Health TopicsParkinson's disease

Parkinson's disease

Parkinson’s disease is a common neurodegenerative disorder. Learn more about Parkinson's disease causes, risk factors, and how to treat and manage symptoms.


An estimated 90,000 people over age 65 are diagnosed with Parkinson’s disease every year in the United States, according to the Parkinson’s Foundation. This condition affects the brain and can cause symptoms like tremors (involuntary shaking), stiffness, and poor balance that develop slowly and worsen gradually. Scientists have yet to find a cure for the condition, but treatment can help manage symptoms.

Learn more about Parkinson’s disease, its symptoms, why it occurs, and what treatment options are available to improve quality of life for people with this condition.

What is Parkinson's disease?

Mature man sits in his living room, head in hand looking worried about his Parkinson's diagnosis

The National Institutes of Health estimates that upwards of one million people in the U.S. are living with Parkinson’s disease, making it the second-most common neurodegenerative disorder behind Alzheimer’s disease. A neurodegenerative disorder occurs when cells in the nervous system (the brain, spinal cord, and the body’s network of nerves) die or stop working properly. This results in a steady decline in physical and cognitive abilities, which include higher-level brain functions such as thinking, reasoning, remembering, and learning.

Parkinson’s disease can affect people in different ways and progress at varying rates, but many with the condition will eventually experience tremors, trouble walking, muscle stiffness, and poor balance.

Around 8.5 million people worldwide live with Parkinson’s disease, and numbers appear to be on the rise. Disability and death due to Parkinson’s are increasing faster than disability and death due to any other nervous system disorder, according to the World Health Organization.

Most people who are diagnosed with Parkinson’s disease are older than 60, but between 5 and 20 percent of people are diagnosed at ages younger than 50. This is known as early-onset Parkinson’s disease (formerly known as young-onset Parkinson’s disease).

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What are the signs and symptoms of Parkinson's disease?

The symptoms of Parkinson’s disease vary from person to person. In general, they tend to develop slowly and worsen gradually over time. Symptoms may begin on one side of the body or in one limb then spread to other areas of the body as the disease progresses.

Movement-related symptoms

The four main symptoms of Parkinson’s disease impact a person’s ability to move. These include:

Tremors: Tremors related to Parkinson’s usually have a rhythmic, back-and-forth motion and often begin in the jaw or a hand or foot. Often, tremors will go away or improve during sleep or when intentionally moving. This symptom occurs in around 80 percent of people with Parkinson’s disease.  

Bradykinesia: This refers to a slowing down of movement that can make everyday tasks more difficult and time-consuming. While there’s no actual loss of muscle strength, many people have trouble controlling their movements and promptly completing actions like washing dishes or buttoning a shirt. Bradykinesia sometimes causes a decrease in facial expressions that can result in what’s known as a “masked face.” Typically, the identification of bradykinesia is required for a Parkinson’s disease diagnosis. 

Muscle stiffness: Many people with Parkinson’s disease experience prolonged periods of muscle stiffness. Constant, unrelenting stiffness—known as “lead-pipe rigidity”—can coincide with short, jerky movements called “cogwheel stiffness.” This describes lead-pipe rigidity that occurs alongside tremors. 

Unstable posture: As the Parkinson’s disease progresses, changes in posture and impaired balance can occur. Someone with the condition may lean forward or hunch over and take short, shuffled steps while keeping their arms still. This is sometimes called “parkinsonian gait.”

Other possible movement-related symptoms of Parkinson’s disease include: 

  • Changes in handwriting (known as micrographia) 
  • Difficulty swallowing (dysphagia) 
  • A softer-than-normal speaking voice (hypophonia)
  • Reduced blinking
  • Drooling due to loss of facial muscle control

Non-movement symptoms

Parkinson’s disease can affect more than your ability to move. Many people with the condition also experience:

  • Emotional changes: Degenerative conditions like Parkinson’s disease can sometimes lead to a loss of motivation and symptoms of depression. In other cases, people may become increasingly irritable, fearful, or pessimistic. 
  • Cognitive issues: Because Parkinson’s disease affects the brain, issues like mild cognitive impairment (noticeable changes in memory or behavior that aren’t severe enough to disrupt daily life) can occur. As the disease progresses, some people may develop dementia (known as Parkinson’s disease dementia).
  • Bladder or bowel problems: Nervous system problems related to Parkinson’s disease may result in constipation or bladder issues, including urinary hesitancy (difficulty starting and maintaining urine stream), urinary urgency (a compelling need to urinate), or urinary incontinence (loss of bladder control, often causing urine leakage). 
  • Orthostatic hypertension: Orthostatic hypertension refers to a sudden drop in blood pressure when standing up, which can cause dizziness, lightheadedness, or fainting.  
  • Changes in skin: Skin may become very oily, especially around the nose and forehead, and dandruff may occur. In other cases, people experience excessive sweating or skin dryness.   
  • Poor sleep: Many people with Parkinson’s disease experience insomnia (trouble falling or staying asleep). Some people experience frequent nightmares, restless legs syndrome, or rapid eye movement (REM) behavior disorder—a condition that causes a person to act out their dreams while sleeping. In other cases, excessive daytime sleepiness or sudden onset of sleep may occur.
  • Loss of smell: A person’s sense of smell may be completely lost (a condition called anosmia) or reduced (hyposmia), although this may go unnoticed for years. The loss of smell may be an early sign of Parkinson’s disease.

Parkinson’s disease pain

It’s common for people to experience pain as Parkinson’s disease progresses. Pain associated with Parkinson’s can be divided into five main categories:

  • Musculoskeletal pain: This deals with the bones, muscles, and joints. Musculoskeletal pain from Parkinson’s may feel constant or it may come and go.
  • Neuropathic pain: This comes from nerve damage. Parkinson’s-related damage can occur in any part of a nerve, from where it branches out from the spinal cord to its endings in the skin. 
  • Dystonic pain: This is pain that results from repeated muscle spasms, twisting, and cramps from Parkinson’s.  
  • Akathisia: This refers to feelings of restlessness or an inability to sit still. Akathisia is relatively common among people with Parkinson’s.
  • Central pain: When pathways in the brain, brainstem, or spinal cord that control pain and sensation don’t work properly, central pain can occur. Central pain is often characterized by sensations of tingling or burning. Some people may feel like there’s something crawling on or under their skin.

It’s important to remember that these aren’t all the possible symptoms of Parkinson’s disease. Neurodegenerative disorders like Parkinson’s are complex conditions that affect people differently and can cause a diverse range of symptoms.  

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When should you see a healthcare provider?

Closeup of a senior man with Parkinson's disease holding the hand of his nurse

You should speak with a healthcare provider (HCP) if you notice any possible warning signs of Parkinson’s disease. While your symptoms may be related to another condition, it’s still important to receive a timely diagnosis and appropriate treatment as soon as possible.

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What causes Parkinson's disease?

Some of the most noticeable Parkinson’s disease symptoms occur when nerve cells in the basal ganglia (the part of the brain that manages movement) stop working properly or die. Healthy nerve cells produce dopamine, a brain chemical that facilitates movement and emotions like motivation, arousal, and reward. They also produce norepinephrine, a chemical messenger that helps regulate blood pressure and heart rate. In a person with Parkinson’s disease, less dopamine and norepinephrine are generated and brain activity becomes abnormal. Researchers aren’t sure what causes nerve cells to die or stop working.   

Additionally, people with Parkinson’s disease have brain cells that contain Lewy bodies, which are abnormal clumps of a protein called alpha-synuclein that can’t be broken down according to the brain’s routine process. Lewy bodies and the presence of alpha-synuclein are currently a key focus of Parkinson’s disease research.

While the exact cause of Parkinson’s disease is still unclear, it’s widely believed that a complex interaction of genetic and environmental factors contributes to the condition.


Genetics are responsible for around 10 to 15 percent of Parkinson’s disease cases, according to the Parkinson’s Foundation. Researchers have identified certain genetic changes (known as mutations) associated with Parkinson’s disease that can be passed from parent to child. Even so, someone with one of these genetic mutations still has a relatively small chance of developing the condition.

The genetic mutations linked to Parkinson’s disease appear to occur more commonly in certain ethnic groups, including Ashkenazi Jews and North African Arab Berbers. The reasons for this are unknown. 

Environmental factors

Around 90 percent of Parkinson’s disease cases are not genetic, meaning environmental factors may play a role in some diagnoses. Researchers have identified a handful of environmental factors that could contribute to Parkinson’s disease, although the reasons why are largely unclear. More research on these possible links is ongoing:

Head injuries: Experiencing traumatic brain injuries (TBIs) is associated with an increased risk of developing Parkinson’s disease. TBIs are caused by violent blows to the head, such as those that may happen during a contact sport or vehicle accident.

Herbicides and pesticides: Studies show a connection between Parkinson’s disease and exposure to some herbicides and pesticides. One notable herbicide is paraquat, which is widely used in the U.S. but banned in 32 countries, including China and the European Union. More Parkinson’s-specific research is needed to fully understand any link between the condition and these substances. 

Polychlorinated biphenyls (PCBs): PCBs are a group of man-made organic chemicals used to produce commercial and industrial products like electrical equipment, paints, and dyes. The U.S. banned the manufacturing of PCBs in 1979 due to their toxicity, although PCBs that are inadvertently generated in select concentrations and under certain conditions are still permitted. Relatively large concentrations of PCBs have been found in the brains of people who had Parkinson’s disease.

Solvents: Trichloroethylene (an industrial solvent) is associated with Parkinson’s disease in workers whose jobs resulted in prolonged exposure. Trichloroethylene is also the most common organic contaminant found in groundwater.  

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What are the risk factors for Parkinson's disease?

A risk factor is any characteristic or behavior that increases a person’s likelihood of developing a certain condition. Risk factors for Parkinson’s disease include: 

  • Age: Most cases of Parkinson’s disease are diagnosed in people older than 60. In fact, around one percent of people in this age group have Parkinson’s. 
  • Assigned sex at birth: Parkinson’s disease is more common in people assigned male at birth than in people assigned female at birth.

As mentioned above, certain genetic and environmental factors may also influence one’s risk of developing Parkinson’s disease:

  • Family history: Having a close blood relative with Parkinson’s disease puts you at a slightly elevated risk for the condition. If you have multiple blood relatives with Parkinson’s, your risk is higher.
  • Exposure to toxins: Prolonged exposure to certain pesticides, herbicides, solvents, and PCBs can increase your risk of Parkinson’s disease. 
  • Head injuries: Repeated head injuries can damage the brain and raise your Parkinson’s disease risk. 

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How is Parkinson's disease diagnosed?

Most cases of Parkinson’s disease are diagnosed after an HCP evaluates a person’s medical and family histories and performs a thorough neurological exam. Your HCP may refer you to a doctor called a neurologist who specializes in evaluating and treating nervous system disorders. 

There’s currently no specific test that can diagnose Parkinson’s disease. Certain blood tests and imaging methods, such as a computed tomography (CT) scan or magnetic resonance imaging (MRI) of the brain, may be used to help rule out or support a Parkinson’s diagnosis in some cases. An HCP may also prescribe a Parkinson’s disease medication called levodopa and confirm a diagnosis if the person’s symptoms clearly improve.

If a person’s symptoms are mild or difficult to diagnose, an HCP may recommend a dopamine transporter scan (DaTscan). This imaging test is performed using a single-photon emission computed tomography (SPECT) scanner that helps create a picture of the brain’s dopamine system. While a DaTscan can’t definitively diagnose Parkinson’s disease, it can help rule out conditions that cause similar symptoms, such as essential tremor. 

Meanwhile, there may be a promising new test for Parkinson’s disease on the horizon. In 2023, the Parkinson Progression Marker Initiative study evaluated the spinal fluid of more than 1,100 participants. It used a test called an alpha-synuclein seed amplification assay to screen for clumps of alpha-synuclein protein (a key indicator of Parkinson’s).

Study participants included people with Parkinson’s, people without the condition, and individuals who were considered to have a high risk of developing it. The test accurately identified people with Parkinson’s in nearly 88 percent of cases and showed notable sensitivity to the at-risk participants, meaning early detection of and intervention for Parkinson’s disease may soon be achievable.  

Another emerging diagnostic method for Parkinson’s disease is a skin test that involves taking small samples of surface nerve tissue. The skin samples are collected from spots on the legs and back, then analyzed to determine if alpha-synuclein proteins display a certain type of function that could indicate an increased risk of Parkinson’s disease. More research on this method is necessary before it’s made widely available.  

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What are the stages of Parkinson's disease?

Because Parkinson’s disease can cause a diverse range of symptoms and progresses at varying rates, staging the condition in a conventional way isn’t particularly helpful. Instead, the Movement Disorder Society-Unified Parkinson’s Disease Rating Scale (MDS-UPDRS) is often used to evaluate severity of the condition.

The MDS-UPDRS is a comprehensive, 50-question assessment of Parkinson’s disease symptoms that’s divided into four parts:

  • Part 1: Non-movement aspects of experiences of daily living: This covers Parkinson’s disease symptoms that aren’t related to movement, such as depression, dementia, and constipation.
  • Part 2: Movement aspects of experiences of daily living: This deals with how movement-related symptoms of Parkinson’s disease affect the person’s ability to perform everyday tasks, such as getting dressed and bathing.
  • Part 3: Movement examination: The criteria in this section measure the effects of movement-related symptoms based on speaking abilities, walking speed and posture, facial expressions, balance, and other factors. 
  • Part 4: Movement complications: In this section, an HCP determines how big of an impact movement-related Parkinson’s symptoms have on a person’s everyday life. This includes evaluating the number, severity, and duration of symptoms the person experiences each day. 

Evaluating the impact of Parkinson’s disease symptoms on an individual basis can help HCPs provide more personalized treatment plans and improve quality of life for patients.

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How is Parkinson's disease treated?

Closeup of a woman's hands pouring a bottle of medication for Parkinson's disease treatment

No two cases of Parkinson’s disease are exactly alike, so treatment will vary from person to person. In general, though, Parkinson’s disease treatment focuses on improving symptoms and slowing the progression of the condition through medication, rehabilitation, surgery, or a combination of these approaches.

Medications for Parkinson’s disease

Many medications for Parkinson’s disease work by raising dopamine levels in the brain or affecting other brain chemicals. The best type and dosage of medication for you will depend on your symptoms, overall health, and how long you’ve had the condition. Commonly prescribed Parkinson’s disease medications include:

Levodopa: The most effective treatment for Parkinson’s disease symptoms, levodopa is a natural chemical in the body that’s used by nerve cells to raise dopamine levels. Because medicinal levodopa alone can cause nausea and vomiting, it’s almost always combined with a drug called carbidopa that helps minimize side effects. Some HCPs refer to this combination as carbidopa-levodopa.  

Carbidopa-levodopa is available in tablet, capsule, and inhalable powder form, as well as a gel form that can be fed directly into the small intestine through a feeding tube.  

Catechol-O-methyltransferase (COMT) inhibitors: This drug can help extend the effects of levodopa. A body enzyme called catechol-O-methyltransferase can break down levodopa before it reaches the brain, so COMT inhibitors such as entacapone and opicapone may be prescribed to prevent this from happening.

Dopamine agonists: These drugs mimic the effects of dopamine in the brain, essentially leading the brain to feel as if it’s getting the dopamine it needs to function well. Dopamine agonists are available in tablet form (pramipexole), as a patch (rotigotine), and in shot form (apomorphine).

Monoamine oxidase-B (MAO-B) inhibitors: This medication helps stop a brain enzyme called monoamine oxidase-B from breaking down dwindling dopamine levels in the brain. There are several MAO-B inhibitors available in capsule or tablet form, including selegiline, rasagiline, and safinamide.

Amantadine: Often prescribed to provide short-term relief from mild Parkinson’s symptoms, amantadine can also help control dyskinesia, involuntary movements that may be a side effect of levodopa. It’s available in capsule, tablet, and liquid forms. 

Adenosine receptor antagonists (A2A receptor antagonists): These drugs focus on receptors in the brain that help control the response to dopamine. A2A receptor antagonists are available in tablet form (known as istradefylline).

Several other medications can be recommended to help improve specific symptoms of Parkinson’s disease, such as sleeping issues and constipation.

Taking any medication comes with some measure of risk, including drugs used to treat Parkinson’s disease. Possible side effects of Parkinson’s disease medications include, but aren’t limited to:

  • Nausea and vomiting
  • Dyskinesia (involuntary movements) 
  • Lightheadedness when standing
  • Hallucinations (seeing, hearing, or feeling things that aren’t real)
  • Sleepiness and fatigue
  • Insomnia
  • Headaches
  • Diarrhea


Rehabilitation methods like physical, occupational, and speech therapies can help improve movement-related symptoms, slow disease progression, and enhance daily function for people living with Parkinson’s disease.

Physical therapy (PT):  Physical therapy for Parkinson’s disease may involve balance and gait training, strategic exercises, and resistance training to keep you moving well for as long as possible. PT can help you deal with the physical challenges a Parkinson’s diagnosis might bring. For example, you may learn fall prevention tips and exercise guidelines that are tailored to your specific needs.  

Occupational therapy (OT): Occupational therapy for Parkinson’s disease teaches strategies that can help you perform daily tasks and continue to participate in activities you enjoy. Your OT sessions will be individualized to your needs and goals. For instance, you might receive hand coordination training to help you make the small movements required to perform tasks such as cooking, buttoning shirts, painting, and gardening. 

Speech therapy (ST): Speech changes occur in up to 89 percent of people with Parkinson’s disease. ST performed by a speech-language pathologist can improve your ability to communicate, stay connected with loved ones, and manage swallowing difficulties. Promptly starting an ST program after noticing speech or swallowing changes may help you preserve speaking abilities as the disease progresses. 

The Parkinson’s Foundation recommends beginning a rehabilitation program at diagnosis. Your HCP can provide individualized guidance about what types of therapies may be best for you. 


Parkinson’s disease drugs tend to become less effective as the condition progresses. In some cases, surgical treatments can be used to help control symptoms when medications stop working. 

Deep brain stimulation (DBS): DBS is the main type of surgery for Parkinson’s disease. During the procedure, electrodes are implanted in a specific part of the brain. These implants are connected to a small generator that’s inserted in the chest around the collarbone. Powered by the generator, the electrodes painlessly stimulate parts of the brain that facilitate movement. Although the ways in which DBS works aren’t fully understood, many experts believe it helps regulate electrical signaling patterns in the brain. DBS may be appropriate for some people who experience tremors, rigidity, and slow movement.

Focused ultrasound therapy (FUS): FUS is a noninvasive surgical treatment for Parkinson’s disease-related tremors, stiffness, slowness, and dyskinesia. The patient is fully awake during the procedure, during which ultrasound beams are precisely aimed at certain parts of the brain with the assistance of MRI technology. The goal of surgery is to destroy brain cells in small portions of the brain that are associated with certain symptoms. For example, the procedure may target a part of the thalamus (located near the center of the brain) to address tremors.

A large body of current medical research is focused on improving Parkinson’s disease treatment options. Promising new methods such as stem cell treatments, nerve cell repair methods, and gene therapies are on the horizon, although more research is necessary before these treatments become widely available.

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What are the possible complications of Parkinson's disease?

Just as the symptoms of Parkinson’s disease vary, so can its complications. Perhaps the most well-known Parkinson’s complication is Parkinson’s disease dementia (PDD), which may occur as the disease becomes advanced. An estimated 70 percent of people with Parkinson’s disease eventually develop dementia. Most research shows the average time from the onset of movement symptoms to the development of dementia is around 10 years.

PDD refers to a decline in thinking and behavior in a person who has already been diagnosed with Parkinson’s disease. A similar condition called Lewy body dementia occurs when changes in thinking and behavior occur before movement-related Parkinson’s disease symptoms.

Someone with PDD may have difficulty:

  • Solving problems
  • Communicating with others
  • Remembering things
  • Paying attention
  • Understanding abstract concepts 
  • Making sound judgments 

Other possible symptoms of PDD include increased irritability and aggressiveness, sometimes accompanied by hallucinations and delusions (experiencing strange beliefs or paranoid thinking).

Both Parkinson’s disease and PDD result from degenerating nerve cells. PDD can’t be reversed, but treatment can help slow the progression of symptoms. People live an average of five to seven years after a PDD diagnosis, according to research, but life expectancy depends on the individual case.

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Can you prevent Parkinson's disease?

There’s no reliable way to prevent Parkinson’s disease, although researchers have identified a few factors that appear to lower the risk of the condition. These include:

  • Exercise: Getting regular moderate to vigorous exercise early in life is associated with a lower risk of Parkinson’s disease in older adults.
  • Caffeine consumption: Drinking caffeinated beverages like coffee or tea may have a protective effect against Parkinson’s disease.
  • Certain medications: Research shows that using statins (medications prescribed to lower cholesterol levels) or regularly taking anti-inflammatory drugs like ibuprofen may reduce the risk of Parkinson’s disease. (Always speak with your HCP before changing or starting any new medication.) 
  • Vitamin D: While more research on this subject is needed, there may be a link between higher vitamin D levels and a lower risk of Parkinson’s disease.

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What is the outlook for Parkinson's disease?

Most people with Parkinson’s will eventually need assistance from a caregiver, as the disease gets progressively worse. Still, disease progression is often very slow, and advances in treatment allow many people with the condition to remain independent for years.

In 1967, the average life expectancy after a Parkinson’s disease diagnosis was just under 10 years. Today, the average life expectancy is more than 14.5 years. And because Parkinson’s disease is usually diagnosed after age 60, many people with the condition generally live as long as those without it.

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Living with Parkinson's disease

Senior woman with Parkinson's walking arm-in-arm with her friend in a park as they smile and talk

Parkinson’s disease affects people in different ways, so everyone’s experience is unique. Performing everyday tasks and socializing with others may become more difficult as Parkinson’s progresses. This can lead to feelings of frustration or hopelessness, sometimes along with depression or anxiety that necessitates treatment.

Many people with Parkinson’s disease find it helpful to speak with licensed mental health providers or to connect with individuals who face similar challenges in online or in-person support groups. This might also be helpful for people who feel stressed, overwhelmed, and burned out from caring for a loved one with the disease.

Simply sharing your feelings with loved ones can also help you cope. Just remember, you’re not alone in your Parkinson’s disease journey.

In addition to following your HCP’s treatment guidance, making healthy lifestyle choices might help you better manage your symptoms and continue to enjoy your favorite activities. You may find it beneficial to:

  • Exercise regularly (to the best of your ability) to improve strength, coordination, and balance.
  • Eat a varied, nutrient-rich diet to support your overall health.
  • Try yoga or tai-chi, which can promote mental wellness and enhance flexibility.
  • Treat yourself to tension-relieving massage therapy.
  • Incorporate relaxation techniques into your daily routine, such as meditation, prayer, or deep-breathing exercises.

Your care team is an invaluable resource if you’re living with Parkinson’s disease. Depending on how your symptoms evolve, your HCP can adjust your treatment plan or refer you to additional professionals who can help. This might include an occupational therapist, massage therapist, or clinical social worker who can assist you in planning for the future. With the right treatment and support, you can live better with Parkinson’s disease.  

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Featured Parkinson's disease articles

Topic page sources
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Cleveland Clinic. Parkinson’s Disease. Last reviewed April 15, 2022. 

Gonzalez-Usigli H. Parkinson Disease (PD). Merck Manual Consumer Version. Last updated September 2022.

International Parkinson and Movement Disorder Society. Results from the PPMI Study on An Alpha-Synuclein Seed Amplification Assay. Accessed July 17, 2023.

Mayo Clinic. Parkinson’s Disease. Last reviewed May 26, 2023. 

National Cancer Institute. Neurodegenerative Disorder. Accessed July 13, 2023.

National Institute on Aging. Parkinson’s Disease: Causes, Symptoms, and Treatments. Last reviewed April 14, 2022. 

National Institute of Neurological Disorders and Stroke. Parkinson’s Disease. Last reviewed March 8, 2023.

National Institute of Neurological Disorders and Stroke. Parkinson’s Disease: Challenges, Progress, and Promise. Last reviewed January 30, 2023.

Ou Z, Pan J, Tang S, et al. Global Trends in the Incidence, Prevalence, and Years Lived With Disability of Parkinson's Disease in 204 Countries/Territories From 1990 to 2019. Front Public Health. 2021;9:776847. Published 2021 Dec 7.

Parkinson’s Foundation. Causes. Accessed July 13, 2023.   

Parkinson’s Foundation. Dementia. Accessed July 18, 2023.

Parkinson’s Foundation. Environmental Factors. Accessed July 17, 2023.

Parkinson’s Foundation. Genetics & Parkinson’s. Accessed July 17, 2023. 

Parkinson’s Foundation. Getting Diagnosed. Accessed July 17, 2023.

Parkinson’s Foundation. Loss of Smell. Accessed July 20, 2023.

Parkinson’s Foundation. Notable Figures with Parkinson’s. Accessed July 12, 2023.    

Parkinson’s Foundation. Pain. Accessed July 21, 2023.

Parkinson’s Foundation. Physical, Occupational & Speech Therapies. Accessed July 18, 2023.

Parkinson’s Foundation. Prescription Medications. Accessed July 18, 2023.

Parkinson’s Foundation. Prevalence & Incidence. Accessed July 13, 2023. 

Parkinson’s UK. MDS Unified Parkinson’s Disease Rating Scale (MDS-UPDRS). Last reviewed November 24, 2022.   

Siderowf A, Concha-Marambio L, Lafontant D-E, Farris CM, Ma Y, Urenia PA, et al. Assessment of heterogeneity among participants in the Parkinson's Progression Markers Initiative cohort using α-synuclein seed amplification: A cross-sectional study. May 2023.

The Michael J. Fox Foundation for Parkinson’s Research. Deep Brain Stimulation. Accessed July 18, 2023. 

The Michael J. Fox Foundation for Parkinson’s Research. Focused Ultrasound. Accessed July 18, 2023. 

UCSF Weill Institute for Neurosciences. Parkinson’s Disease Dementia. Accessed July 18, 2023.

United States Environmental Protection Agency. Learn About Polychlorinated Biphenyls. Last updated April 12, 2023.  

Vila-Chã N, Cavaco S, Mendes A, et al. Central Pain in Parkinson's Disease: Behavioral and Cognitive Characteristics. Parkinsons Dis. 2021;2021:5553460. Published 2021 Jun 10.

World Health Organization. Parkinson’s Disease. Last updated June 13, 2022.

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