Understanding Parkinson's Disease -- Diagnosis and Treatment
How Is Parkinson's Disease Diagnosed?
Usually, the outward symptoms of Parkinson's are distinctive enough for a doctor to make a diagnosis in the office. There is no blood test or brain scan that confirms the diagnosis. But if you don't respond to the drugs used to treat Parkinson's disease, it’s possible you may have another type of movement disorder that causes the same type of symptoms. Doing additional tests can help your doctor determine if some other problem is causing your parkinsonian symptoms.
What Are the Treatments for Parkinson’s Disease?
Most Parkinson's disease treatments aim to restore the proper balance of the neurotransmitters acetylcholine and dopamine by increasing dopamine levels. Drugs are the standard way of doing this, but many patients, as their disease worsens, may be candidates for implantation of a brain stimulator.
Conventional Medicine for Parkinson's Disease
Symptoms of Parkinson’s disease can often be effectively controlled for years with medication.
Levodopa -- also called L-dopa -- is the drug most often prescribed. The body metabolizes it to produce dopamine. Giving dopamine directly is ineffective, because the brain's natural defense blocks it from being used by the body. To suppress nausea and other possible side effects, levodopa is used in conjunction with a related drug called carbidopa. The combination is commercially known as Sinemet.
Rarely, a patient cannot tolerate carbidopa and will take levodopa alone. If you take only levodopa, it's important not to take it at the same time as food or vitamins containing vitamin B-6, which interferes with its effectiveness.
Most doctors try to postpone starting patients on levodopa as long as possible, because the drug tends to lose effectiveness over time. However, there is some controversy about waiting to begin treatment with levodopa because it can be so beneficial. Researchers have thus investigated ways to offset the loss of effectiveness.
COMT inhibitors such as tolcapone (Tasmar) and entacapone (Comtan) are drugs that are taken with levodopa. They prolong the duration of symptom relief by blocking the action of an enzyme that breaks down levodopa. Tasmar, however, is rarely used, because it can cause liver damage.
Stalevo is a combination tablet that combines carbidopa/levodopa with entacapone. While carbidopa reduces the side effects of levodopa, entacapone extends the time levodopa is active in the brain.
MAO-B inhibitors also block the action of an enzyme that breaks down dopamine. They may be taken alone early in Parkinson's disease or with other drugs as the disease progresses. MAO-B inhibitors include selegiline (Eldepryl) and rasagaline (Azilect). They are usually used alone, because combining them with other drugs can cause unwanted side effects.
Dopamine agonists are dopamine-like drugs that directly imitate dopamine's activity in the brain. Pramipexole (Mirapex), rotigotine (Neuropro), and ropinirole (Requip) used alone or in combination with L-dopa treat the motor symptoms of Parkinson's disease.
Other medications prescribed for Parkinson's disease include apomorphine, benztropine, amantadine, selegiline, and anticholinergic drugs; all can help control various symptoms -- in some cases by releasing dopamine from nerve cells, in others by reducing the effects of acetylcholine, a neurotransmitter that can cause a drop in dopamine.