Health

Synonyms
paralysis agitans, shaking palsy

Definitions

Parkinson’s disease (PD)
Parkinson’s disease is a neurodegenerative disease that causes an overall slowness and difficulty with moving. There are cells in the brain in an area called the substantia nigra that produce a neurotransmitter called dopamine. Dopamine is needed to produce smooth, fluid movement. When the brain is deficient in dopamine, it causes the major symptoms of Parkinson’s disease, including tremor (shaking), bradykinesia (slow movement), rigidity (stiffness), and postural instability. English physician James Parkinson first described this condition in 1817.

Young-onset PD
Young-onset PD is similar to Parkinson’s disease but occurs on or before the age of 40 and is more likely to cause cramping, aching, and posturing and less likely to be associated with dementia.

Related conditions

Parkinsonism
Parkinsonism is a clinical condition similar to but distinct from Parkinson’s disease that is caused by secondary identifiable problems like toxins or medications that mimic the symptoms of Parkinson’s disease.

Essential tremor
Essential tremor is a common disorder that causes tremor or shaking of the hands and sometimes involves the head. This condition commonly affects both hands at the onset and does not usually cause significant disability. It does not respond well to the medications used to treat Parkinson’s disease. Progressive supranuclear palsy
Progressive supranuclear palsy (PSP) shares similar symptoms with Parkinson’s disease but has some notable differences like high risk for falls early on in the disease process, symptoms tend to progress faster, and both sides of the body are affected from the onset. Other symptoms include fainting spells and difficulty moving their eyes.

Multiple system atrophy
Multiple system atrophy (MSA) has similar symptoms to Parkinson’s disease but usually does not include tremor, may progress faster, has more problems with incontinence and sudden drops in blood pressure (orthostatic hypotension), as well as fluctuation between too high and too low blood pressure.

Corticobasilar degeneration
Corticobasilar degeneration is a rare condition that causes symptoms like PSP but can be unilateral (affecting only one side of the body) and eye movement may not be affected.

Dementia with Lewy bodies
Dementia with Lewy bodies (DLB) causes Parkinsonism (Parkinson-like symptoms) and dementia. It shares features of Alzheimer’s disease. It is caused by abnormal protein deposits in the brain called Lewy bodies.

Statistics
It is estimated that as many as 1.5 million people are living with Parkinson’s disease. There are about 60,000 new cases of Parkinson’s disease diagnosed each year. This number probably does not reflect the true number of cases, however, because it is thought that some cases go undiagnosed. The chance of developing Parkinson’s disease increases with advancing age. About 15% of Parkinson’s disease cases are diagnosed under the age of 50.

Anatomy
The basal ganglia is a deep brain structure that controls the smooth, coordinated movement of our bodies and specific movements. Chemical signals called neurotransmitters connect the brain cell by sending chemical signals along complex neural pathways.

The Problem
Parkinson’s disease is caused by a loss of a group of dopamine-producing neurons in the substantia nigra. The substantia nigra is located in a structure deep in the brain called the basal ganglia. These neurons die out over time, producing the clinical symptoms of Parkinson’s disease by causing an imbalance in the neurotransmitters in the brain. This part of the brain controls movement initiation and coordination.

Risk factors

Genetics
There is no clear genetic cause for Parkinson’s disease in the vast majority of cases. There are a small number of families in which genes have been identified and this is contributing to the understanding of all forms of Parkinson’s disease.

Ethnicity
There is not a higher incidence in any specific ethnic group. Asians seem to have a lower risk.

Age
Advanced age is associated with increasing incidence of Parkinson’s disease. The incidence (number of new cases) increases significantly after the age of 85.

Gender
Parkinson’s disease is more common in men than women.
  
Exposure to pesticide or herbicide
There is a slightly higher risk of Parkinson’s disease with exposure to pesticides or herbicides. Decreased estrogen
Women who are post menopausal or who have had hysterectomies may be at higher risk. Studies of post-menopausal women on hormone replacement seem to show a lower risk.

Geography
There is a higher risk for people who live in rural areas on farms or those who drink well water.

Cost
It is estimated that the direct and indirect cost of Parkinson’s disease is nearly $25 million per year in the United States. This includes cost of diagnosing and treating the disease along with loss of work and disability payments. Medication cost can average about $2,500 per year and surgeries can cost $10,000 to $100,000.