Parkinson's disease

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What is Parkinson's Disease?

Parkinson's disease is a slowly progressive, neurodegenerative disease generally associated with tremor or trembling of the arms and legs, stiffness and rigidity of the muscles, and slowness of movement. The cause is still unknown, although medical experts believe the symptoms are related to a chemical imbalance in the brain. This chemical imbalance is caused by brain cell death.

An estimated 1 million people in the United States have Parkinson's disease. It affects both men and women, generally 40 years of age or older.

Symptoms

Symptoms vary from patient to patient. Symptoms appear slowly and in no particular order. Many years may pass before early symptoms progress to the point where they interfere with normal activities. The four major hallmark symptoms of Parkinson's disease are:

Rigidity -- stiffness when the arm, leg or neck is moved back and forth

Resting Tremor -- tremor most prominent at rest, when sitting quietly

Bradykinesia -- slowness in initiating movement

Loss of postural reflexes -- patients have poor balance and may fall

Cause

A small area in the brain called the substantia nigra produces a chemical called dopamine. Dopamine, once it is produced, travels through the cell to its end terminal in another portion of the brain called the striatum.

In Parkinson's disease, the cells in the substantia nigra begin to die. As they die, less dopamine is made so that less is transported to the striatum. Since the striatum is a coordination center for the various chemicals, when there is not enough dopamine, there is a chemical imbalance. This chemical imbalance leads to the symptoms of Parkinson's disease. Later in the disease, cells in other portions of the brain and nervous system also degenerate.

Treatment

Current therapy consists primarily of dopamine replacement. This is accomplished by using levodopa and other dopamine-enhancing agents. These drugs are helpful for the majority of Parkinson's patients in both improving disability and reducing mortality.

Pallidotomy and Thalamotomy are treatments in which a surgical lesion is made in a portion of the brain called the pallidum (globus pallidus) or the thalamus. This treatment has been shown to reduce symptoms in some patients.

Neuropathology

PD is characterized by specific brain lesions found in substantia nigra and other subcortical nuclei, namely Lewy bodies, made up of aggregates of alpha-synuclein.

Experimental treatments

Deep brain stimulation is an experimental method of treating Parkinson's disease. In this treatment, electrodes are placed in a part of the brain called the thalamus and a pacemaker is used to stimulate the thalamus.

There is also significant research showing that fetal tissue transplants survive and replace the brain cells that have died as a result of Parkinson's disease.

There are a multitude of exciting new drugs expected to be on the market soon for the treatment of Parkinson' s disease. These include dopamine agonists, COMT inhibitors and growth factors.