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Parkinson's Disease Info

Parkinson's Disease Information
Parkinson disease (PD) is common in the general population, and as more and more people live into their eighties, the clinical, economic and emotional impact of this neurodegenerative disease will dramatically increase in magnitude. Although current therapies can alleviate some symptoms in the short term, the disease never remits and symptoms grow worse over time. PD may ultimately be disabling, but since the disease often progresses gradually, most people lead productive lives for many years after diagnosis.

PD generally affects people over the age of 50 years, with only 15% of those affected showing symptoms before the age of 50. It is estimated that more than 1% of 55 year-old individuals are affected and more than 3% of those over 75 years-of-age have the disease. It appears to be more common among men then women; however, this is not known for sure. Current treatment of PD relies on symptom alleviation through drug treatment or surgical intervention. How well an individual responds to drug treatment is also useful in confirming the diagnosis of Parkinson’s disease.

Scientists have been able to identify why people get Parkinson disease – cells in a certain part of the brain, called the substantia nigra, die off. Under normal circumstances, these neuronal cells produce an important brain chemical known as dopamine. When these cells die or are otherwise unable to produce dopamine, symptoms of Parkinson disease begin to appear. Common symptoms include slowness of movement and reflexes (bradykinesia), rigidity in the arms and legs, tremors and difficulty with balancing and walking.

Although we know which cells die off, the precise reason why they die is not always clear. A few families have a mutation in one of the disease causing genes, which would account for why certain families have many affected individuals. A mutation in a single gene is rare cause of PD, however. Other individuals can trace the cause of their disease back to exposure to a specific toxin, but these too are relatively rare. Most cases of PD are idiopathic (i.e. of unknown cause), and are probably due to a complex interaction between environmental factors and susceptibility genes. Learn about the Genetics of PD.

Another cause of Parkinson disease can be acute head trauma. In fact, head trauma is the strongest predictor of PD in several epidemiological studies. This must be put into perspective, however. A common estimate of the number of traumatic brain injuries in the United States is 1.5 million per year, and yet most of these individuals do not develop PD. Furthermore, most individuals with PD have not had a traumatic brain injury. The fact that a head injury is the biggest predictor of PD shows first and foremost, that we do not yet know why most people develop the disease.

A cure has not yet been discovered for Parkinson disease; however, there are a number of effective treatments for the disease. Most of the symptoms associated with PD are due to a lack of dopamine in the brain. Therefore, most of the medications currently used to treat PD either increase dopamine levels or use similar compounds to mimic the effects of dopamine. These types of drugs are often able to alleviate the tremor but not the other symptoms. Some patients consider their tremor to be the most distressing symptom because of its visibility to others, but this symptom rarely leads to serious disability and approximately a quarter of PD patients do not even have this symptom. Bradykinesia and stiffness are often more worrisome as they can lead to falls and subsequent injuries. It should be emphasized that symptoms will vary from patient to patient with both the type and severity of symptoms.

Since PD results from such a complex mixture of genetic and environmental causes, many studies, such as this one, are focused on identifying susceptibility genes and environmental risk factors. During the next several decades, hopefully this research will yield the knowledge necessary to treat and, ideally, prevent the disease.

For more information, see:

The Genetics of Parkinson's Disease
Some basics on genetics and how genetics affect the development of Parkinson's Disease.

Related Links
Other sites with information on Parkinson's Disease.



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