Huntington's disease is associated with decreased serotonin and GABA. Decreased levels of serotonin affect memory and learning abilities. Decreased GABA causes increased dopamine and presents as chorea, which is defined by excessive and abnormal involuntary movements. The disease may also increase levels of glutamate, an excitatory neurotransmitter and contribute to excessive motor movements.
Symptoms of Huntington's disease normally appear around age 40. If the patient is symptomatic, genetic testing may be done to confirm the disease. Aspiration pneumonia and heart disease are the leading causes of death, which usually occurs 10 to 20 years after onset of symptoms.
This progressive, degenerative brain disorder may cause slow cognitive decline and eventually develop into dementia. Decreased levels of serotonin may lead to memory and learning impairments. The patient's perception, memory, attention span, and ability to learn deteriorates as the disease progresses. The abilities to eat and talk decreases and creates frustration for the patient.
The increased levels of dopamine cause choreiform movements in the face, limbs, and body that are difficult to control. As the disease progresses, the movements worsen and ambulation gradually becomes impossible.
Increased levels of dopamine result in the non repetitive jerks seen in patients with Huntington's disease. These movements are characterized as odd, uncontrollable, and excessive. The amount of non repetitive jerking movements increases as the disease progresses.
Neuroleptics, such as haloperidol and risperidone, may be used to decrease the symptoms of Huntington's disease by blocking dopamine receptors and decreasing choreiform movements. However, these medications do not slow down disease progression.
Excessive levels of dopamine cause chorea in patients with Huntington's disease. Tetrabenazine decreases dopamine transmission in the brain to significantly moderate chorea.
Since Huntington's disease is an autosomal dominant disorder, genetic counseling is recommended to confirm the presence of disease. A positive test indicates that a person will develop the disease but the timing and extent is unknown. DNA testing may be done on fetal cells retrieved by amniocentesis or chorionic villus sample. Since there is no cure for Huntington's disease, genetic counseling of expectant families is the only method of decreasing prevalence of the disease.
Huntington's disease is a progressive condition that is classified in stages. Each of the three stages lasts about 5 years. During stage 1, the patient may present with psychological and neurological deficits but is able to maintain independence. During stage 2, the patient may experience increased choreiform movements and will require assistance with ADLs. The majority of patients in stage 3 of Huntington's disease are completely dependent on others to perform ADLs.
Huntington's disease causes choreic movements that increase the patient's caloric requirements. In order to maintain body weight, the patient may need up to 5000 calories/day. As the disease progresses, maintaining nutritional requirements may necessitate a switch to pureed foods or thickened liquid diets since patients may have increased difficulty swallowing.
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