What is Parkinson disease?
Parkinson disease (or Parkinson) is the most common form of Parkinsonism, a group of motor system disorders. It is a disease that slowly gets worse over time. It is caused by the loss of brain cells that make dopamine. Dopamine is a substance that helps with smooth and coordinated muscle movement. Parkinson often has these symptoms:
- Tremor or trembling of the arms, jaw, legs, and face
- Stiffness or rigidity of the limbs and trunk
- Slowness of movement (bradykinesia)
- Problems with balance and coordination
What causes Parkinson disease?
The cause of Parkinson is unknown. Experts believe the symptoms are linked to a chemical imbalance in the brain caused by brain-cell death. Parkinson is chronic. Symptoms grow worse over time.
This disease may appear in younger people (even teenagers). But it often affects people in late middle age. It is not contagious.
Experts think that in most people the cause of Parkinson is a mix of genetics and environmental exposure. Studies have shown that rural living, exposure to well water, and exposure to agricultural pesticides and herbicides are linked to Parkinson. But these factors do not guarantee you will get the disease. Nor does their absence prevent it.
In the other forms of Parkinsonism, either the cause is known or suspected. Or the disorder occurs as a secondary effect of some other neurological problem. These forms are sometimes called Parkinson syndrome, atypical Parkinson, or, simply, Parkinsonism. They may be caused by:
- Tumors in the brain
- Repeated head trauma, such as from boxing
- Long-time use of certain medicines, such as phenothiazines, butyrophenones, or reserpine for mental health problems, and metoclopramide for stomach upset
- Toxins, such as manganese and carbon monoxide poisoning
- Postencephalitic Parkinsonism, a viral disease that causes “sleeping sickness”
- Striatonigral degeneration, a disease that affects the part of the brain called the substantia nigra
Parkinsonism may also occur with other nervous system problems. These include:
- Shy-Drager syndrome
- Progressive supranuclear palsy
- Wilson disease
- Huntington disease
- Hallervorden-Spatz syndrome
- Alzheimer disease
- Creutzfeldt-Jakon disease
- Olivopontocerebellar atrophy
- Post-traumatic encephalopathy
- Dementia with Lewy bodies
Who is at risk for Parkinson disease?
The biggest risk factor for Parkinson is advancing age. The average age for Parkinson symptoms to start is 60 years. Men are affected more than women. But the reason for this is unclear.
Family history is another key risk factor. A person with an affected parent or sibling has a 4% to 9% higher chance of getting Parkinson. This higher risk is most likely because of a mix of environmental and genetic factors. Having 1 or more close relatives with Parkinson raises the risk of the disease. But unless the person has a known genetic change (mutation) for Parkinson, the increased risk is 2% to 5%.
What are the symptoms of Parkinson disease?
These are the most common symptoms of Parkinson:
- Rigid muscles. Stiffness when the arm, leg, or neck is moved back and forth.
- Resting tremor. Tremor (involuntary movement from contracting muscles) that is most obvious at rest.
- Bradykinesia. Slowness in starting movement.
- Postural instability. Poor posture and balance that may cause falls or gait problems.
Symptoms of Parkinson vary from person to person. The symptoms may appear slowly and in no certain order. Early symptoms may be subtle. They may slowly get worse over many years before reaching a point where they mess with normal daily activities.
Other symptoms are divided into motor (movement-related) and non-motor symptoms.
- Slow movement (bradykinesia)
- Rigidity and freezing in place
- Stooped posture
- Shuffling gait
- Decreased arm swing when walking
- Trouble getting up from a chair
- Small, cramped handwriting (micrographia)
- Lack of facial expression
- Slowed activities of daily living (for example, eating, dressing, and bathing)
- Trouble turning in bed
- Staying in a certain position for a long period of time
- Diminished sense of smell
- Low voice volume (hypophonia)
- Trouble speaking (dysarthria)
- Painful foot cramps
- Sleep problems
- Emotional changes (fearful and insecure)
- Skin problems
- Increased sweating
- Urinary frequency or urgency
- Male erectile dysfunction
As the disease gets worse, walking may become affected. It may cause the person to stop in mid-stride or “freeze” in place, and maybe even fall over. People also may start walking with a series of quick, small steps as if hurrying forward to keep balance. This is known as festination.
The symptoms of Parkinson may look like other health problems. Always see your healthcare provider for a diagnosis.
How is Parkinson disease diagnosed?
Diagnosing Parkinson in the early stages can be hard. At first, signs and symptoms may look like other health problems or the effects of normal aging. For this reason, your healthcare provider may want to watch your symptoms for some time until they are consistently there.
Right now, there are no blood or lab tests to diagnose Parkinson. Diagnosis of Parkinson is based mainly on a health history and nervous system exam. Brain scans or lab tests may be done to help rule out other diseases or conditions. But brain scans generally will turn out to be normal with Parkinson.
You may need:
- Neurological exam. This includes looking at symptoms and how serious they are.
- Trial test of medicines. When symptoms are severe, a trial test of medicines (mainly levodopa or L-dopa) may be used. If symptoms are eased from the use of levodopa, this suggests Parkinson.
- CT scan. An imaging test that uses X-rays and a computer to make images ) of the body, including the bones, muscles, fat, and organs. CT scans are more detailed than general X-rays.
- MRI. A test that uses large magnets, radio waves, and a computer to make detailed images of organs and structures within the body.