“Idiopathic” means that a health condition has no identifiable cause. Most diagnoses of Parkinson’s disease are idiopathic. Risk factors include older age and being assigned male at birth.

Parkinson’s disease is a progressive neurological disorder that affects movement, but it can also have a wide range of non-motor symptoms as well.

Most diagnoses of Parkinson’s disease are idiopathic, which means that there’s no known cause.

To diagnose idiopathic Parkinson’s disease (IPD), a doctor must carefully rule out other conditions that cause similar symptoms.

This article reviews IPD in more detail, including symptoms, who’s at risk, and how it’s diagnosed and treated.

Language matters

You’ll notice that the language used to share stats and other data points is pretty binary, especially with the use of the term “male.”

Although we typically avoid language like this, specificity is key when reporting on research participants and clinical findings.

Unfortunately, the source referenced in this section didn’t report data on, or include, participants who were transgender, nonbinary, gender nonconforming, genderqueer, agender, or genderless.

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When Parkinson’s disease has no identifiable cause, the condition is diagnosed as IPD. It makes up most diagnoses of Parkinson’s disease.

Parkinson’s disease has a known genetic cause in only 10–15% of people. These individuals often develop Parkinson’s disease at an earlier age than those with IPD.

Idiopathic Parkinson’s disease vs. parkinsonism

Parkinsonism” is an umbrella term for conditions that lead to movement difficulties similar to those seen in Parkinson’s disease. You may also see some of these conditions called “Parkinson’s plus.” Examples are:

Additionally, secondary parkinsonism can develop from a variety of known factors, such as exposure to certain drugs (drug-induced parkinsonism) and cerebrovascular disease (vascular parkinsonism).

According to the Parkinson’s Foundation, it’s difficult to know early on if an individual has IPD or if there’s a known cause of parkinsonism due to their similar symptoms. Unlike IPD, other causes of parkinsonism tend to:

  • progress more quickly
  • present with additional signs and symptoms, including:
  • affect both sides of the body initially as opposed to one side
  • not respond well to treatment with levodopa (Sinemet), a commonly used drug for Parkinson’s disease

In IPD, nerve cells in the brain are damaged and expire. The buildup of the protein alpha-synuclein in Lewy bodies inside nerve cells is believed to contribute to this damage. What causes Lewy bodies to form isn’t known.

The substantia nigra is the most commonly affected area of the brain in IPD. This part of the brain is important for controlling movement and contains many dopamine-producing nerve cells. Dopamine is a neurotransmitter that helps control muscle tone and movement. A loss of dopamine results in the main symptoms of Parkinson’s disease.

Some of the potential risk factors for IPD include:

The three main symptoms of Parkinson’s disease, including IPD, are:

Over time, postural instability may also develop in which changes in posture and gait due to IPD affect your balance and increase the risk of falls.

There are also a variety of non-motor symptoms and signs that can happen with Parkinson’s disease, including:

There’s no specific test that can definitively diagnose IPD.

A doctor will aim to rule out other causes of your symptoms, such as medications or other neurological disorders, to make the diagnosis. This process is typically accomplished by:

  • doing a thorough physical and neurological exam, during which they’ll check your:
    • movement
    • balance
    • posture
    • muscle tone
    • speech
    • mental status
  • getting a detailed medical history, including information like:
    • details about your symptoms, such as when they started, how severe they are, and if anything makes them better or worse
    • any medications you’re taking
    • any preexisting health conditions
    • certain health conditions that may run in your family

Other tests, such as blood tests and imaging tests, may also be used to help rule out other causes of your symptoms.

Response to levodopa treatment can also point to a diagnosis of Parkinson’s disease. This is because other conditions, such as other causes of parkinsonism, typically don’t respond well to this medication.

IPD is typically treated using medications. These medications work by affecting the levels of dopamine in the brain to ease the motor symptoms of IPD. Levodopa is one of the most commonly used medications for IPD.

If you have IPD, you may also be prescribed other medications as well. These may be geared toward reducing non-motor symptoms, such as depression, constipation, or sexual dysfunction.

Nonmedical treatments are also an important part of IPD treatment. These treatments may include:

When IPD symptoms have become very severe or medications aren’t effective, deep brain stimulation may be an option. This procedure involves using surgically implanted electrodes to stimulate certain areas of the brain.

There’s no cure for IPD. Instead, treatment focuses on easing symptoms and improving quality of life.

IPD is progressive, which means that it gradually gets worse over time. It’s estimated that Parkinson’s disease leads to recognized disability in most people within 10 years.

Each person with IPD is different, so it can be challenging to predict exactly how IPD will progress from person to person.

The life expectancy of people with Parkinson’s disease is generally the same as that of the general population.

A 2018 study did see reduced life expectancy for people with idiopathic disease but noted that this finding was dependent on the specific characteristics of the condition. For example, individuals without cognitive difficulties had a typical life expectancy.

Most diagnoses of Parkinson’s disease are idiopathic, which means that there isn’t an identifiable cause. Only a small number of Parkinson’s disease diagnoses are caused by known genetic factors.

To diagnose IPD, a doctor must rule out other conditions that cause similar symptoms, such as other causes of parkinsonism. To do this process, they’ll carefully check your symptoms and medical history.

Treatment of IPD involves medications and potentially nonmedical treatments, like physical therapy or psychotherapy. There’s currently no cure for IPD. The progression and outcome of IPD can vary between individuals.