Parkinson's disease is a chronic neurological condition that causes a wide variety of symptoms and makes movement difficult. It affects each person differently and progresses at a different rate. Treatment requires a multidisciplinary approach that involves exercise, physical and speech therapy, medications and even surgery in some cases. Since there is no cure, treatments are aimed at maintaining independence and controlling symptoms, which includes taking medications that stimulate dopamine production.
Considerations
In order for movement to occur, the brain must send signals through the nervous system to the part of the body that needs to move. The nerves that travel through the body are not all connected, but are separated by spaces called synaptic gaps. These gaps allow the body to have a check and balance system to decide if a nerve impulse should go through.
If a signal is to go through, chemicals called neurotransmitters help the nerve signal cross the gap, states the University of Washington. One of these neurotransmitters is dopamine, which is produced by a structure in the brain called the substantia nigra. If there is not enough dopamine available, movement can be affected.
Identification
For reasons that are not completely understood, in some patients the body attacks and destroys the cells of the substantia nigra, which in turn decreases the amount of dopamine that is available. According to the National Parkinson Foundation, by the time symptoms are severe enough to cause concern, 60 percent to 80 percent of the dopamine-producing cells already are damaged.
While each case is different, warning symptoms include shaking or tremors in the hands, legs or other areas, slowness of movement, stiffness in the arms, legs or trunk and difficulty maintaining balance. More subtle signs include small, cramped handwriting and speech that becomes softer and harder for others to hear.
Benefits
The goal of treatment is to minimize symptoms and reduce disability as much as possible. Part of the plan might involve taking medications that stimulate the production of dopamine. Levodopa is a common choice, as this chemical can be used by the brain to make dopamine, according to the National Institute of Neurological Disorders and Stroke.
Levodopa is often combined with carbidopa, which prevents levodopa from being converted into dopamine in the bloodstream, allowing more of it to get to the brain. The challenge is that not all patients respond to this medication the same way and it usually needs to be combined with other medications to fully control symptoms.
Concerns
While levodopa and carbidopa can reduce symptoms in some patients, these medications can cause problems as well. Side effects can include nausea, vomiting, fatigue, a drop in blood pressure, confusion, dry mouth and dizziness. However, the biggest challenge is that over time the body adapts to the medication so that more is needed to create the same effect. As the dosage increases, it can cause spontaneous, involuntary movements, tremors and other symptoms similar to those that it is supposed to be treating, warns the Parkinson's Disease Foundation. In other words, there is a limit to how much levodopa and carbidopa a patient can take before the side effects become too severe. Given this, there are many other medications to control symptoms that are often combined with levodopa and carbidopa, so that less levodopa and carbidopa is needed.
Effectiveness
Levodopa and carbidopa also relieve symptoms temporarily. This is referred to as having "on" and "off" periods. When the medication is working, symptoms might disappear or be minimal, then within hours of taking the medication, it wears off and symptoms reappear.
The Medline Plus website recommends timing the medication so that "on" periods happen when a patient needs to be active and that a patient rests when "off" periods occur. It also is important to consult with a registered dietitian, as some foods such as high amounts of protein can interfere with the absorption of this medication, so meals need to be timed as well.
References
- University of Washington: Neurotransmitters and Neuroactive Peptides
- National Parkinson Foundation: What is Parkinson's Disease
- National Institute of Neurological Disorders and Stroke: Parkinson's Disease Information Page
- Parkinson's Disease Foundation: Prescription Medications
- Medline Plus: Levodopa and Carbidopa
