Huntington’s Disease vs. Parkinson’s Disease: What Are the Differences?

Parkinson’s disease and Huntington’s disease are both neurodegenerative diseases. These types of diseases occur when nerve cells in the brain or peripheral nervous system deteriorate and die off over time.

While there is some overlap between Parkinson’s and Huntington’s, in that they both affect movement, there are distinct differences. The main difference between these diseases is in their genetic makeup.

Huntington’s is an inherited disorder caused by a genetic abnormality. Parkinson’s occurs when the nerve cells in the brain don’t produce enough dopamine, which can be caused by a combination of genetic and environmental factors.

Learn more about the different symptoms, causes, diagnosis, and treatment for these conditions.

Symptoms

With neurodegenerative illness, affected nerve cells can produce a variety of symptoms, including involuntary movement, trembling in the hands, poor balance and coordination, and difficulty making decisions or learning new information.

Both Huntington’s and Parkinson’s can cause symptoms that affect movement. Cognitive decline or dementia can also occur in both.

Though Huntington’s and Parkinson’s share some symptoms, they have a distinct set of symptoms that differentiate them.

Huntington’s Disease Symptoms

The primary symptoms of Huntington’s disease, which typically develops between the ages of 30 and 50, include:

• Uncontrolled movements
• Abnormal body postures
• Changes in behavior, emotion, judgment, and cognition
• Impaired coordination
• Slurred speech
• Difficulty eating and swallowing

Parkinson’s Disease Symptoms

Parkinson’s disease typically starts around age 70, though it can begin earlier. Its primary symptoms include:

• Tremors: Shaking with a rhythmic back and forth motion
• Rigidity: Stiff muscles that are resistant to movement, remaining tense and contracted
• Bradykinesia: Automatic and spontaneous movement slows, making it difficult to perform simple tasks or routine movements
• Body instability: Impaired balance and changes in posture that can increase the risk of falls

People with Parkinson’s can also experience other symptoms, such as:

• Freezing
• Difficulties with speech and language
• Emotional changes
• Urinary problems or constipation
• Cognitive difficulties
• Fatigue
• Difficulty sleeping
• Dementia

Causes

The primary difference between Huntington’s disease and Parkinson’s disease are their causes. Huntington’s is caused by genetics. For Parkinson’s, the causes are more complex.

What Causes Huntington’s Disease?

Huntington’s disease is caused by a mutation in the HTT gene. The HTT gene is responsible for making the huntingtin protein, which is thought to play an important role in nerve cells of the brain.

In Huntington’s disease, a DNA segment within this gene, called the CAG trinucleotide repeat, is repeated more often than is normal.

What Causes Parkinson’s Disease?

Parkinson’s disease is caused by a combination of genetic, lifestyle, and environmental factors. A deficiency in the chemical dopamine can cause symptoms of Parkinson’s disease.

In about 15% of cases, Parkinson’s occurs in individuals with a family history of the disease, due to gene mutations and alterations that are passed down.

Age is a large risk factor for developing Parkinson’s. People over the age of 60 have the highest risk of developing the disease.

Studies show that men are 1.5 times more likely to develop Parkinson’s than women.

Other environmental risk factors that can lead to Parkinson’s include:

• Head injury
• Geographic location
• Exposure to metals
• Exposure to pesticides and herbicides
• Exposure to toxins such as trichlorethylene (TCE) and polychlorinated biphenyls (PCBs)
  

Diagnosis

Diagnosing Huntington’s and Parkinson’s can take time depending on the presentation of symptoms. Physicians and neurologists can make a diagnosis based on a variety of factors.

Huntington’s Diagnosis

A Huntington’s diagnosis can be achieved through a combination of genetic and neurological testing:

• Genetic testing is the most accurate method to diagnose Huntington’s disease. A test will look at the number of CAG repeats in the HTT gene to determine if Huntington’s is present.
• Neurological exams can assist a diagnosis of Huntington’s. This involves taking a full medical and family history, as well as testing reflexes, balance, and movement.
• Brain imaging, such as an MRI or CT scan, may also be conducted to look for abnormalities.
  

Parkinson’s Diagnosis

Diagnosing Parkinson’s disease can be difficult, especially during the early stages of the disease. However, physicians can come to a reasonable conclusion of Parkinson’s if a patient experiences two of the following major symptoms over a period of time:

• Tremors
• Rigidity
• Bradykinesia
• Body imbalance

Treatment

While there is no cure for Huntington’s or Parkinson’s disease, starting and maintaining a treatment plan can help manage the disease and maintain a strong quality of life for as long as possible.

Most treatment plans are focused on controlling symptoms.

Huntington’s Treatment

Unfortunately, there are currently no treatments that can stop or reverse Huntington’s disease. There are, however, medications that can help with movement issues and the emotional issues that come with a diagnosis.

Symptoms of Huntington’s can be treated through various medications. These can include:

• Tetrabenzine, which is used to control involuntary movements, is one of the most common and best ways to treat Huntington’s.
• Deutetrabenazine can also help treat involuntary movements.
• Antipsychotics may help with involuntary movements, but can also control hallucinations and violent outbursts.
• Antidepressants can help treat depression that may come with a diagnosis.

Parkinson’s Treatment

Treatment for Parkinson’s disease depends on the individual’s symptoms, but the primary treatment for Parkinson’s is medication.

The most common medications used to treat Parkinson’s include:

• Levodopa, the main drug treatment for Parkinson’s, increases the levels of dopamine in the brain.
• Carbidopa is often taken with levodopa to control side effects from levodopa and to reduce the amount of levodopa needed to help with symptoms.
• Amantadine is an antiviral drug that can reduce involuntary movements.
• Anticholinergic drugs can be used to reduce tremors.

Other treatments for Parkinson’s disease include deep brain stimulation to help with tremors and rigidity, and therapies such as physical, occupational, and speech therapy to help with daily functions.

Eating a healthy diet and exercising to strengthen muscles can also be a part of the treatment plan for Parkinson’s.

Prevention

Though studies on Huntington’s and Parkinson’s disease are ongoing, prevention is unlikely.

Because Huntington’s disease is genetic, an individual can’t stop the disease from occurring.

Due to the complex nature of Parkinson’s disease and its causes, preventative factors are being explored. One of these is exercise, which has been shown to have some benefits in preventing Parkinson’s.

A Word From Verywell

A diagnosis of Huntington’s or Parkinson’s disease can be upsetting and create challenges in your life. Staying informed, talking to your physician about treatment options to manage symptoms, as well as connecting with others who are going through similar experiences, can help you live well with either disease. Both the Parkinson’s Foundation and Huntington’s Disease Society of America offer resources and support, including information and support groups.