Parkinson’s disease is a degenerative neurological condition, meaning it becomes more severe over time. It affects movement, causing tremors, rigid muscles, and impaired balance.

Parkinson’s disease occurs when brain cells in the substantia nigra region die, impairing communication between neurons. This causes symptoms affecting movement, called Parkinsonism.

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Parkinsonism is the group of symptoms Parkinson’s disease can cause. Symptoms include rigidity (stiffness), slow movement (bradykinesia), tremor, and postural instability or imbalance.

Other conditions may also cause these symptoms, but Parkinson’s disease is the greatest cause of Parkinsonism.

This is the most common type of Parkinsonism, accounting for 85% of cases. It is commonly called Parkinson’s disease. Idiopathic means the cause of the disease is unclear, and it may occur spontaneously.

Parkinson’s disease usually develops between 55–65 years old, and rarely occurs before the age of 50 years. The condition develops gradually. First, nerve cells, which are in structures in the brain called the basal ganglia, begin to die and produce less dopamine. The basal ganglia control movements, making them happen smoothly.

The basal ganglia need dopamine to connect neurons. Lowering dopamine levels within the brain reduces connections and interrupts communications. This means that body movements become less smooth, and tremors and other movement symptoms, such as rigidity, occur.

Major symptoms of Parkinson’s disease include:

  • slowed movement, known as bradykinesia
  • rigidity
  • tremors
  • stooped posture
  • feelings of unsteadiness and difficulty walking
  • difficulty balancing
  • changes in speech, such as slurring

Vascular Parkinsonism is an atypical Parkinsonism. The cause may be multiple minor strokes in important areas of the brain.

There are no tests or clinical features that reliably compare Parkinson’s disease and vascular Parkinsonism. But there are features to suggest a person has vascular Parkinsonism, including a severe onset of Parkinsonism within a year of a stroke, and evidence of vascular disease on an MRI scan of the brain alongside early cognitive problems and issues with balance and gait in the lower body.

Symptoms of vascular Parkinsonism include:

  • no resting tremor, unlike most types of Parkinsonism
  • shuffling gait when walking
  • poor response to the Parkinson’s medication levodopa
  • unstable posture
  • Parkinsonism mostly in the lower body

Drug-induced Parkinsonism is the most common type of secondary Parkinsonism. The symptoms are side effects of certain medications, especially those affecting dopamine levels.

Drug-induced Parkinsonism can be difficult to tell apart from Parkinson’s disease, although the tremors and instability may appear less severe.

Stopping the medications that cause the side effects can make them disappear gradually, although this may take up to a year.

Medications that may cause Parkinsonism to develop include:

  • some antidepressants
  • antipsychotics
  • some antinausea medications, called antiemetics
  • some calcium channel blockers
  • tetrabenazine
  • reserpine

Symptoms drug-induced Parkinsonism shares with Parkinson’s disease include:

  • tremors
  • slow movement
  • rigidity
  • shuffling or awkward gait

Other types of Parkinsonism may also be mistaken for Parkinson’s disease. These include:

Multiple system atrophy (MSA)

MSA refers to several neurodegenerative disorders that cause systems in the body to deteriorate.

MSA usually occurs when a person is in their mid-50s. Clues can indicate MSA, rather than Parkinson’s disease, over time, including poor response to Parkinson’s disease medication and more rapid progression. Diagnosing MSA relies on clinical features, and there is no specific test to identify the condition.

Symptoms include:

  • dysfunction in the autonomic nervous system, which controls blood pressure and bladder function
  • lack of coordination, called ataxia
  • varying degrees of typical Parkinson’s disease symptoms

Progressive supranuclear palsy (PSP)

PSP is the most common degenerative type of atypical Parkinsonism. The average age of onset is the mid-60s.

There is no specific test to diagnose PSP, and no specific treatment.

Symptoms of PSP often progress faster than symptoms of Parkinson’s disease, and people may fall over in the early stages of the disease. Symptoms include:

  • limitations in eye movement, particularly looking up
  • problems swallowing, called dysphagia
  • problems sleeping
  • memory and thinking problems, called dementia
  • difficulty speaking, called dysarthria

Normal pressure hydrocephalus

Hydrocephalus results from cerebrospinal fluid building up in the brain cavities. This can put pressure on the brain, causing Parkinsonism.

The average age of onset is 70 years old.

Common symptoms include:

  • shuffling or wide gait while walking
  • forgetfulness
  • trouble paying attention
  • loss of bladder control

Tremors

Tremors, especially those that occur when a person is relaxing, are a common symptom of Parkinson’s disease. About 75% of people with Parkinson’s experience resting tremors at some point.

Symptoms include:

  • rhythmic shaking in the head, legs, arms, or torso
  • problems holding and controlling utensils
  • shaky voice
  • difficulty writing or drawing

Parkinson’s disease is a diverse disorder that each person experiences differently. The disease affects about 1 million people in the United States, and 10 million globally. Causes of Parkinson’s disease are generally unknown, although research suggests that genetics and environmental factors likely play a role.

For example, evidence notes that genetic mutations, such as in the alpha-synuclein gene, may relate to the condition. Additionally, exposure to certain toxins, such as MPTP or manganese, may result in Parkinsonian symptoms in genetically susceptible individuals.

There is no diagnostic test for Parkinson’s disease or other types of Parkinsonism. Doctors rely on clinical factors to diagnose the disease. Factors include the following:

  • Medical history.
  • Symptoms.
  • Neurological and physical function.
  • DaTscan: Doctors use a phenyltropane injection and a gamma camera to detect and assess dopamine transporter function.
  • PET scan: Similar to a DaTscan, but using positron particles instead of gamma rays.
  • If Parkinson’s disease medication has not been working, this may indicate a different Parkinsonism.
  • MRI scans may reveal the effects of stroke in the brain, which could indicate vascular Parkinsonism.

Common risk factors for Parkinson’s disease include:

  • Genetics: Around 10–15% of people with Parkinson’s have a family history of the condition.
  • Age: People approaching 60 years old and older are at greater risk of the disease.
  • Environmental factors: Environmental risk factors may include exposure to pesticides and air pollution, as well as traumatic brain injury.
  • Sex: Men are twice as likely as women to develop Parkinson’s disease. But the condition progresses faster in women and has a higher mortality rate.

There is currently no cure for Parkinson’s disease, but treatments can help people manage the symptoms.

Medications

Medications that treat Parkinson’s disease include:

  • Carbidopa and levodopa: These can control tremors.
  • Dopamine agonists: While these drugs may not be as effective as carbidopa and levodopa, they may still help stimulate the part of the brain that dopamine influences.
  • Benzodiazepines, or tranquilizers: These may temporarily alleviate tremors.
  • Beta-blockers: A doctor may prescribe these for high blood pressure, but they may also treat Parkinson’s disease.
  • Anti-seizure medication: Medications such as primidone can help those with tremors who do not respond to beta-blockers.
  • Botulinum toxin, or Botox: A doctor may inject this to treat most types of tremor.

Deep brain stimulation (DBS)

DBS is a procedure that involves doctors surgically implanting electrodes in the part of the brain that controls movement. The electrodes connect to a pacemaker-like device, or neurostimulator, which is under the skin on the upper chest. The device then sends electrical impulses along a wire into the brain via the electrodes. These impulses can help prevent symptoms by interfering with the electrical signals that cause them.

Occupational, relaxation, and physical therapy

A physical therapist may help people with tremors to improve their strength and muscle control with balancing, coordination, and relaxation exercises.

There are various types of Parkinsonism. The most common is idiopathic Parkinson’s, or Parkinson’s disease.

Other types, which are atypical Parkinsonism, include vascular and drug-induced Parkinsonism. Less common types include MSA, PSP, and normal pressure hydrocephalus.

Causes of Parkinson’s disease are unclear, but risk factors include age, sex, environment, and genetics.

There is no diagnostic test for Parkinson’s, but doctors use various methods to assess for the disease. Methods include MRI and PET scans, analyzing a person’s symptoms, and physical and neurological exams.

Parkinson’s disease has no cure, but medication, DBS, and physical, occupational, and relaxation therapy can treat the symptoms.