective measures, assistive technology devices, and positioning techniques. Some motor disorders can be both a symptom or a side effect of pharmacological treatment. Careful evaluation is required to determine if dosage reductions or withdrawal of therapies are required.

Recommendations for Cognitive Disorders

Recommendations are given for addressing the various cognitive disorders, such as social cognition, executive function, memory decline, language/communication dysfunction, and disorientation.2 Cognitive disorders often manifest before motor symptoms, and rehabilitation therapies, such as speech therapy, occupational therapy, and psychomotricity, should be initiated.2

Recommendations for Psychiatric Disorders

Recommendations are also given for addressing the symptoms associated with various psychiatric disorders, such as suicidal ideation, depression, anxiety, impulsivity, obsessive thoughts, and hallucinations. The management of psychiatric disorders should be based on the identified triggers of mood changes. Recommendations include psychotherapy and cognitive behavioral therapy, along with pharmacological therapies. Treatment with antidepressants such as SSRIs or serotonin noradrenaline reuptake inhibitors (SNRIs) may be used, as well as anxiolytics and neuroleptics. Depression, social isolation, and impulsivity should be addressed to prevent suicidal behavior.2

Recommendations for Complications

Finally, recommendations are given for the treatments of other associated complications, such as weight loss, sleep disorders, dysphagia, urinary incontinence, and hypersalivation.2

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Physical Therapy Recommendations 

Recent guidelines developed by the Huntington Study Group (HSG) and the EHDN provide evidence-based recommendations for the effective use of physical therapy in patients with HD. The recommendations are designed to address the unique motor and functional challenges these patients face, with the aim of optimizing their physical well-being and overall quality of life.4

The guidelines emphasize the importance of a comprehensive initial assessment of motor function, balance, gait, muscle strength, and functional abilities. Assessment tools and standardized tests can be used to track changes in physical abilities over time.

Individualized exercise programs are recommended to address motor impairments. Programs should focus on improving flexibility, muscle strength, endurance, and coordination.4

Strategies for gait training and balance exercises to enhance mobility and reduce the risk of falls are provided. Assistive devices and adaptive techniques may be integrated to improve walking and postural stability. Regular range-of-motion exercises and stretching routines to maintain joint mobility and prevent contractures are also included.4

Practical exercises targeting the activities of daily living are highlighted, with the aim of improving independence and quality of life, as are breathing exercises and techniques to improve respiratory muscle strength.4

Strategies to assess the patient’s risk for falls and implement interventions to prevent them, such as improving balance and modifying the environment, are provided. Physical therapists are advised to address pain and discomfort through appropriate techniques that can address the motor and sensory symptoms of HD.4

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References

  1. Anderson KE, van Duijn E, Craufurd D, et al. Clinical management of neuropsychiatric symptoms of Huntington disease: expert-based consensus guidelines on agitation, anxiety, apathy, psychosis and sleep disorders. J Huntingtons Dis. 2018;7(3):355-366. doi:10.3233/JHD-180293
  2. Bachoud-Lévi AC, Ferreira J, Massart R, et al. International guidelines for the treatment of Huntington’s disease. Front Neurol. 2019;10:710. doi:10.3389/fneur.2019.00710
  3. Ajitkumar A, De Jesus O. Huntington disease. StatPearls [Internet]. Updated February 12, 2023. Accessed August 11, 2023.
  4. Quinn L, Kegelmeyer D, Kloos A, Rao AK, Busse M, Fritz NE. Clinical recommendations to guide physical therapy practice for Huntington disease. Neurology. 2020;94(5):217-228. doi:10.1212/WNL.0000000000008887

Reviewed by Harshi Dhingra, MD, on 8/14/2023.

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