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Parkinson’s disease is a neurological condition that gets progressively worse over time and causes trouble with movement. It’s thought to affect about 1 percent of people over the age of 65.

Parkinson’s is caused by the death of cells in a part of your brain called the substantia nigra. When these cells die, levels of the neurotransmitter dopamine drop in your brain. This reduction leads to symptoms such as tremors, impaired balance, rigid muscles, and difficulty walking. Collectively these symptoms are known as parkinsonism.

Parkinson’s disease is attributed to about 85 percent of parkinsonism cases. The other 15 percent of cases are attributed to one of several conditions called atypical parkinsonisms.

Learn about the different types of Parkinson’s and how they’re diagnosed.

Idiopathic Parkinson’s, or simply Parkinson’s disease, is the most common cause of parkinsonism. It generally onsets between the ages of 55 to 65 and rarely occurs before the age of 50.

Parkinson’s onsets gradually as cells in the substantia nigra die and dopamine levels drop. It’s thought genetic and environmental factors contribute to the development of Parkinson’s.

The main symptoms of Parkinson’s disease include:

Juvenile Parkinson’s is a rare condition that onsets before the age of 21. It’s referred to as young-onset Parkinson’s if it presents before the age of 40.

Symptoms are similar to late-onset Parkinson’s, but it’s more likely to be associated with genetic causes than late-onset Parkinson’s. A 2017 study of 108 people with early-onset Parkinson’s found that 46.3 percent reported a family history.

Drug-induced parkinsonism is the second most common cause of parkinsonism. It occurs when a drug interferes with dopamine transmission in your body.

You become more likely to develop drug-induced parkinsonism with age. In a study published in Movement Disorders, researchers found the average age of onset of drug-induced parkinsonism was 70.9.

Symptoms are similar to those of Parkinson’s disease, including:

  • tremor
  • rigidity
  • slowness of movement
  • gait disturbance

Drugs that can lead to drug-induced parkinsonism include:

Multiple system atrophy is a rare disorder that causes similar symptoms as Parkinson’s such as impaired movement, stiff muscles, and poor balance. It most often onsets in your mid-50s.

It can lead to changes in areas such as your:

  • heart rate
  • digestion
  • blood pressure
  • bladder control

Progressive supranuclear palsy causes problems with balance, walking, swallowing, eye movement, speech, and mental ability. For most people, it onsets in their mid-60s and it tends to progress more rapidly than Parkinson’s disease.

The exact cause isn’t known, but symptoms are caused by a deterioration of cells in your brain stem, substantia nigra, and other parts of your brain.

Corticobasal syndrome is caused by a buildup of a type of protein called tau in your brain. Symptoms vary but can include:

  • trouble controlling a limb on one side of your body
  • muscle stiffness
  • tremors
  • jerky movement
  • spasms
  • slow or slurred speech
  • symptoms of dementia
  • trouble swallowing

It usually onsets between the ages of 50 to 70.

Dementia with Lewy bodies is a progressive condition associated with an abnormal buildup of a protein called Lewy bodies, or alpha-synuclein, in your brain. It typically onsets after the age of 50 and affects men slightly more often than women.

Dementia with Lewy bodies also has the same movement symptoms of Parkinson’s, as well as mental symptoms such as:

Vascular parkinsonism is thought to be caused by multiple small strokes in the area of your brain that control movement. It can lead to similar symptoms as Parkinson’s but tends to mostly affect the lower body.

  • postural instability
  • mostly lower-body parkinsonism
  • shuffling or freezing gait when walking
  • absence of a resting tremor
  • poor response to medication levodopa

Because your risk of having a stroke increases with age, your chance of developing vascular parkinsonism is also thought to increase as you get older.

Normal pressure hydrocephalus is a buildup of cerebrospinal fluid in the cavities in your brain. This buildup can put pressure on your brain and cause damage that leads to parkinsonism.

Hydrocephalus is most common in adults over 65.

The average age of onset is approximately 70 years.

  • About 80 to 95 percent of people experience gait disturbances described as shuffling, magnetic, or a wide-based gait.
  • About 80 to 95 percent of people also experience cognitive changes such as reduced attention, forgetfulness, or poor executive function.
  • About 50 to 75 percent of people experience loss of bladder control.

A doctor trained in neurogenerative conditions diagnoses Parkinson’s based on your symptoms, medical history, and results from a physical and neurological test.

No single test can diagnosis Parkinson’s disease, but tests may be able to rule out other causes of parkinsonism. These tests include:

  • Blood test. Blood tests can’t identify Parkinson’s disease directly, but they may be able to help your doctor identify other causes of parkinsonism, such as multiple system atrophy or corticobasal degeneration.
  • Genetic testing. Genetic testing may help your doctor identify the underlying cause of your parkinsonism if you have a family history of parkinsonism.
  • DaTscan. A DaTscan is an imagining technique that lets a doctor see how much dopamine is in your brain. If the scan finds an abnormally low amount, it can help confirm your doctor’s Parkinson’s diagnosis.
  • Magnetic resonance imagining (MRI). An MRI can potentially identify a brain tumor, normal pressure hydrocephalus, or vascular parkinsonism.

Parkinson’s disease and most other causes of parkinsonism have no known cure. But researchers are continuing to learn more about these conditions and how to best control symptoms.

Medications such as levodopa can often dramatically improve symptoms in parkinsonism. Lifestyle changes such as eating a balanced diet, exercising regularly, and undergoing physical therapy can also keep symptoms under control and improve your quality of life.