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Parkinson's
What Is Parkinson's Disease?
Parkinson’s disease (PD) occurs when brain cells that make dopamine, a chemical that coordinates movement, stop working or die. Because PD can cause tremor, slowness, stiffness, and walking and balance problems, it is called a “movement disorder.” But constipation, depression, memory problems and other non-movement symptoms also can be part of Parkinson’s. PD is a lifelong and progressive disease, which means that symptoms slowly worsen over time.
The experience of living with Parkinson’s over the course of a lifetime is unique to each person. As symptoms and progression vary from person to person, neither you nor your doctor can predict which symptoms you will get, when you will get them or how severe they will be. Even though broad paths of similarity are observed among individuals with PD as the disease progresses, there is no guarantee you will experience what you see in others.
Estimates suggest that Parkinson’s affects nearly 1 million people in the United States and more than 6 million people worldwide.
What Is Parkinson's Disease?
What Causes Parkinson's Disease?
Researchers believe that in most people, Parkinson’s is caused by a combination of environmental and genetic factors. Certain environmental exposures, such as pesticides and head injury, are associated with an increased risk of PD. Still, most people have no clear exposure that doctors can point to as a straightforward cause. The same goes for genetics. Certain genetic mutations are linked to an increased risk of PD. But in the vast majority of people, Parkinson’s is not directly related to a single genetic mutation. Learning more about the genetics of Parkinson’s is one of our best chances to understand more about the disease and discover how to slow or stop its progression.
Aging is the greatest risk factor for Parkinson’s, and the average age at diagnosis is 60. Still, some people get PD at 40 or younger.
Men are diagnosed with Parkinson’s at a higher rate than women and whites more than other races. Researchers are studying these disparities to understand more about the disease and health care access and to improve inclusivity across care and research.
How Is Parkinson’s Diagnosed?
Doctors diagnose Parkinson’s “clinically” — the diagnosis is based on a person’s medical history, answers to certain questions and a physical examination.
Any clinical diagnosis rests heavily on the physician’s expertise and judgment. If you suspect you have Parkinson’s, you should see a movement disorder specialist, who is a neurologist with specialized training in Parkinson’s and other movement disorders. On examination, the doctor looks for slowness, stiffness and resting tremor — the movement symptoms of Parkinson’s. (Read more about symptoms.) Being treated by a movement disorder specialist remains critically important as the disease progresses.
Doctors may order tests to exclude other conditions that can look like Parkinson’s. DaT scan is a brain imaging test that captures detailed pictures of the dopamine system in the brain. DaT scan can’t diagnose Parkinson’s on its own and not everyone with suspected Parkinson’s needs this test. In some cases, though, such as when it’s difficult to distinguish Parkinson’s tremor from essential tremor (another common movement disorder), this can be a helpful addition.
A biomarker test is now available to diagnose Parkinson’s objectively, based on the presence of a misfolded protein called alpha-synuclein. Called the alpha-synuclein seeding amplification assay, the test can detect the misfolded protein in spinal fluid in people who show clinical symptoms of the disease and also in people who have not yet shown symptoms but are at a high risk of developing PD. Use of the test is mostly limited to clinical trials but may expand once it is optimized for a less invasive fluid, such as blood.
What Are the Symptoms?
The symptoms of Parkinson’s and their degree of severity are different for every person. The three “cardinal” movement, or motor, symptoms are slowness of movement (bradykinesia), stiffness (rigidity) and resting tremor. Not everyone has all three symptoms and not everyone with Parkinson’s has tremor. Some people also have walking problems or difficulty with balance and coordination.
Non-movement, or non-motor, symptoms are sometimes called the “invisible” symptoms of Parkinson’s because you can’t see them from the outside. These symptoms can occur any time, even before movement symptoms or diagnosis, and differ in severity from person to person. They include constipation, depression, memory or sleep problems, and impact the quality of life for people with Parkinson’s and their families.
It’s important to remember that even if you experience symptoms common among people with Parkinson’s, they may be from a completely different condition. Read more about Parkinson’s symptoms or take the Parkinson’s Screening Questionnaire to see if you should speak to your doctor or a movement disorder specialist about PD.
How Is Parkinson’s Treated?
Medications are available to lessen Parkinson’s movement (motor) and non-movement (non-motor) symptoms, making it possible for people to lead fulfilling and productive lives for many years.
There also are surgical interventions, such as deep brain stimulation (DBS) and focused ultrasound (FUS), which may be an option for certain symptoms. While invasive and not for everyone, DBS can be an option in cases where medication side effects or complications, such as dyskinesia, outweigh medication’s benefits.
While there is no cure or therapy to stop or slow the progression of PD, great strides are being made. Therapies to address movement symptoms and expand options for non-movement symptoms also are improving.
You can do much to take control of your journey with Parkinson’s
Will My Children Get Parkinson's?
Not necessarily. While a small percentage of Parkinson’s cases are caused by a single genetic mutation, the large majority are not. Even if you carry a genetic mutation that increases your risk, your child may not inherit it. And most known genetic mutations linked to PD only increase risk; they don’t guarantee a diagnosis.
Parkinson’s and genetics is a complicated and personal topic. Talk to your doctor and consider consulting with a genetic counselor. This expert can explain what we know about Parkinson’s genetics and walk you through what genetic testing can and can’t tell you. If you decide to get genetic testing, a counselor also can interpret your results.
In the last two decades, researchers moved from a predominant belief that Parkinson’s had no genetic connection to finding several genetic links to PD. Investigating these links has transformed our understanding and contributed to the development of new drugs. Genetics will help researchers continue to unlock clues about the disease and how to treat it.
Could It Be Another Disease?
Early in the disease process, it may be difficult to know whether symptoms indicate Parkinson’s or a disease that looks like it. Like PD, many other movement conditions lack objective tests to diagnose them, and a person’s medical history and a doctor’s physical examination are used to make a diagnosis. Some conditions that may be mistaken for Parkinson’s include:
- Essential tremor. This is the most common movement disorder. It involves an involuntary, rhythmic shaking of the hands, head or voice. The tremor is present with activity, such as writing, eating or speaking.
- Atypical parkinsonism. This category of conditions has movement symptoms of Parkinson’s plus additional symptoms not typical of Parkinson’s. Compared to Parkinson’s, the symptoms may progress more quickly and get less benefit from medication. Conditions include Lewy body dementia, multiple system atrophy, corticobasal degeneration and progressive supranuclear palsy.
- Medication-induced parkinsonism. This is when medications, not Parkinson’s disease, cause movement symptoms (tremor, slowness and stiffness). It typically occurs when drugs that block the dopamine system, such as those for schizophrenia or major depression, are taken for long periods. Some anti-nausea medications also can cause drug-induced parkinsonism.
- Normal pressure hydrocephalus (NPH). This condition is caused by an abnormal buildup of cerebrospinal fluid in the brain. Symptoms include walking problems; memory and thinking (cognitive) changes, sometimes severe enough to interfere with daily activities (dementia); and accidental loss of urine (urinary incontinence). Doctors typically can diagnose NPH with a brain scan and lumbar puncture (spinal tap).
How Can I Help Speed a Cure?
Life with Parkinson’s requires adjustment, and it is normal to feel overwhelmed at times. One way to regain a feeling of control is to get involved in the search for a cure by participating in research. Clinical studies are essential to develop ways to diagnose, treat and possibly predict Parkinson’s. Because clinical studies vary, many different type of volunteers are needed. One thing that stays the same, though, is the consistent need for volunteers. Whether you have Parkinson’s, or are touched by the disease in another way, every single person can play a role in the search for a cure.
