What Is Parkinson’s Disease? Symptoms, Causes, Diagnosis, Treatment, and Prevention

Parkinson’s disease is a movement disorder that happens when nerve cells (neurons) in a certain part of the brain are no longer making the chemical dopamine.

The condition is also sometimes known as paralysis agitans or shaking palsy.

History of Parkinson’s Disease

Parkinson (1755–1824) observed what are now known as the classic symptoms of Parkinson’s disease, including tremors, rigidity, and postural instability. He theorized that the disease developed because of a problem in the brain’s medulla region.

What Is Parkinsonism? Is It Different From Parkinson’s?

No quick or easy diagnostic tests exist for Parkinson’s disease, so a patient may receive an initial diagnosis of parkinsonism without a more specific condition being confirmed.

Signs and Symptoms of Parkinson’s Disease

Some of the most common motor symptoms are:

• Tremors, or shaking movements
• Bradykinesia, or slowed movement that all people with Parkinson’s experience
• Rigidity, or stiffness
• Postural instability, or issues with balance
• Parkinsonian gait (also known as festinating gait) — walking while stooped over, or a combination of freezing and quickening of gait

Among the most common nonmotor symptoms are:

• Cognitive issues like dementia
• Psychosis, or thoughts and beliefs that aren’t rooted in reality
• Mood disorders such as depression and anxiety, or feelings of apathy
• Sleep disorders like insomnia

• Motor Only Symptoms are mainly motor (physical), with intact cognition and psychiatric function.
• Psychiatric and Motor Symptoms are mainly psychiatric, with moderate motor deficits.
• Cognitive and Motor Symptoms are a combination of cognition and motor.

Parkinson’s symptoms often begin on one side of the body and gradually affect both sides of the body, but they tend to be worse on the side they affected first.

Stages of Parkinson’s Disease

• Stage 1 Symptoms are seen on one side of the body only.
• Stage 2 Symptoms are seen on both sides of the body. There’s no impairment of balance.
• Stage 3 Balance impairment has begun. In this mild to moderate stage of the disease, the person is still physically independent.
• Stage 4 This stage is marked by severe disability, but the person is still able to walk or stand unassisted.
• Stage 5 The person requires a wheelchair or is bedridden unless assisted.

The signs and symptoms of Parkinson’s are divided into two categories: motor and nonmotor. Motor symptoms of Parkinson’s affect one’s movement, whereas nonmotor Parkinson’s symptoms are unrelated to movement.

Causes and Risk Factors of Parkinson’s Disease

Most cases of Parkinson’s disease are idiopathic, meaning the cause is unclear.

It’s widely believed that a person with Parkinson’s may be genetically vulnerable to the disease and that one or more unknown factors in the environment eventually triggers it.

Normally, the neurons in this part of the brain make the chemical messenger (neurotransmitter) dopamine, which allows communication with another area of the brain, the corpus striatum.

This communication helps produce smooth, purposeful movement. When the neurons in the substantia nigra die, the resulting loss of communication leads to the motor (movement-related) symptoms of Parkinson’s.

What Are Lewy Bodies?

The affected neurons of people with Parkinson’s disease have been found to contain clumped proteins called Lewy bodies. Researchers aren’t yet sure why Lewy bodies form or what role they play in the disease, but Lewy bodies are believed to be toxic.

Lewy bodies are clumps of a protein called alpha-synuclein. Neurons can’t break down these protein clumps, which may lead to the death of these cells.

What Are the Risk Factors for Parkinson’s Disease?

Risk factors for Parkinson’s disease include:

Genetics

People with a first-degree relative (parent or sibling) with Parkinson’s are at an increased risk for the disease — possibly as much as 9 percent greater. Genetic risk factors (the presence of certain genes associated with Parkinson’s disease) are more commonly seen in early-onset Parkinson’s.

Age

Gender

Pesticide Exposure

Exposure to some pesticides has been shown to raise the risk of developing Parkinson’s.

Fungicide and Herbicide Exposure

Exposure to the fungicide maneb or the herbicides 2,4-dichlorophenoxyacetic acid (2,4-D), paraquat, or Agent Orange may raise the risk of Parkinson’s.

Head Injuries

Coffee and Smoking

How Is Parkinson’s Disease Diagnosed?

There aren’t any specific tests to diagnose someone with Parkinson’s disease.

Doctors typically make a diagnosis based on the following:

• Medical history
• A neurological exam
• Blood and lab tests (to rule out other disorders)
• Brain scans (to rule out other disorders)

Prognosis of Parkinson’s Disease

As Parkinson’s progresses, symptoms often worsen. While some people can respond well to therapy and have minimal disability issues, others can be more seriously affected over time, regardless of measures taken to slow the onset.

Although Parkinson’s isn’t considered a fatal disease itself, it can cause life-threatening complications that may shorten a person’s lifespan.

Duration of Parkinson’s Disease

Treatment and Medication Options for Parkinson’s Disease

For decades, doctors couldn’t treat Parkinson’s disease effectively and thought that it was a terminal illness. In the late 19th century, arsenic, morphine, hemlock, and cannabis were used to treat tremors.

By the 1940s and 1950s, neurosurgeons had begun to perform surgery on the basal ganglia of the brain, which resulted in improvements in Parkinson’s disease symptoms. While this surgery was sometimes effective, it was also risky — about 10 percent of patients died as a result of the operation.

Medication Options

Medications for Parkinson’s disease fall into three general categories:

• Medications that increase the level of the neurotransmitter dopamine in your brain
• Medications that affect other neurotransmitters, to help control motor symptoms
• Medications to help control nonmotor symptoms

Treating Parkinson’s disease with medication can be a balancing act between managing the disease and managing drug side effects.

Surgical Options

Deep brain stimulation surgery is an option for people with Parkinson’s disease whose symptoms are disabling despite best medication therapy. This is effective at treating severe tremors that impact a person’s ability to function or symptoms that fluctuate throughout the day in response to medication.

With this method, doctors implant electrodes in specific areas of the brain. The electrodes connect to a generator that’s implanted in the patient’s chest. The generator sends electrical pulses to the brain, which help reduce symptoms. By adjusting these electrical pulses, patients can often reduce their medication burden by up to 50 percent. Most people continue to take some dopamine-based medication even after surgery.

Another surgical option is MRI-guided focused ultrasound, which uses targeted ultrasound therapy to disrupt the brain network causing tremors. This can be very effective for people with bothersome tremor that may not be able to tolerate a more invasive procedure like deep brain stimulation.

Alternative and Complementary Therapies

Some people with Parkinson’s disease use complementary therapies to manage their symptoms.

These approaches may include:

• Exercise Staying physically active can improve flexibility, strength, and mobility.
• Diet A healthy diet can promote overall health for people with Parkinson’s disease.
• Massage A massage may help lessen muscle tension and make you more relaxed.
• Tai Chi This ancient type of Chinese exercise can improve balance, strength, and flexibility.
• Yoga Yoga involves stretching and poses that can help with flexibility and balance.
• Meditation Some people report that meditation can reduce pain and stress.
• Feldenkrais Method These movement lessons have been shown to reduce depression and improve quality of life.

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• Alexander Technique This method focuses on muscle posture and balance.
• Boxing Instructors at the nonprofit organization Rock Steady Boxing teach boxing exercises to help improve agility, muscular endurance, and hand-eye coordination among people with Parkinson’s. Find a class in your area.

Prevention of Parkinson’s Disease

Researchers don’t know of any proven ways to prevent Parkinson’s disease, but avoiding certain risk factors and adopting a healthy lifestyle may reduce your risk.

Researchers have studied various formulations of nicotine — including intranasal, transdermal, and chewing gum — to see whether they could help with Parkinson’s symptoms, but so far none has been found effective at slowing the progression of Parkinson’s.

African Americans and Parkinson’s Disease

A study published in 2021 showed that Black people with Parkinson’s were, on average, four years older at the time they received their diagnosis than white people with this condition.

The study also revealed racial disparities when it comes to diagnosis, treatment, survival, and medication use that negatively impact Black people compared with white people who have Parkinson’s.

For example, Black people were more likely to receive care for Parkinson’s through the emergency department than white people and were less likely to be taking medications for parkinsonism and mood disorders than white people.

Related Conditions and Causes of Parkinson’s Disease

Many conditions can cause symptoms that are similar to those of Parkinson’s disease, including the following:

• Essential tremor
• Normal pressure hydrocephalus
• Dementia with Lewy bodies
• Multiple system atrophy
• Progressive supranuclear palsy
• Corticobasal degeneration

The Takeaway

• Parkinson’s disease causes symptoms such as tremors, muscle stiffness, slow movement, and balance issues that typically worsen over time.
• Symptoms and progression can vary widely depending on the subtype of Parkinson’s disease.
• Most cases are idiopathic, meaning the exact cause is unknown, though genetics and environmental factors are believed to play a role.
• There is no proven way to prevent Parkinson’s disease, but a healthy lifestyle may help reduce risk.