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Parkinson's disease: A puzzle missing pieces |
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It's a disorder known for centuries to rob individuals of control over their muscles. Yet what do doctors really understand about Parkinson's disease - and what can they tell their patients? Truth is, more about its symptoms than about its cause. Imagine losing control of your muscles little by little. Imagine having no power over the way you move because you're losing nerve cells (neurons) in the part of your brain that governs movement. If you have Parkinson's, you don't have to imagine. You know about the primary symptoms - stiffness, shuffling, shaking and stooped posture - of a progressive disorder that typically begins about age 60. But it can develop much earlier, as actor Michael J. Fox, diagnosed with young-onset Parkinson's at 30, demonstrated. Both genders are vulnerable. What you don't know is what causes your condition, since scientists have yet to prove any one theory. They've learned, however, that the loss of certain neurons in an important part of the brain leads to a shortage of dopamine, a brain-signaling "neurotransmitter" chemical necessary for fine-tuned muscle control. Once it's reduced, symptoms start. Medications restore balance Parkinson's may affect you so gradually that you won't need treatment for several years. Instead, you and your doctor will focus on lifestyle changes, such as diet and exercise, to keep your body fit. You also may undergo physical therapy to increase your mobility and strengthen your muscles. As symptoms intensify, however, you will require medication, which must be adjusted periodically. Many drugs can help restore the balance between dopamine and its sister neurotransmitter, acetylcholine. Levodopa, also called L-dopa, has been the standard therapy, restoring normal activity after being converted to dopamine in the brain. But early in treatment it's largely been replaced by other options including dopamine agonists, which mimic the brain chemical rather than converting to it. These newer medications are routinely used when treatment is started, reflecting their ability to delay involuntary movements known as dyskinesias. As powerful as these and other treatments are in improving mobility, reducing tremors and relieving stiffness, they don't cure Parkinson's or even delay its progress. |
What's more, they can produce many side effects - nausea, drowsiness and insomnia, not to mention memory loss, confusion and even hallucinations. Even L-dopa has downsides. Although most patients eventually use the drug, doctors often delay prescribing it because it's known to trigger dyskinesias after years of use. L-dopa is often combined with carbidopa in a single pill (Sinemet). By reducing side effects and prolonging potency, it allows individuals to live relatively normal lives for years. Surgery gives hope If you develop dyskinesias so severe your symptoms can't be treated with drugs alone, you may need surgery to relieve them. Your neurologist may suggest pallidotomy, which improves tremors, rigidity and slowed movements by obliterating a small amount of brain tissue responsible for them. Or you could undergo deep brain stimulation (DBS). It employs electrical impulses to interrupt signals that play a role in tremors and other symptoms. While DBS is more effective than pallidotomy, it carries a higher complication risk. In either case, only about 5% of Parkinson's patients ever undergo a surgical procedure - but 100% of them will be treated with drugs. More options may be on the horizon as scientists explore better drugs and procedures. In the meantime, there are emotional aspects of this disease that merit your attention. Although Parkinson's is a disorder of movement, depression can be the most debilitating feature. So addressing it will be essential in treating the whole you. Richard Robinson is a science writer in Sherborn, Mass. |
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