Huntington’s Disease (HD)

Huntington’s disease (HD) is a progressive brain disorder that is inherited and caused by a single defective gene on chromosome 4. The defect is dominant and anyone who inherits it from a parent will develop the disease.¹  Every child of a parent with HD has a 50/50 chance of inheriting the faulty gene.²  The disorder is named for the physician who first describe it in the 1800s. The defective gene codes for the protein called huntingtin. This protein’s function is not yet known, but is called huntingtin because scientists identified its defective form as the cause of HD.¹  There is currently no cure for HD.

Epidemiology

• About 5-7 per 10,000 are affected in populations of white people.³ 
• Rates are much lower in most of Asia.⁴ 
• African populations show a similarly reduced prevalence.⁵ 

Pathology

Neuropathological changes from HD are selective and result in prominent cell loss and atrophy in the caudate and putamen.^6 7 8  Chorea is likely to be associated with the course of HD because of involvement of basal ganglia-thalamocoritcal circuitry.⁹  The substantial, cortical layers, hippocampus, and parietal lobe may be affected.^10 11 12 

Stages and Phases

• Prenatal testing
• Presymptomatic testing/Prediagnosis
• Diagnosis
• Stage I – Disability
• Stage II – Managing Behavior
• Stage II – Dependence
• Stave IV – End of Life¹³ 

Diagnosis and Symptoms

The brain may be free of neurodegeneration in early symptomatic stages. Eventually, there will be evidence of neurodegeneration and neuronal dysfunction, even in asymptomatic individuals. Neuronal dysfunction includes synaptic function, cytoskeletal integrity, and axonal transport.^14 15 16  MRI and CT may be unhelpful in early HD but in moderate to severe HD, they may show loss of striatal volume and increased size of frontal horns in the lateral ventricles.¹⁷  In the prediagnostic phase, individuals may become irritable, disinhibited, and unreliable at work. They may have difficulty with multitasking, be forgetful, and have increasing anxiety. Family members may notice restlessness or fidgeting. The patient then moves onto the diagnostic phase and is affected by chorea, incoordination, motor impersistence, and slowed saccadic eye movements.

Individuals may be symptomatic at any time, e.g., ages 1-80 years. In the presymptomatic stage, they may be healthy and have no detectable clinical abnormalities.¹⁸  Most people develop symptoms during adulthood between ages 30 to 50 – during the prime working years. HD can also occur in children and young adults and is known as juvenile HD or JHD.

In general, symptoms of HD can vary from person to person. Symptoms usually worsen over the course of the disease:

• Physical
• Mental
• Emotional
• Personality/Behavioral

More specifically:

• Personality changes
• Mood swings
• Depression
• Forgetfulness
• Impaired judgment
• Unsteady gait – e.g., “drunken” walk, bumping into objects, trouble recovering balance, falls risk
• Involuntary movements (chorea) – fingers, feet, face, torso; jerking or twitching movements of low or high amplitude. Examples include finger flicking, shoulder shrugging, face grimacing, or limb flailing. Contributes to difficulty with speaking, chewing, swallowing, reading.
• Slurred speech
• Dysphagia
• Weight loss (due to chorea) ² 
• Irritability
• Anger
• Fatigue
• Suicide ideation
• Social avoidance
• Poor attention
• Decision making
• Prioritizing tasks
• Learning and remembering
• Rigidity
• Akinesia (no or delayed initiation of movement that may last several seconds)
• Dystonia – abnormal sustained posturing, e.g., arching of the back, twisting of the neck to one side, may cause stiffness or rigidity
• Insomnia
• Seizures¹⁹ 
• Obsessive-compulsive thoughts and actions¹ 
• Akathisia – motor restlessness, difficulty maintaining a position or a need for constant movement, being “supercharged” all the time.
• Bradykinesia – slowed execution of movements
• Incoordination – alternation of rhythmical repetitive movements; affects walking, chewing, and breathing.
• Loss of fine motor control
• Impaired modulation of force for activities²⁰ 

Frequent Symptoms (20-50%)

• Disinhibition
• Depressed mood
• Euphoria
• Aggression

Infrequent Symptoms (5-12%)

• Delusions
• Compulsions

Rare Symptoms (less than 5%)

• Hypersexuality
• Hallucinations

Behavioral Symptoms

• Apathy
• Lack of initiative
• Dysphoria
• Irritability
• Agitation
• Anxiety
• Poor self-care
• Poor judgment
• Inflexibility^21 22 

Treatment

Treatment aims to slow or reverse the progression of HD. Many interventions help to manage HD symptoms. Occupational therapists can work with patients and families to develop strength, move safely, and adjust the home environment and activities.² 

• Neurotransmitter modulation for symptoms
• Tetrabenazine, Deutetrabenazine – causes the depletion of dopamine for treating involuntary movements
• Risperidone, olanzapine, haloperidol, clonazepam (Antipsychotics) – helps to lessen chorea and may control hallucinations, delusions, and violent outbursts
  • Does not help with involuntary muscle contractions, may worsen the condition and cause stiffness and rigidity.
• Citalopram (Celexa – SSRI), fluoxetine (Proxac – SSRI), sertraline (Zoloft – SSRI), nortriptyline (Pamelor, Tricyclic) – for depression
• Tranquilizers – for anxiety
• Lithium – for pathological excitement and severe mood swings¹⁹ 

Outcome Measures

• Barthel Index
• AMPS

Occupational Therapy

OT plays a key role in maximizing function and quality of life for those with HD. OT can help those with HD to engage in meaningful occupations and improve their overall occupational functioning, quality of life, and reduce challenging behaviors.²³ 

General Recommendations

• Introduce simpler meals that are more convenient; online shopping.
• Using a trolley may help with the transport of objects.
• A microwave may be a better alternative than a conventional cooker.
• Reorganize items to help make finding items easier.
• Ensure that smoke alarms are placed and working properly.
• Recommend assist when necessary with occupations.
• Refer to services that can provide such support.
• Refer to support groups and associations for HD.

Early Stage HD

• Explain the benefits of occupational therapy.
• Educate client and family about the disease process, symptoms, outcomes.
• Coordinate with family and caregivers.
• Improve oral motor control to prevent weight loss.
• Improve safety and mobility.
• Promote strategies for communication and learning.
• Maintain the highest possible quality of life.
• Address cognitive disability.
• Establish a daily routine that is consistent.
• Modify the environment, e.g., label items
• Communicate effectively: short sentences, ask to repeat important points back, reduce unnecessary stimuli.
• Use compensatory techniques, e.g., lists, calendars, notes.
• Divide complex tasks into simple tasks.
• Perform a home assessment for important occupations.
• Make recommendations for safety and participation, e.g., storage height of items, kitchen timers, lowering hot temperatures, using oven mitts, using non-skit mats, using shower chairs or benches, using grab bars, stabilizing furniture, using chairs with armrests, clearing unnecessary clutter, remove throw rugs, pad furniture.
• Prevent contractures: splinting, especially at night time.
• Address psychosocial: suicide ideation, anxiety, depression, isolation.

Mid-stage HD

• Address cognitive deficits and motor control difficulties.
• Address the loss of ability to perform tasks (physically, cognitively, emotionally).
• Offer suggestions to overcome difficulty with initiation.
• Incorporate rest breaks for fatigue.
• Improve posture and position for meals.
• Wrap legs around chair legs to stabilize the pelvis, place elbows on the table to stabilize the upper torso.
• Use built-up handles and take breaks as necessary for eating.
• Use non-skin placemats or Dycem for meals.
• Use covered cups, mugs, or water bottles to prevent spills.
• Customize the routine to the individual to prevent loss of interest in personal hygiene.
• Use shower mitts or ‘soap on a rope’.
• Use electric razors or chemical hair removers.
• Build up handles for grooming.
• Place outfits together and label them to reduce decision-making.
• Use clothes with less fasteners and minimize the use of fine motor skills.
• Dress while sitting on a stabilized chair to minimize falls and fatigue.

Later Stage HD

• Prevent falls and injuries
• Provide caregiver assistance and education for routines.
• Modify and adapt activities based on symptoms.²⁰ 

Additional Reading

OT Clinical Tips by the Huntington’s Disease Association and European Huntington’s Disease Network:

• Self Care (ADLs)
• Eating and Drinking
• IADLs
• Seating and Posture
• Sleep
• Social and Leisure
• Community
• Work

Bookmark

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