Parkinson’s disease (PD) is a neurodegenerative disease associated with low dopamine production by neurons. The exact cause of PD is still being researched by medical science. Current research being conducted includes understanding the interactions between neurons and glial cells in the brain. This interaction may be the key to understanding PD and one day finding a cure.
Definitions & Facts
Parkinson’s disease (PD) is a disorder of the nervous system that affects the patient’s motor function. It is a chronic and progressive neurodegenerative disorder that begins slowly and worsens as it progresses. It affects nearly one million people in the United States.
The first descriptive writings about the symptoms of PD date back to the ancient Egyptians. In 1817, James Parkinson published an essay called, “An Essay on the Shaking Palsy”. His essay renewed interest in the disease with the medical community of the 18th century, and the disorder was subsequently renamed in his honor. Parkinson’s typically affects older adults.
Symptoms & Complaints
The secondary symptoms include anxiety, depression, dementia, pain, incontinence, and sleep disturbance. Secondary symptoms may or may not be related to low dopamine production. Initially, tremors may begin slowly in the arms and hands, and ultimately lead to more debilitating symptoms.
In the 1950’s, Parkinson’s disease was first associated with dopamine deficiency. Dopamine is a neurotransmitter that is produced by neurons. Neurotransmitters are chemicals in the brain that send messages from the brain to various parts of the body. Different neurotransmitters send different messages and instructions to the body.
Dopamine instructs the muscles of the body to perform normal coordinated movements. When dopamine is absent, the hallmark signs of PD become apparent, such as tremors, slow movement, and impaired balance. It is not clear why the neurons stop producing dopamine, but as the production of dopamine decreases, the symptoms of PD increase and worsen.
The gradual decrease in dopamine production explains why PD is a progressive degenerative neurological condition, but it does not explain why the production of dopamine decreases as we age. Medical scientists are currently studying the root cause of why neurons quit producing neurotransmitters. Their research may one day explain the cause of numerous degenerative diseases that are related to the normal aging process. There are other non-dopamine related symptoms associated with PD, and may include different neurotransmitters.
Medical research has also identified the appearance of Lewy bodies in the brains of people with PD and other neurodegenerative diseases. Lewy bodies are clumps of abnormal proteins that should have been cleaned up by the neuron’s natural cleansing process. This cleansing process involves close interaction between neuron cells and glial cells in the brain. The role of glial cells is beginning to merit deeper medical research in the cause PD.
External causes that increase the risk of PD may include toxins or other environmental factors, but this has not been substantiated. Genetics may also play a role in PD, but again, the occurrence of genetically-related PD is small.
Diagnosis & Tests
There are currently no specific tests specific to confirm Parkinson’s disease. The attending physician may diagnose PD based on external symptoms, medical history of the patient, neurological and physical examinations. Tests such as MRIs, ultrasound, SPECT and PET scan may be ordered to help rule out other diseases or disorders. These test will not diagnose PD, but they will rule out other possible causes of the symptoms that are specific to PD.
It may take time and through the process of elimination, to diagnose a patient with PD. Specific medications may be prescribed in small quantities that may relieve the symptoms of PD. A diagnosis of PD may be offered by the physician when all other causes of symptoms are ruled out, and if medication helps to alleviate symptoms.
Treatment & Therapy
At present, Parkinsons’s disease cannot be cured. Medication is used to manage symptoms that are associated with low dopamine production. The most common medication prescribed for PD is carbidopa-levodopa. This is a natural chemical that is able to pass into the brain and then converts to dopamine. The newest medication to be approved by the U.S. Food and Drug Administration is called Duopa™. This particular medication is administered through a feeding tube which helps to maintain continuous infusion of the medication.
Dopamine agonists may also be used to decrease the symptoms of PD. These medications do not actually convert into dopamine like levodopa, but rather mimic dopamine. They may be used in conjunction with levodopa. Another medication used includes MAO-B inhibitors that help prevent the breakdown of dopamine in the brain. These should not be used with levodopa, as they may cause hallucinations in patients. Anticholinergics help control tremors, and amantadine may provide short-term relief of early onset symptoms.
Deep brain stimulation (DBS) is also used; although complications with DBS make this option less viable, it may be beneficial for patients with advanced PD. All of these medications and DBS only help to alleviate symptoms of PD. There is currently no known cure for Parkinson’s disease.
Prevention & Prophylaxis
Observational research has found that caffeine may help to reduce the risk of developing PD. Some researchers also suggest aerobic exercise may help to reduce PD from developing. There are numerous articles written that discuss lifestyle approaches that may slow down neurodegenerative diseases such as exercise, proper nutrition, and exercises for the brain. None of these are substantiated, but they are still healthy lifestyle choices overall.