Parkinson's disease is a neurological disorder that becomes progressively worse over time as the neurons in the substantia nigra area of the brain degenerate. This can greatly affect people's ability to move and induce symptoms commonly associated with Parkinson's disease, such as rigidity, tremors and other uncontrollable movements. Though dopamine can help slow the progression of Parkinson's disease, oral supplementation will have no effect.
Effect of Dopamine
Dopamine can have a beneficial effect on Parkinson's disease by improving the signaling capabilities of the neurons. In their 2002 article "The Roles of Dopamine," Salk Institute for Biological Studies professors Jean-Marc Fellous and Roland E. Suri say dopamine in the brain helps to regulate neuron firing rates by controlling the proportion of calcium, potassium and sodium in a cell. Through this mechanism, certain types of dopamine therapy can help control movement problems associated with Parkinson' disease.
Blood-Brain Barrier
The problem with oral dopamine supplementation is that dopamine cannot cross the blood-brain barrier. According to Georgia Health Sciences University experts, any amount of oral dopamine is unhelpful for Parkinson's disease. The most common and effective solution to this problem is the prescription of oral levodopa. Levodopa is a naturally occurring substance in the human body that crosses the blood-brain barrier easily and subsequently converts into dopamine.
Dopamine Agonists
Though oral dopamine cannot aid in Parkinson's disease treatment, synthetic dopamine agonists have been shown to be effective. Dopamine agonists like pramipexole and ropinirole pass through the blood-brain barrier, but each type of drug may act differently from other dopamine agonists. University of California experts note that each person also react differently to dopamine agonists. People may need to try multiple medications before finding the agonist that works best for them. Unlike levodopa, dopamine agonists often cause negative side effects like dry mouth, nausea, dizziness and leg swelling.
Degradation of Effectiveness
As Parkinson's disease progresses, medications that provide dopamine to the brain become less effective. Doctors may prescribe other medications to prevent the breakdown of dopamine or levodopa as a way of improving dopamine medication. People who do not respond to levodopa or whose Parkinson's disease is advanced enough may need brain surgery, which carries significant risks and may worsen dementia.
References
- "The Handbook of Brain Theory and Neural Networks"; The Roles of Dopamine; Jean-Marc Fellous and Roland E. Suri; 2002
- Georgia Health Sciences University: Parkinson's Disease Possible Treatment Options
- University of Maryland Medical Center; Facts About Parkinson's Disease; September 2010
- University of California San Francisco: Dopamine Agonists
