Parkinson's disease (PD) is the second-most common neurodegenerative disease after Alzheimer's disease. This article answers seven frequently asked questions about Parkinson’s, including:

• What is Parkinson’s?
• How many people have Parkinson’s?
• What are the initial symptoms of Parkinson’s disease?
• What is the life expectancy of someone diagnosed with Parkinson’s?
• Are some people more susceptible to Parkinson’s disease than others?
• What are the five stages of Parkinson’s disease?
• Where can I get more information about Parkinson’s?

What is Parkinson’s?

Parkinson’s disease (PD) is a neurodegenerative disorder that primarily affects the dopamine-producing (“dopaminergic”) neurons in the brain. Often referred to as a “movement disorder,” PD can cause tremors, slowness, stiffness, walking difficulties, and balance problems. 

Parkinson’s is a lifelong and progressive disease, so symptoms slowly worsen over time. While Parkinson’s itself is not fatal, complications from PD can lower someone’s life expectancy. 

Parkinson’s is different for everyone who experiences it. Some people experience rapid progression of symptoms over a few years, while others stay in the early stages of the disease for decades. People can live independently with early-stage PD, while later-stage PD may require wheelchairs, bed rest, and round-the-clock care. 

How many people have Parkinson’s?

Parkinson’s diagnoses have been increasing in most countries around the world. Experts think this is because life expectancy has increased worldwide. Parkinson’s is associated with old age; only 5-10% of people with PD receive a diagnosis before age 50. 

In the US, Parkinson’s affects around 6 per 1,000 people aged 45 and over. Approximately 500,000 Americans have been diagnosed with PD, but given that many individuals go undiagnosed or are misdiagnosed, some experts estimate that as many as 1 million Americans have PD. These numbers are expected to double by 2040 as the Baby Boomer generation reaches old age.

What are the initial symptoms of Parkinson’s disease?

Symptoms usually develop slowly over years. Because of the diversity of the disease, symptoms progress differently from one person to the next.

By the time PD is diagnosed, the person typically has difficulty with:

• Involuntary shaking
• Bradykinesia, or slowness of movement and reflexes
• Stiffness
• Impaired balance

Other “non-movement” symptoms include:

• Depression
• Cognitive changes
• Sleep disorders
• Constipation 
• Loss of smell

Non-movement symptoms can appear months or years before a PD diagnosis. To learn more about how symptoms progress, see Do I Have Parkinson's Disease? PD Symptoms and Warning Signs.

What is the life expectancy of someone diagnosed with Parkinson’s?

Although the disease is treatable, there is no cure. Current therapies can improve Parkinson's symptoms so that people with this condition can maintain a good quality of life. 

Research funded by organizations like the Parkinson’s Foundation and the Michael J. Fox Foundation for Parkinson’s Research investigates treatments that can slow or reverse the progression of PD.

Parkinson’s disease is not fatal. The life expectancy depends highly on the type of Parkinson's a person has. If PD is not causing issues with brain function, for example, a person can potentially live as long as someone without the disease.

Are some people more susceptible to Parkinson’s disease than others?

No one knows what causes Parkinson's disease, but a combination of genetic and environmental factors is thought to increase your risk of developing PD.

Most people diagnosed with PD are 50 years or older; however, an estimated 5-10% of people with PD are diagnosed before age 50.

The known risk factors for PD include:

• Gender. Men are 1.5 times more likely to have PD than women.
• Age. The risk of PD increases with age.
• Genetics. Some people with PD have an inheritance pattern of altered genes that could increase their risk.
• Environmental causes. There is a link between people with PD and their exposure to chemicals like pesticides, herbicides, and waste product pollution from metal processing.
• Head injury. Repeated head injuries can increase one's risk of developing PD.

What are the five stages of Parkinson’s disease?

There are five stages of Parkinson’s disease.

• In Stage 1, the person has only mild symptoms. Movement symptoms like tremors tend to occur on one side of the body only. 
• In Stage 2, symptoms such as tremors and stiffness begin to worsen and affect both sides of the body. Daily tasks are more difficult and take longer.
• In Stage 3, considered the mid-stage of PD, loss of balance means falls are more common. Symptoms can make daily tasks–like cooking or getting dressed–a challenge.
• In Stage 4, symptoms are fully developed and severely disabling. While some people with later-stage Parkinson’s may still be able to get around with a cane or minor help, someone with Stage 4 PD symptoms is unable to live alone. 
• By Stage 5, PD is debilitating. A person at this stage usually moves only with help or the use of a wheelchair. People with Stage 5 Parkinson’s disease require constant medical supervision.

For more information on the five stages of Parkinson’s disease, see Long-term Care for Parkinson’s Disease (PD): Finances, Treatment, and Your Options.

Where can I find help for Parkinson’s disease?

Your family doctor or primary care physician may be able to connect you to a neurologist who specializes in motor disorders. If you’re not sure where to start, visit the Ability Central nonprofit database to find organizations near you that support people with Parkinson’s. The Service Locator tool allows you to search by specialty, location, and more. 

Where can I get more information about Parkinson’s disease?

Ability Central offers a series of articles to further your knowledge about Parkinson’s. See:

• What You Need to Know About Your Parkinson's Disease Diagnosis
• Long-term Care for Parkinson’s Disease (PD): Finances, Treatment, and Your Options 
• Do I Have Parkinson's Disease? PD Symptoms and Warning Signs