Parkinson's Disease

  • Medical Author:

    Sietske N. Heyn is a medical writer with a PhD in neuroscience. Dr. Heyn's education includes a BS with honors from the University of Oregon, and a doctoral degree in neuroscience from the University of California at Davis. After completing postdoctoral training at the University of California, San Francisco, and many years of working as a medical writer at the Stanford University Center for Down Syndrome Research, Dr. Heyn now runs her own medical writing business.

  • Medical Editor: Melissa Conrad Stöppler, MD
    Melissa Conrad Stöppler, MD

    Melissa Conrad Stöppler, MD

    Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.

View Parkinson's Disease Slideshow Pictures

Parkinson's disease facts

  • Parkinson's disease is a neurodegenerative disorder which leads to progressive deterioration of motor function due to loss of dopamine-producing brain cells.
  • Primary symptoms include
    • tremor,
    • stiffness,
    • slowness,
    • impaired balance,
    • and later on a shuffling gait.
  • Some secondary symptoms include
  • Most individuals with Parkinson's disease are diagnosed when they are 60 years old or older, but early-onset Parkinson's disease also occurs.
  • With proper treatment, most individuals with Parkinson's disease can lead long, productive lives for many years after diagnosis.

What is Parkinson's disease?

Parkinson's disease is the second most common neurodegenerative disorder and the most common movement disorder. It is characterized by progressive loss of muscle control, which leads to trembling of the limbs and head while at rest, stiffness, slowness, and impaired balance. As symptoms worsen, it may become difficult to walk, talk, and complete simple tasks.

The progression of Parkinson's disease and the degree of impairment vary from individual to individual. Many people with Parkinson's disease live long productive lives, whereas others become disabled much more quickly. Premature death is usually due to complications such as falling-related injuries or pneumonia.

Most individuals who develop Parkinson's disease are 60 years of age or older. Since overall life expectancy is rising, the number of individuals with Parkinson's disease will increase in the future. Adult-onset Parkinson's disease is most common, but early-onset Parkinson's disease (onset between 21-40 years), and juvenile-onset Parkinson's disease (onset before age 21) also exist.

Descriptions of Parkinson's disease date back as far as 5000 BC. Around that time, an ancient Indian civilization called the disorder Kampavata and treated it with the seeds of a plant containing therapeutic levels of what is today known as levodopa. Parkinson's disease was named after the British doctor James Parkinson, who in 1817 first described the disorder in great detail as "shaking palsy."

What causes Parkinson's disease?

A substance called dopamine acts as a messenger between two brain areas - the substantia nigra and the corpus striatum - to produce smooth, controlled movements. Most of the movement-related symptoms of Parkinson's disease are caused by a lack of dopamine due to the loss of dopamine-producing cells in the substantia nigra. When the amount of dopamine is too low, communication between the substantia nigra and corpus striatum becomes ineffective, and movement becomes impaired; the greater the loss of dopamine, the worse the movement-related symptoms. Other cells in the brain also degenerate to some degree and may contribute to non-movement related symptoms of Parkinson's disease.

Although it is well known that lack of dopamine causes the motor symptoms of Parkinson's disease, it is not clear why the dopamine-producing brain cells deteriorate. Genetic and pathological studies have revealed that various dysfunctional cellular processes, inflammation, and stress can all contribute to cell damage. In addition, abnormal clumps called Lewy bodies, which contain the protein alpha-synuclein, are found in many brain cells of individuals with Parkinson's disease. The function of these clumps in regards to Parkinson's disease is not understood. In general, scientists suspect that dopamine loss is due to a combination of genetic and environmental factors.

What genes are linked to Parkinson's disease?

In most individuals, Parkinson's disease is idiopathic, which means that it arises sporadically with no known cause. However, some of individuals diagnosed with Parkinsons also have family members with the disease. By studying families with hereditary Parkinson's disease, scientists have identified several genes that are associated with the disorder. Studying these genes helps understand the cause of Parkinson's disease and may lead to new therapies. So far, five genes have been identified that are definitively associated with Parkinson's disease.

  1. SNCA (synuclein, alpha non A4 component of amyloid precursor): SNCA makes the protein alpha-synuclein. In brain cells of individuals with Parkinson's disease, this protein aggregates in clumps called Lewy bodies. Mutations in the SNCA gene are found in early-onset Parkinson's disease.
  2. PARK2 (Parkinson's disease autosomal recessive, juvenile 2): The PARK2 gene makes the protein parkin. Mutations of the PARK2 gene are mostly found in individuals with juvenile Parkinson's disease. Parkin normally helps cells break down and recycle proteins.
  3. PARK7 (Parkinson's disease autosomal recessive, early onset 7): PARK7 mutations are found in early-onset Parkinson's disease. The PARK7 gene makes the DJ-1 protein, which may protect cells from oxidative stress.
  4. PINK1 (PTEN-induced putative kinase 1): Mutations of this gene are found in early-onset Parkinson's disease. The exact function of the protein made by PINK1 is not known, but it may protect structures within the cell called mitochondria from stress.
  5. LRRK2 (leucine-rich repeat kinase 2): LRRK2 makes the protein dardarin. Mutations in the LRRK2 gene have been linked to late-onset Parkinson's disease.

Several other chromosome regions and the genes GBA (glucosidase beta acid), SNCAIP (synuclein alpha interacting protein), and UCHL1 (ubiquitin carboxyl-terminal esterase L1) may also be linked to Parkinson's disease.

Who is at risk for Parkinson's disease?

  • Age is the largest risk factor for the development and progression of Parkinson's disease. Most people who develop Parkinson's disease are older than 60 years years of age.
  • Men are affected about 1.5 to 2 times more often than women.
  • A small number of individuals are at increased risk because of a family history of the disorder.
  • Head trauma, illness, or exposure to environmental toxins such as pesticides and herbicides may be a risk factor.

Quick GuideParkinson's Disease: Symptoms, Causes, Stages, Treatment

Parkinson's Disease: Symptoms, Causes, Stages, Treatment
Caring for people with Parkinson's disease

Parkinson's Disease Diet and Nutrition

Maintaining Your Weight With Parkinson's Disease

Malnutrition and weight maintenance is often an issue for people with Parkinson's disease. Here are some tips to help you maintain a healthy weight.

  • Weigh yourself once or twice a week, unless your doctor recommends weighing yourself often. If you are taking diuretics or steroids, such as prednisone, you should weigh yourself daily.
  • If you have an unexplained weight gain or loss (2 pounds in one day or 5 pounds in one week), contact your doctor. He or she may want to modify your food or fluid intake to help manage your condition.
  • Avoid low-fat or low-calorie products. (unless other dietary guidelines have been recommended). Use whole milk, whole milk cheese, and yogurt.

What are the symptoms of Parkinson's disease?

The primary symptoms of Parkinson's disease are all related to voluntary and involuntary motor function and usually start on one side of the body. Symptoms are mild at first and will progress over time. Some individuals are more affected than others. Studies have shown that by the time that primary symptoms appear, individuals with Parkinson's disease will have lost 60% to 80% or more of the dopamine-producing cells in the brain. Characteristic motor symptoms include the following:

  • Tremors: Trembling in fingers, hands, arms, feet, legs, jaw, or head.Tremors most often occur while the individual is resting, but not while involved in a task. Tremors may worsen when an individual is excited, tired, or stressed.
  • Rigidity: Stiffness of the limbs and trunk, which may increase during movement. Rigidity may produce muscle aches and pain. Loss of fine hand movements can lead to cramped handwriting (micrographia) and may make eating difficult.
  • Bradykinesia: Slowness of voluntary movement. Over time, it may become difficult to initiate movement and to complete movement. Bradykinesia together with stiffness can also affect the facial muscles and result in an expressionless, "mask-like" appearance.
  • Postural instability: Impaired or lost reflexes can make it difficult to adjust posture to maintain balance. Postural instability may lead to falls.
  • Parkinsonian gait: Individuals with more progressive Parkinson's disease develop a distinctive shuffling walk with a stooped position and a diminished or absent arm swing. It may become difficult to start walking and to make turns. Individuals may freeze in mid-stride and appear to fall forward while walking.

Secondary symptoms of Parkinson's disease

While the main symptoms of Parkinson's disease are movement-related, progressive loss of muscle control and continued damage to the brain can lead to secondary symptoms. These vary in severity, and not every individual will experience all of them. Some of the secondary symptoms include:

What other conditions resemble Parkinson's disease?

In its early stages, Parkinson's disease can resemble a number of other conditions with Parkinson-like symptoms known as Parkinsonism. These conditions include multiple system atrophy, progressive supranuclear palsy, corticobasal degeneration, Lewy body dementia, stroke, encephalitis (inflammation of the brain), and head trauma. Alzheimer's disease and primary lateral sclerosis can also be mistaken for Parkinson's disease. Other similar conditions include essential tremor, dystonic tremor, vascular Parkinsonism, and drug-induced Parkinsonism.

How is Parkinson's disease diagnosed?

An early and accurate diagnosis of Parkinson's disease is important in developing good treatment strategies to maintain a high quality of life for as long as possible. However, there is no test to diagnose Parkinson's disease with certainty (except after the individual has passed away). A diagnosis of Parkinson's disease - especially in the early phase - can be challenging due to similarities to related movement disorders and other conditions with Parkinson-like symptoms. Individuals may sometimes be misdiagnosed as having another disorder, and sometimes individuals with Parkinson-like symptoms may be inaccurately diagnosed as having Parkinson's disease. It is therefore important to re-evaluate individuals in the early phase on a regular basis to rule out other conditions that may be responsible for the symptoms.

A neurologist who specializes in movement disorders will be able to make the most accurate diagnosis. An initial assessment is made based on medical history, a neurological exam, and the symptoms present. For the medical history, it is important to know whether other family members have Parkinson's disease, what types of medication have been or are being taken, and whether there was exposure to toxins or repeated head trauma in the past. A neurological exam may include an evaluation of coordination, walking, and fine motor tasks involving the hands.

Several guidelines have been published to assist in the diagnosis of Parkinson's disease. These include the Hoehn and Yahr scale and the Unified Parkinson's Disease Rating Scale. Tests are used to measure mental capacity, behavior, mood, daily living activities, and motor function. They can be very helpful in the initial diagnosis, to rule out other disorders, as well as in monitoring the progression of the disease to make therapeutic adjustments. Brain scans and other laboratory tests are also sometimes carried out, mostly to detect other disorders resembling Parkinson's disease.

The diagnosis of Parkinson's disease is more likely if:

  1. at least two of the three major symptoms are present (tremor at rest, muscle rigidity, and slowness);
  2. the onset of symptoms started on one side of the body;
  3. symptoms are not due to secondary causes such as medication or strokes in the area controlling movement; and
  4. symptoms are significantly improved with levodopa (see below).

What is the treatment for Parkinson's disease?

There is currently no treatment to cure Parkinson's disease. Several therapies are available to delay the onset of motor symptoms and to ameliorate motor symptoms. All of these therapies are designed to increase the amount of dopamine in the brain either by replacing dopamine, mimicking dopamine, or prolonging the effect of dopamine by inhibiting its breakdown. Studies have shown that early therapy in the non-motor stage can delay the onset of motor symptoms, thereby extending quality of life.

The most effective therapy for Parkinson's disease is levodopa (Sinemet), which is converted to dopamine in the brain. However, because long-term treatment with levodopa can lead to unpleasant side effects (a shortened response to each dose, painful cramps, and involuntary movements), its use is often delayed until motor impairment is more severe. Levodopa is frequently prescribed together with carbidopa (Sinemet), which prevents levodopa from being broken down before it reaches the brain. Co-treatment with carbidopa allows for a lower levodopa dose, thereby reducing side effects.

In earlier stages of Parkinson's disease, substances that mimic the action of dopamine (dopamine agonists), and substances that reduce the breakdown of dopamine (monoamine oxidase type B (MAO-B) inhibitors) can be very efficacious in relieving motor symptoms. Unpleasant side effects of these preparations are quite common, including swelling caused by fluid accumulation in body tissues, drowsiness, constipation, dizziness, hallucinations, and nausea.

For some individuals with advanced, virtually unmanageable motor symptoms, surgery may be an option. In deep brain stimulation (DBS), the surgeon implants electrodes to stimulate areas of the brain involved in movement. In another type of surgery, specific areas in the brain that cause Parkinson's symptoms are destroyed.

An alternative approach that has been explored is the use of dopamine-producing cells derived from stem cells. While stem cell therapy has great potential, more research is required before such cells can become of therapeutic value in the treatment of Parkinson's disease.

In addition to medication and surgery, general lifestyle changes (rest and exercise), physical therapy, occupational therapy, and speech therapy may be beneficial.

How can people learn to cope with Parkinson's disease?

Although Parkinson's disease progresses slowly, it will eventually affect every aspect of life - from social engagements, work, to basic routines. Accepting the gradual loss of independence can be difficult. Being well informed about the disease can reduce anxiety about what lies ahead. Many support groups offer valuable information for individuals with Parkinson's disease and their families on how to cope with the disorder. Local groups can provide emotional support as well as advice on where to find experienced doctors, therapists, and related information. It is also very important to stay in close contact with health care professionals to monitor the progression of the disease and to adjust therapies to maintain the highest quality of living.

Can Parkinson's disease be prevented?

Scientists currently believe that Parkinson's disease is triggered through a complex combination of genetic susceptibility and exposure to environmental factors such as toxins, illness, and trauma. Since the exact causes are not known, Parkinson's disease is at present not preventable.

What is the prognosis of Parkinson's disease?

The severity of Parkinson's disease symptoms vary greatly from individual to individual and it is not possible to predict how quickly the disorder will progress. Parkinson's disease itself is not a fatal disease, and the average life expectancy is similar to that of people without the disease. Secondary complications, such as pneumonia, falling-related injuries, and choking can lead to death. There are many treatment options that can reduce some of the symptoms and can prolong the quality of life of an individual with Parkinson's disease.

Medically reviewed by Joseph Carcione, DO; American board of Psychiatry and Neurology

REFERENCES:

Arenas, E. Towards stem cell replacement therapies for Parkinson's disease. Biochemical and Biophysical Research Communications, 2010; vol 396: pp 152-156.

Chen, J.C. Parkinson's Disease: Health-Related Quality of Life, Economic Cost, and Implications of Early Treatment American Journal of Managing Care, 2010; vol 16: pp S87-S93.

Fricker-Gates, R.A. and Gates, M.A. Stem cell-derived dopamine neurons for repair in Parkinson's disease. Regenerative Medicine, March 2010; vol 5(2): pp267-78.

Hauser, R.A., Early Pharmacologic Treatment in Parkinson's Disease. American Journal of Managing Care, 2010; vol 16: pp S100-S107.

Pahwa, R. and Lyons, K.E. diagnosis of Parkinson's disease: recommendations from diagnostic clinical guidelines. American Journal of Managing Care, 2010; vol 16: pp S194-S99.

Quick GuideParkinson's Disease: Symptoms, Causes, Stages, Treatment

Parkinson's Disease: Symptoms, Causes, Stages, Treatment

Subscribe to MedicineNet's General Health Newsletter

By clicking Submit, I agree to the MedicineNet's Terms & Conditions & Privacy Policy and understand that I may opt out of MedicineNet's subscriptions at any time.

Reviewed on 8/9/2016
References
Medically reviewed by Joseph Carcione, DO; American board of Psychiatry and Neurology

REFERENCES:

Arenas, E. Towards stem cell replacement therapies for Parkinson's disease. Biochemical and Biophysical Research Communications, 2010; vol 396: pp 152-156.

Chen, J.C. Parkinson's Disease: Health-Related Quality of Life, Economic Cost, and Implications of Early Treatment American Journal of Managing Care, 2010; vol 16: pp S87-S93.

Fricker-Gates, R.A. and Gates, M.A. Stem cell-derived dopamine neurons for repair in Parkinson's disease. Regenerative Medicine, March 2010; vol 5(2): pp267-78.

Hauser, R.A., Early Pharmacologic Treatment in Parkinson's Disease. American Journal of Managing Care, 2010; vol 16: pp S100-S107.

Pahwa, R. and Lyons, K.E. diagnosis of Parkinson's disease: recommendations from diagnostic clinical guidelines. American Journal of Managing Care, 2010; vol 16: pp S194-S99.

Health Solutions From Our Sponsors