Huntington’s Disease

Huntington’s disease has a broad impact on a person’s functional abilities and usually causes movement, thinking (cognitive) and psychiatric disorders. Symptoms vary greatly and can change throughout the course of the disease.

Movement disorders associated with Huntington’s disease can include:

• Involuntary jerking or writhing movements (chorea)
• Muscle problems, such as rigidity or muscle contracture (dystonia)
• Slow or abnormal eye movements
• Impaired walking, posture and balance
• Difficulty with speech or swallowing

Impairments in voluntary movements, rather than the involuntary movements, may have a greater impact on a person’s ability to work, perform daily activities, communicate and remain independent.

Cognitive impairments often associated with Huntington’s disease include:

• Difficulty organizing, prioritizing or focusing on tasks
• Lack of flexibility or the tendency to get stuck on a thought, behaviour or action 
• Lack of impulse control that can result in outbursts, acting without thinking 
• Lack of awareness of one’s own behaviours and abilities
• Slowness in processing thoughts or ”finding” words
• Difficulties in learning new information

Depressive illness is the most common psychiatric disorder associated with Huntington’s disease. Depression appears to occur due to injury to the brain which causes changes in brain function. Signs and symptoms may include:

• Feelings of irritability, sadness or apathy
• Social withdrawal
• Insomnia
• Fatigue and loss of energy
• Frequent thoughts of death, dying or suicide

Other common psychiatric disorders include:

• Obsessive-compulsive disorder – by recurrent, intrusive thoughts and repetitive behaviours
• Mania – which can cause elevated mood, overactivity, impulsive behaviour and inflated self-esteem
• Bipolar disorder – alternating episodes of depression and mania

Weight loss is also common in people with Huntington’s disease, especially as the disease progresses.

Huntington’s disease may present differently and progress faster in younger people that in adults. 

Problems that often present early in the course of the disease include:

• Behavioural problems and attention difficulties which may affect school performance
• Physical changes such as contracted and rigid muscles, tremors or slight involuntary movements, seizures, falls or clumsiness

The symptoms of Huntington’s disease can be caused by several different conditions and therefore it is important to see your doctor so that a thorough investigation can be carried out.

After Huntington’s disease starts, a person’s functional abilities gradually worsen over time. The rate of disease progression and duration varies. The time from disease emergence to death is often about 10 to 30 years. Juvenile Huntington’s disease usually results in death within 10 years after symptoms develop.

The clinical depression associated with Huntington’s disease may increase the risk of suicide. Some research suggests that the greater risk of suicide occurs before a diagnosis is made and in the middle stages of the disease when a person starts to lose independence.

Eventually, a person with Huntington’s disease requires help with all activities of daily living and care. Late in the disease, he or she will likely be confined to a bed and unable to speak. Someone with Huntington’s disease is generally able to understand language and has an awareness of family and friends, though some will not recognize family members.

Common causes of death include:

• Pneumonia or other infections
• Injuries related to falls
• Complications related to the inability to swallow

Huntington’s disease is an autosomal dominant genetic disorder which means that a person needs only one copy of the defective gene which causes Huntington’s disease to develop the disorder.

An initial medical and family history and general physical examination will be carried out.

A neurological examination may be needed to test: 

• Motor symptoms – such as reflexes, muscle strength and balance
• Sensory symptoms – including sense of touch, vision and hearing
• Psychiatric symptoms – such as mood and mental status

Neuropsychological testing may be performed to test memory, reasoning, mental agility and language skills.

A psychiatric evaluation may also be required.

Brain-imaging tests, such as MRI or CT scans, may be ordered to assess the structure or function of the brain. 

Genetic testing can confirm the diagnosis.

Predictive genetic testing may be provided for those who have a family history of the disease but do not have symptoms.

Genetic counselling must be provided before taking a test and can also provide information about the inheritance patterns of Huntington’s disease.

There is no treatment to prevent or reverse the physical and mental decline associated with the condition, but medications may help to manage the symptoms of Huntington’s disease. 

Medications need to be regularly reviewed according to symptoms and side effects. 

Drugs to treat movement disorders include the following:

• Tetrabenazine (Xenazine) and deutetrabenazine (Austedo) may help suppress the involuntary jerking and writhing movements (chorea) associated with Huntington’s disease. Possible side effects include drowsiness, restlessness, and the risk of worsening or triggering depression or other psychiatric conditions.
• Antipsychotic drugs, such as haloperidol (Haldol) and fluphenazine, have a side effect of suppressing movements. However, these drugs may worsen involuntary contractions (dystonia), restlessness and drowsiness.

Risperidone (Risperdal), olanzapine (Zyprexa) and quetiapine (Seroquel) have fewer side effects but still should be used with caution, as they may also worsen symptoms.

• Other medications that may help suppress involuntary movements include amantadine (Gocovri ER, Osmolex ER), levetiracetam (Keppra, Elepsia XR, Spritam) and clonazepam (Klonopin). However, side effects may limit their use.

Medications to treat psychiatric disorders will vary depending on the disorders and symptoms, and may include antidepressants, antipsychotics or mood stabilising drugs. 

Patients may benefit from psychotherapy, speech therapy, physical therapy or occupational therapy in the management of the condition and complications. 

There are support groups for people with Huntington’s disease and their families to help them cope with the challenges of the disease.

• Genetic counselling and family planning options can help people with a known family history of Huntington’s disease who are concerned about passing on the condition to their children.