Huntington’s disease is a hereditary and progressive neurodegenerative disorder characterized by uncontrolled movement, mental instability, and the loss of cognitive function. Once motor symptoms appear, Huntington’s is commonly divided into five stages of disease progression.
Note that symptoms can vary, both from person to person and within any one individual throughout the course of the disease.
The preclinical stage
In most cases, Huntington’s can be officially diagnosed when a person first begins to experience motor symptoms. However, some individuals may experience subtle changes in cognition and behavior — such as unusual irritability, anxiety, or depression — seven to 10 years before motor symptoms begin. This preclinical stage of the disease is sometimes called its prodromal phase. During this stage, individuals do not fulfill diagnostic criteria for Huntington’s, but do exhibit signs and symptoms indicating a greater risk for the disease.
Stage 1: Early stage
The early stage starts when a person first begins experiencing motor symptoms, and can last up to eight years from disease onset. At this stage, motor symptoms are not debilitating. Most individuals in the early stage are fully functional at home and at work, and usually maintain typical pre-disease levels of independence when it comes to everyday activities such as finances, home responsibilities, and activities of daily living such as eating, dressing, and bathing. Mild cognitive symptoms and psychiatric changes may begin to occur among individuals at this disease stage.
Stage 2: Early intermediate stage
The early intermediate stage of Huntington’s can last between three and 13 years from disease onset. During this stage, patients begin to experience impairments in day-to-day living. For instance, people in the early intermediate stage may be able to do their job, but at a lower capacity. Individuals at this stage may find that some daily activities are more difficult, and may require assistance with some aspects of daily tasks. Chorea, which is irregular involuntary movement in multiple areas of the body, may become more severe at this stage.
Stage 3: Late intermediate stage
The late intermediate stage usually lasts between five and 16 years from disease onset. An individual at this stage is no longer able to work or manage household responsibilities. A patient’s ability to think also may become more impaired, and he or she will require substantial help for daily financial affairs, domestic responsibilities, and activities of daily living. Psychiatric and behavioral symptoms, including irritability, anxiety, and impulsiveness may become evident. In general, cognitive, psychiatric, and motor features worsen at this stage.
Stage 4: Early advanced stage
Typically lasting between nine and 21 years from disease onset, the early advanced stage is characterized by a need for full assistance in daily living. A person in this stage of Huntington’s cannot live independently. Some patients reside in their home with help from either family or professionals, while other individuals may decide that their needs will be better met at an extended care facility. A person in this stage of disease will be aware of daily living activities that have to be done, but will require major assistance to do them.
Stage 5: Advanced stage
The advanced stage lasts between 11 and 26 years from disease onset. Patients with Huntington’s at this late stage will need total support in daily activities from professional nursing care. Chorea lessens at this stage, but parkinsonism — which includes slowness, stiffness, teeth grinding, and abnormal limb postures — increases. Walking/mobility, and a person’s ability to maintain an upright posture also worsen, and there is an increased risk of falls.
Speech can become difficult at this stage and the patient may go through periods of confusion and screaming. The ability to swallow also can worsen, and there can be extreme fluctuations in blood pressure and temperature.
Patients with Huntington’s disease usually die an average of 10-20 years after symptoms first appear. The cause of death usually is a complication of Huntington’s, the most common of which is aspiration pneumonia — an infection caused by unintentional inhaling of food. Suicide is the second leading cause of death.
Variability in disease severity and progression
It is thought that the variability in disease severity and rate of progression among people with Huntington’s is linked to the genetic mutation causing the disease.
Huntington’s is caused by a mutation in the HTT gene. This mutation is in the form of a CAG trinucleotide repeat expansion. Although the exact reason for this is unknown, multiple studies have suggested that the number of the CAG repeats is inversely correlated with the age of onset of the symptoms and disease severity. That means that patients with fewer CAG repeats tend not to experience symptoms of the disease until they are older, and once symptoms do appear, they are generally less severe and worsen more slowly. Conversely, a greater number of CAG repeats is linked to earlier onset of symptoms, which worsen more quickly.
Last updated: Aug. 9, 2021
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