Huntington's disease is an inherited medical condition where there is progressive degeneration or breakdown of the nerve cells in the brain. Huntington's disease greatly affects a person's quality of life and commonly causes movement, cognitive and psychiatric disorders. Many patients develop signs and symptoms of Huntington's disease when they are in their 30s to 40s, however, disease can start either earlier or later in life. When this disease starts before the age of 20, then it is known as juvenile Huntington's disease. If the disease starts early, then it commonly results in a different display of symptoms and the progression of the disease is also faster.
Medications help in managing the symptoms of Huntington's disease; however, there is no treatment which can prevent the physical, mental and behavioral deterioration associated with this disease.
Causes of Huntington's Disease
The cause of Huntington's disease is an inherited defect in a single gene. This is an autosomal dominant disorder, which means that an individual needs to have only one copy of the defective gene to develop Huntington's disease. Barring sex chromosomes, an individual inherits one copy from each parent, i.e. two copies of every gene. So, if a parent has a defective Huntington gene, then they could pass either the copy of the defective gene or the healthy gene. So, there is a 50% chance of inheriting the gene for every child.
Signs & Symptoms of Huntington's Disease
Patient commonly experiences cognitive, movement and psychiatric disorders with a broad range of signs and symptoms. Which symptoms the patient experience's first varies among different patients. There are some symptoms which appear to be more dominant and have an increased effect on functional capacity of the patient. Weight loss is a common symptom of Huntington's disease, especially as the disease worsens.
Huntington's disease causes movement disorders, which are both voluntary and involuntary impairments:
- Patient experiences writhing movements or involuntary jerking (chorea).
- Slow or abnormal movements of the eyes.
- Patient experiences dystonia, which are muscle problems, such as muscle contracture or rigidity.
- Difficulty in speaking or swallowing.
- Patient has impairment of posture, gait and balance.
Any type of impairment or disorder in the voluntary movements disrupts a patient's quality of life more than impairment of involuntary movements. As any problem with voluntary movements affects a person's ability to perform daily activities, work, communication and basically restricts the patient in remaining independent.
- Patient has difficulty in prioritizing, organizing, or concentrating on tasks.
- Patient gets stuck on a behavior, thought or action.
- Decreased control on the patient's impulsive behavior, which can cause in acting without thinking, outbursts and sexual promiscuity.
- Patient has difficulty in processing thoughts or in finding words.
- Patient is not aware of one's own abilities and behaviors.
- There is difficulty in learning any new information.
Depression is the most common psychiatric disorder of Huntington's disease and this appears to occur due to injury to the brain and the following changes in functioning of the brain. Patient experiences the following symptoms:
- Patient becomes socially withdrawn.
- Patient feels sad, irritable or apathetic.
- Patient is not able to sleep.
- Patient feels easily fatigued and doesn't seem to have much energy.
- Patient gets frequent thoughts of dying, death or suicide.
Other psychiatric disorders which the patient experiences are:
- Mania, in which the patient becomes hyperactive, has elevated mood, experiences impulsive behavior and has an inflated ego or self-esteem.
- Obsessive-compulsive disorder is a condition where the patient performs repetitive behaviors and has recurrent and intrusive thoughts.
- Bipolar disorder is when the patient has alternating episodes of mania and depression.
Symptoms of Juvenile Huntington's Disease
The onset and progression of Huntington's disease in younger people is slightly different from the adults. Symptoms experienced early on in the disease by the patient with Juvenile Huntington's include:
- Patient forgets previously learned academic or physical skills or is not able to mentally and physically perform as before.
- There is significant and rapid decrease in the overall performance at school.
- Patient has various behavioral problems.
- Patient has rigid and contracted muscles, which affect the gait, particularly in young children.
- Patient experiences slight involuntary movements or tremors.
- There are changes in fine motor skills, such as handwriting.
- Patient also has seizures.
Consult your doctor as soon as there are changes in the movements, mental ability or emotional state. A number of different conditions can also cause the signs and symptoms of Huntington's disease and it is important to get an immediate diagnosis.
Investigations for Huntington's Disease
For confirming the diagnosis of Huntington's disease, the doctor will ask for the patient's medical history and will conduct a physical, neurological and psychiatric exam.
The neurologist will conduct some simple tests to assess the following:
- Muscle strength.
- Muscle tone.
- Vision and eye movement.
- Sense of touch.
- Changes in mood.
- Changes in mental status.
Psychiatric Evaluation for Assessing:
- Patterns of behaviors.
- Emotional state.
- Coping skills.
- Quality of judgment.
- Evidence of substance abuse.
- Signs of disordered thinking.
Neuropsychological Testing for Assessing:
- Language function.
- Mental agility.
- Spatial reasoning.
Brain Imaging tests are ordered for assessing function or structure of the brain which include:
- MRI (Magnetic Resonance Imaging) which produces detailed 3-D images and cross-sectional images of the brain.
- CT (Computed Tomography) scan, which generates cross-sectional images.
These imaging tests help in revealing any structural changes in specific parts of the brain which are affected by Huntington's disease; although, these changes may not be clearly seen in the initial stages of the disease. However, these tests can also help in ruling out other medical conditions which may be producing symptoms similar to Huntington's disease.
Genetic Testing & Counseling
Genetic testing for the defective gene is done if symptoms strongly suggest a diagnosis of Huntington's disease. The test will only help in confirming the diagnosis and is not suggestive of any treatment plan as such.
Genetic counseling is done to explain the benefits and drawbacks of learning the test results. The counselor will also explain about Huntington's disease and its inheritance patterns.
Predictive Genetic Testing
Predictive genetic testing is done for someone who has a family history of Huntington's disease, but does not display any symptoms. The test result does not give any treatment benefit; also it doesn't indicate when the disease will start or what symptoms will appear first. Often those individuals who find not knowing more stressful go for this type of test and also people undergo predictive genetic testing before making a decision about having children.
Treatment for Huntington's Disease
Medications help in alleviating some of the signs and symptoms of psychiatric disorders; however, there isn't any treatment which changes or affects the course of Huntington's disease. There are multiple interventions which can be undertaken for helping the patient to adapt to changes caused by their disabilities for some amount of time.
Depending on the overall treatment goals, medication management changes over the course of the disease. There are also certain medications, which where they alleviate one type of symptoms, will result in side effects which will worsen other symptoms. For this reason, the goals of the treatment and the treatment course will be reviewed and updated on a regular basis.
Medications for Movement Disorders in Huntington's Disease
- Tetrabenazine (Xenazine) is approved specifically by the Food and Drug Administration for suppressing the involuntary writhing and jerking movements (chorea) which is present in Huntington's disease. There is a serious side effect of this medicine, which is triggering or worsening depression and other psychiatric disorders. Other potential side effects include nausea, drowsiness and restlessness.
- Antipsychotic drugs including haloperidol and chlorpromazine contain side effect which suppresses movements. For this reason, they can be given to treat chorea. However, these medications can worsen dystonia or involuntary contractions and rigidity of the muscles.
There are newer antipsychotic drugs, such as risperidone and quetiapine, which have lesser side effects, but nevertheless should be used with caution, as they can exacerbate the symptoms.
- Other medications which help in suppressing chorea include levetiracetam, amantadine and clonazepam. Given at high doses, amantadine can worsen the cognitive disorders associated with Huntington's disease. Other side effects include swelling of the legs and discoloration of the skin. Side effects of levetiracetam are stomach upset, nausea and mood swings. Clonazepam can exacerbate the cognitive side effects associated with Huntington's disease and can cause drowsiness. There is also a high risk of dependence and abuse with clonazepam.
Medications for Psychiatric Disorders
- Antidepressants such as citalopram, fluoxetine, and sertraline helps with the psychiatric disorders of the Huntington's disease and also help with treating obsessive-compulsive disorder. Side effects include diarrhea, nausea, drowsiness and hypotension.
- Mood-stabilizing drugs including anticonvulsants such as valproate, carbamazepine, and lamotrigine help in preventing the highs and lows which are present with bipolar disorder. Some of the common side effects are tremor, weight gain and gastrointestinal problems.
- Antipsychotic drugs including quetiapine, risperidone and olanzapine help in suppressing agitation, violent outbursts and other associated symptoms of mood disorders or psychosis. These drugs however, can cause other movement disorders.
A psychotherapist, psychologist or a clinical social worker provides counseling or talk therapy to the patient to better manage behavioral problems, to cope better, to manage expectations as the disease worsens and also to help in facilitating better communication among the family members.
A physical therapist helps in teaching safe and appropriate exercises which help in increasing the flexibility, strength, balance and coordination of the patient. These exercises also help in maintaining mobility for a long time and helps in cutting down the risk of falling. A physical therapist also teaches the patient the appropriate posture and how to use supports for improving the posture. All this will help in decreasing the severity of the movement problems. When the patient needs to use the walker or a wheelchair, then the physical therapist will give instructions on posture and the right use of these devices. The physical therapist will also adapt or modify different exercise regimens to suit the patient's new level of mobility.
Huntington's disease greatly impairs the control of the mouth and throat muscles, which are important for speech/talking, eating and swallowing. A speech therapist also helps in improving the speech and also helps the patient in using communication devices, which include a board which is covered with pictures of everyday activities and items. Speech therapists also help with difficulties with the muscles used in swallowing and eating.
An occupational therapist helps patient and his/her family members or caregivers by instructing on the use of assistive devices, which help in improving functional abilities. These strategies may include:
- Assistive devices can be used for activities, such as dressing and bathing.
- Handrails can be used at home.
- Utensils for drinking and eating can be adapted for those patients who have limited fine motor skills.
Lifestyle & Home Remedies for Huntington's Disease
- Patients suffering from Huntington's disease commonly lose weight. Problem with eating, physical exertion or other unknown metabolic problems increases the requirement for higher calories. For providing adequate nutrition, patient needs to consume more than three meals a day.
- Patient has problems chewing, eating, swallowing and with other fine motor skills. This restricts the quantity of food which the patient consumes and also increases the risk of choking. For this reason, patient should be given foods that are easier to eat and the caregiver should also remove any other distractions during a meal, so that the patient can eat undisturbed.
- Utensils which are designed for patients with limited fine motor skills should be used along with cups which have drinking spouts or with straws. As the disease progresses, patients will require assistance with eating and drinking.
For managing cognitive and psychiatric disorders, family members and caregivers should create an environment which helps the patient to avoid stressors and to manage behavioral and cognitive challenges. To assist in this, the following strategies can be used:
- Tasks should be initiated using reminders or other assistance.
- Regular routine can be maintained with the help of calendars and schedules.
- Family members should segregate the daily tasks into small, easy and manageable steps.
- Work or activities should be prioritized or organized, such that the patient is easily able to do them.
- Patient's environment should be kept simple, calm and organized.
- For young kids or adolescents, counseling should be done with the school staff for developing an appropriate education plan for the patients.
- Family members or caregivers should identify and avoid stressors, which can trigger irritability, outbursts, depression or other such problems in the patient.
- The patient should be provided opportunities and given chances for maintaining social interactions and friendships with other people.