The actor Michael J. Fox has done much in recent years to bring attention to the devastating impact of Parkinson's disease, a neurological disease that affects control of body movement.

More than half a million people in the U.S. suffer from Parkinson's, and about 50,000 new cases are diagnosed each year. Although the disorder typically begins around age 60, symptoms start before age 40 in about 5 percent of patients, as was the case with Mr. Fox, who was diagnosed at age 30.

Although effective treatments to reduce the hallmark tremors of this disease have been around for years, a new transdermal patch called Neupro® provides another treatment option for patients with early Parkinson's. Neupro contains the drug rotigotine, which has not been used previously in the United States.

Parkinson's disease is caused by the gradual death of the nerve cells that produce dopamine, a chemical neurotransmitter, which transmits signals between nerve cells in the brain.

Since dopamine regulates movement, balance and walking, the resulting reduction in dopamine levels interferes with the passage of messages between areas of the brain that control body movement.

The first sign of the disorder is usually a slight tremor or stiffness in an arm or leg on one side of the body. The tremor generally worsens with stress but may disappear completely during sleep. As the disease progresses, the tremor increases and spreads throughout the body.

The most troublesome symptoms are stiffness or rigidity of the muscles of the arms and legs and a slowing of body movements. Walking becomes shuffling, and making spontaneous facial expressions becomes difficult. Other common manifestations are depression, anxiety, slurred speech, difficulty chewing or swallowing, and memory loss. 

Parkinson's disease is treated with drugs that either raise dopamine levels in the brain or mimic the effects of dopamine, or with some combination of both. The most common treatment for the disorder is Sinemet®, a combination of levodopa, which is converted to dopamine in the brain, and carbidopa, which increases the amount of levodopa reaching the brain. Other drugs can treat the mild symptoms of early Parkinson's disease, either alone or in combination with levodopa.

The need for levodopa can be delayed with dopamine agonists — drugs that mimic the effects of dopamine in the brain. These drugs, however, lose their effectiveness and levodopa often must be added after a few years.

The newly approved rotigotine patch offers another dopamine agonist for early symptoms of Parkinson's disease. The patch, when applied once a day, has been shown to provide immediate, significant improvement of symptoms compared to a placebo patch.

The most common side effects were skin reactions at the patch site and other symptoms typical with the other dopamine agonists, including dizziness, nausea, vomiting, drowsiness and insomnia.

The sudden onset of sleep while driving or operating machinery was a safety concern for study participants using the patch. And, as with the other dopamine agonists, effectiveness of the patch waned rapidly over time.

Despite Neupro's side effects and its short period of action, this new mode of treatment for early Parkinson's may help patients who have not responded well to other agents.