Huntington's disease is an inherited disease that causes the progressive breakdown (degeneration) of nerve cells in the brain. Huntington’s disease has a wide impact on functional abilities, which usually results in movement, thinking (cognitive) and psychiatric disorders.
The onset of the disease may be earlier or later in life but most people develop symptoms in their 30s or 40s. If the disease onset begins before age 20 it’s called juvenile Huntington’s disease. Earlier onset may have a different presentation of symptoms and faster disease progression.
There is no cure for Huntington’s disease. There are medications to manage the symptoms but treatments cannot prevent the physical, mental and behavioural decline as the condition progresses.
Symptoms
Huntington’s disease typically causes movement, cognitive and psychiatric disorders that may present with a variety of symptoms.
Movement disorders
- Involuntary jerking or writhing movements (chorea)
- Muscle problems such as rigidity or muscle contracture (dystonia)
- Slow or abnormal eye movements
- Impaired gait, posture and balance
- Difficulty speaking or swallowing
Cognitive disorders
- Difficulty organizing, prioritizing or focusing on tasks
- Lack of flexibility or the tendency to get stuck on a thought, behavior or action (perseveration)
- Lack of impulse control that can result in outbursts and sexual promiscuity
- Lack of awareness of one’s own behaviors and abilities
- Slowness in thought processing
- Difficulty learning new information
Psychiatric disorders
- Depression
- Irritability, sadness or apathy
- Social withdrawal
- Insomnia
- Fatigue and loss of energy
- Frequent thoughts of death, dying or suicide
Other psychiatric disorders:
- Obsessive-compulsive disorder (recurrent, intrusive thoughts and repetitive behaviors)
- Mania (elevated mood, overactivity, impulsive behavior and inflated self-esteem)
- Bipolar disorder or altering episodes of depression and mania
In addition, weight loss is also a common symptoms of Huntington’s disease, especially when the disease progresses.
Symptoms of juvenile Huntington’s disease
Behavioral changes
- Loss of previously learned academic or physical skills
- Rapid, significant drop in overall academic performance
- Behavioral problems
Physical changes
- Contracted and rigid muscles that affect gait
- Changes in fine motor skills (noticeable in handwriting)
- Tremors or slight involuntary movements
- Seizures
Causes
Huntington’s disease is an inherited disorder caused by a defect in a single gene. The disease is an autosomal dominant disorder meaning that one copy of the defective gene is enough to develop the disorder. One parent carrying the defective gene can pass it to the children. Therefore, each child has a 50% chance of inheriting the gene that causes Huntington’s disease.
Complications
After the onset of Huntington’s disease, the functional abilities gradually worsen over time. The rate of disease progression and duration can vary. The time from disease onset to death is usually about 10 to 30 years. Juvenile onset typically results in death within 10 years.
As the disease progresses, the person requires help with all daily activities and care. In the late stages of the disease the person is likely to be confined to a bed and unable to speak. However, the person is usually able to understand language and has awareness of family and friends.
Common causes of death include:
- Pneumonia or other infections
- Injuries related to falls
- Complications associated with the inability to swallow
Prevention
A family history of Huntington’s disease raises concerns about future options and passing the Huntington gene onto children. Genetic testing can reveal the possibility of the parent developing the disease and passing it on to children.
