Disease: Huntington's disease

Overview

Huntington's disease is an inherited disease that causes the progressive breakdown (degeneration) of nerve cells in the brain. Huntington's disease has a broad impact on a person's functional abilities and usually results in movement, thinking (cognitive) and psychiatric disorders.

Most people with Huntington's disease develop signs and symptoms in their 30s or 40s. But the disease may emerge earlier or later in life.

When the disease develops before age 20, the condition is called juvenile Huntington's disease. An earlier emergence of the disease often results in a somewhat different set of symptoms and faster disease progression.

Medications are available to help manage the symptoms of Huntington's disease, but treatments can't prevent the physical, mental and behavioral decline associated with the condition.

Huntington's disease care at Mayo

Source: http://www.mayoclinic.com

Symptoms

Huntington's disease usually causes movement, cognitive and psychiatric disorders with a wide spectrum of signs and symptoms. Which symptoms appear first varies greatly among affected people. During the course of the disease, some disorders appear to be more dominant or have a greater effect on functional ability.

Movement disorders

The movement disorders associated with Huntington's disease can include both involuntary movement problems and impairments in voluntary movements, such as:

  • 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 with the physical production of 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 disorders

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, behavior or action (perseveration)
  • Lack of impulse control that can result in outbursts, acting without thinking and sexual promiscuity
  • Lack of awareness of one's own behaviors and abilities
  • Slowness in processing thoughts or ''finding'' words
  • Difficulty in learning new information

Psychiatric disorders

The most common psychiatric disorder associated with Huntington's disease is depression. This isn't simply a reaction to receiving a diagnosis of Huntington's disease. Instead, depression appears to occur because of injury to the brain and subsequent 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 — a condition marked by recurrent, intrusive thoughts and repetitive behaviors
  • Mania, which can cause elevated mood, overactivity, impulsive behavior and inflated self-esteem
  • Bipolar disorder — a condition with alternating episodes of depression and mania

In addition to the above symptoms, weight loss is common in people with Huntington's disease, especially as the disease progresses.

Symptoms of juvenile Huntington's disease

The start and progression of Huntington's disease in younger people may be slightly different from that in adults. Problems that often present themselves early in the course of the disease include:

Behavioral changes

  • Loss of previously learned academic or physical skills
  • Rapid, significant drop in overall school performance
  • Behavioral problems

Physical changes

  • Contracted and rigid muscles that affect gait (especially in young children)
  • Changes in fine motor skills that might be noticeable in skills such as handwriting
  • Tremors or slight involuntary movements
  • Seizures

When to see a doctor

See your doctor if you notice changes in your movements, emotional state or mental ability. The signs and symptoms of Huntington's disease can be caused by a number of different conditions. Therefore, it's important to get a prompt, thorough diagnosis.

Source: http://www.mayoclinic.com

Causes

Huntington's disease is caused by an inherited defect in a single gene. Huntington's disease is an autosomal dominant disorder, which means that a person needs only one copy of the defective gene to develop the disorder.

With the exception of genes on the sex chromosomes, a person inherits two copies of every gene — one copy from each parent. A parent with a defective gene could pass along the defective copy of the gene or the healthy copy. Each child in the family, therefore, has a 50 percent chance of inheriting the gene that causes the genetic disorder.

Source: http://www.mayoclinic.com

Diagnosis

A preliminary diagnosis of Huntington's disease is based primarily on your answers to questions, a general physical exam, a review of your family medical history, and neurological and psychiatric examinations.

Neurological examination

The neurologist will ask you questions and conduct relatively simple tests in the office to judge:

Motor symptoms

  • Reflexes
  • Muscle strength
  • Muscle tone
  • Coordination
  • Balance

Sensory symptoms

  • Sense of touch
  • Vision and eye movement
  • Hearing

Psychiatric symptoms

  • Mental status
  • Mood

Neuropsychological testing

The neurologist may also perform standardized tests to assess:

  • Memory
  • Reasoning
  • Mental agility
  • Language function
  • Spatial reasoning

Psychiatric evaluation

You'll likely be referred to a psychiatrist for an examination to judge a number of factors that could contribute to your diagnosis, including:

  • Emotional state
  • Patterns of behaviors
  • Quality of judgment
  • Coping skills
  • Signs of disordered thinking
  • Evidence of substance abuse

Brain imaging and function

Your doctor may order brain-imaging tests for assessing the structure or function of the brain. The imaging technologies may include magnetic resonance imaging (MRI) or computerised tomography (CT) scans that provide detailed images of brain structures.

These images may reveal structural changes at particular sites in the brain affected by Huntington's disease, although these changes may not be apparent early in the course of the disease. These tests can also be used to rule out other conditions that may be causing symptoms.

Genetic counseling and testing

If symptoms strongly suggest a diagnosis of Huntington's disease, your doctor may recommend a genetic test for the defective gene.

This test can confirm the diagnosis, and it may be valuable if there's no known family history of Huntington's disease or if no other family member's diagnosis was confirmed with a genetic test. But the test won't provide information that might help determinine a treatment plan.

Before undergoing such a test, the genetic counselor will explain the benefits and drawbacks of learning test results. The genetic counselor can also answer questions about the inheritance patterns of Huntington's disease.

Predictive genetic test

A genetic test can be given to someone who has a family history of the disease but shows no signs or symptoms. This is called predictive testing. The test result has no treatment benefit, and it doesn't indicate when disease onset will begin or what symptoms are likely to appear first.

Some people may elect to do the test because they find it more stressful not knowing. Others may want to take the test before they make decisions about having children.

Risks may include problems with insurability or future employment and the stresses of facing a fatal disease. In principle, federal laws exist that make it illegal to use genetic testing information to discriminate against people with genetic diseases.

These tests are only performed after consultation with a genetic counselor.

Source: http://www.mayoclinic.com

Complications

After the start of Huntington's disease, 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 has begun 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. However, he or she is generally able to understand language and has an awareness of family and friends.

Common causes of death include:

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

Source: http://www.mayoclinic.com

Prevention

People with a known family history of Huntington's disease are understandably concerned about whether they may pass the Huntington gene on to their children. These people may consider genetic testing and family planning options.

If an at-risk parent is considering genetic testing, it can be helpful to meet with a genetic counselor. A genetic counselor will discuss the potential risks of a positive test result, which would indicate the parent will develop the disease. Also, couples will need to make additional choices about whether to have children or to consider alternatives, such as prenatal testing for the gene or in vitro fertilization with donor sperm or eggs.

Another option for couples is in vitro fertilization and preimplantation genetic diagnosis. In this process, eggs are removed from the ovaries and fertilized with the father's sperm in a laboratory. The embryos are tested for presence of the Huntington gene, and only those testing negative for the Huntington gene are implanted in the mother's uterus.

Source: http://www.mayoclinic.com

Lifestyle and home remedies

Managing Huntington's disease is demanding on the person with the disorder, family members and other in-home caregivers. As the disease progresses, the person will become more dependent on caregivers. A number of issues will need to be addressed, and strategies to cope with them will evolve.

Eating and nutrition

Factors regarding eating and nutrition include the following:

  • People with Huntington's disease often have difficulty maintaining a healthy body weight. Difficulty eating, higher caloric needs due to physical exertion or unknown metabolic problems may be the cause. To get adequate nutrition, more than three meals a day or the use of dietary supplements may be necessary.
  • Difficulty with chewing, swallowing and fine motor skills can limit the amount of food you eat and increase the risk of choking. Problems may be minimized by removing distractions during a meal and selecting foods that are easier to eat. Utensils designed for people with limited fine motor skills and covered cups with straws or drinking spouts also can help.

Eventually, a person with Huntington's disease will need assistance with eating and drinking.

Managing cognitive and psychiatric disorders

Family and caregivers can help create an environment that may help a person with Huntington's disease avoid stressors and manage cognitive and behavioral challenges. These strategies include:

  • Using calendars and schedules to help keep a regular routine
  • Initiating tasks with reminders or assistance
  • Prioritizing or organizing work or activities
  • Breaking down tasks into manageable steps
  • Creating an environment that is as calm, simple and structured as possible
  • Identifying and avoiding stressors that can trigger outbursts, irritability, depression or other problems
  • For school-age children or adolescents, consulting with school staff to develop an appropriate individual education plan
  • Providing opportunities for the person to maintain social interactions and friendships as much as possible

Source: http://www.mayoclinic.com

Coping and support

A number of strategies may help people with Huntington's disease and their families cope with the challenges of the disease.

Support services

Support services for people with Huntington's disease and families include the following:

  • Nonprofit agencies, such as the Huntington's Disease Society of America, provide caregiver education, referrals to outside services, and support groups for people with the disease and caregivers.
  • Local and state health or social service agencies may provide daytime care for people with the disease, meal assistance programs or respite for caregivers.

Planning for residential and end-of-life care

Because Huntington's disease causes the progressive loss of function and death, it's important to anticipate care that will be needed in the advanced stages of the disease and near the end of life. Early discussions about this type of care enable the person with Huntington's disease to be engaged in these decisions and to communicate his or her preferences for care.

Creating legal documents that define end-of-life care can be beneficial to everyone. They empower the person with the disease, and they may help family members avoid conflict late in the disease progression. Your doctor can offer advice on the benefits and drawbacks of care options at a time when all choices can be carefully considered.

Matters that may need to be addressed include:

  • Care facilities. Care in the advanced stages of the disease will likely require in-home nursing care or care in an assisted living facility or nursing home.
  • Hospice care. Hospice services provide care at the end of life that helps a person approach death with as little discomfort as possible. This care also provides support and education to the family to help them understand the process of dying.
  • Living wills. Living wills are legal documents that enable a person to spell out care preferences when he or she isn't able to make decisions. For example, these directions might indicate whether or not the person wants life-sustaining interventions or aggressive treatment of an infection.
  • Advance directives. These legal documents enable you to identify one or more people to make decisions on your behalf. You may create an advance directive for medical decisions or financial matters.

Source: http://www.mayoclinic.com

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