New treatment guidelines for Parkinson's disease

By Christy Oglesby
CNN

(CNN) -- New recommendations for the treatment of early-stage Parkinson's disease modify a 35-year-old standard and offer improved quality of life for sufferers, researchers say.

For almost four decades, doctors have prescribed levodopa first to help alleviate the muscle stiffness and slowed reaction times caused by Parkinson's. But that drug caused patients to experience uncontrollable, jerky movements, a condition known as dyskinesia.

After reviewing data from several studies, doctors now recommend the use of dopamine agonists, not levodopa, as the first-line treatment. They treat the stiffness caused by the disease while reducing the risk of developing dyskinesia.

"Parkinson's is really two diseases," said William C. Koller, a professor of neurology and one of the authors of the article, which appears in the journal Neurology. "There's the slowness and stiffness that's Parkinson's and there's the dyskinesia that is a complication of long-term levodopa treatment."

Dyskinesia also is a side effect of taking dopamine agonists, Koller said, but it is often delayed and is not as severe as it is with levodopa. Other side effects include nausea, dizziness, headache and sleeplessness.

Prolonged use of levodopa also causes neuropsychiatric complications, and its effects linger indefinitely, regardless of what subsequent treatments doctors might use. As Parkinson's progresses, patients develop other problems such as freezing episodes, falling or dementia that do not respond to levodopa therapy.

The Neurology article revises the previous treatment algorithm, or decision tree, by recommending delayed use of levodopa while starting treatment with drugs that imitate the specific brain chemical that Parkinson's patients lack.

Understanding Parkinson's

Doctor's are not certain what causes Parkinson's disease, a disorder of the central nervous system, but they have located a defective gene in some families that have had a high occurrence of the disorder. Disease symptoms include rigid muscles, slight tremors, poor balance, walking problems and bradykinesia -- extreme slowness of movements and reflexes.

Doctors have determined that Parkinson's is associated with a loss of dopamine, a chemical transmitter in the brain. People with the disease have a shortage of cells that produce dopamine. While levodopa goes to areas of the brain that convert the drug to dopamine, dopamine agonists are drugs that mimic dopamine and do not need the help of converter cells.

Historically, doctors used dopamine agonists as adjuncts for patients already on levodopa who began to experience motor problems. The recommendations in the journal represent a significant shift, said Koller, who is also the director of the movement disorder division at the University of Miami.

Three new dopamine agonists are available for the treatment of Parkinson's -- pramipexole, sold as Mirapex; ropinirole, sold as Requip; and cabergoline, sold as Cabsar and Dostinex. The latter has not been promoted in the United States for Parkinson's, but has been sold in Japan and some European countries.

Two older agonists, bromocriptine and pergolide, have been used in the United States for years, the article stated, but have not been studied as extensively for early Parkinson's as the new drugs.

After five years of dopamine agonist therapy, patients would need to start levodopa, Koller explained. The delay in introducing its use would postpone dyskinesias and improve the quality of life for patients, he added.

"We can prolong having to use levodopa," Koller said. "We're learning how to use the drugs better and that's what we really want."