Parkinson's disease is a chronic disorder typically affecting people over age 55. The condition is caused by the death of nerve cells in certain parts of the brain, leading to characteristic problems with movement. These include a "pill rolling" tremor in the hands (so called because it appears that the individual is rolling a small object between thumb and forefinger), difficulty initiating walking, a shuffling gait, decreased facial expressiveness, and trouble talking. Thinking ability may become impaired in later stages of the disease, and depression is common.

Although the underlying cause of Parkinson's disease is unknown, many researchers believe that free radicals may play a role in destroying at least some of the nerve cells.

The nerve cells that are affected in Parkinson's disease work by supplying the neurotransmitter dopamine to another part of the brain. Most treatments for Parkinson's disease work by artificially increasing the brain's dopamine levels. Simply taking dopamine pills won't work, however, because the substance cannot travel from the bloodstream into the brain. Instead, most people with Parkinson's disease take levodopa (L-dopa), which can pass into the brain and be converted there into dopamine. Many people take levodopa with carbidopa, a drug that increases the amount of levodopa available to make dopamine.

At first, levodopa produces dramatic improvement in symptoms; however, over time, levodopa becomes less effective and more likely to produce side effects. Other drugs may be useful as well, including bromocriptine, trihexyphenidyl, entacapone, tolcapone, selegiline, and pergolide. There are also surgical treatments that can decrease symptoms, such as pallidotomy and deep brain stimulation.

CDP-Choline

Short for cytidinediphosphocholine, CDP-choline (sometimes called citicholine) is a substance that occurs naturally in the human body. It is closely related to choline, a nutrient commonly put in the B vitamin family. For reasons that are not completely clear, CDP-choline seems to increase the amount of dopamine in the brain.3,4 On this basis, it has been tried for Parkinson’s disease.

In a 4-week, single-blindstudy of 74 people with Parkinson's disease, researchers tested whether oral CDP-choline might help levodopa be more effective.5 Researchers divided participants into two groups: one group received their usual levodopa dose, the other received half their usual dose without knowing which dosage they were getting. All the participants took 400 mg of oral CDP-choline 3 times daily.

Even though 50% of the participants were taking only half their usual dose of levodopa, both groups scored equally well on standardized tests designed to evaluate the severity of Parkinson's disease symptoms.

Support for the use of CDP-choline also comes from studies in which the supplement was administered by injection.6-9

In general, CDP-choline appears to be safe.11The study of oral CDP-choline for Parkinson's disease reported only a few brief, nonspecific side effects such as nausea, dizziness, and fatigue.12In a study of 2,817 elderly people who took oral CDP-choline for up to 60 days for problems other than Parkinson's disease, side effects were few and mild and reported in only about 5% of participants.13 Two-thirds of these side effects were gastrointestinal (nausea, stomach pain, and diarrhea), and none required stopping CDP-choline. The dose in this study was 550 mg to 650 mg per day, about half the dose used for Parkinson's disease.

Coenzyme Q 10

The supplement coenzyme Q 10 (CoQ 10) been widely advertised as effective for treating Parkinson's disease. However, there is only minimal evidence that it works, and some evidence that it does not.

A study published in 2002 raised hopes that CoQ 10 might help slow the progression of Parkinson’s disease. In this 16-month, double-blind, placebo-controlled trial, 80 people with Parkinson’s disease were given either CoQ 10 (at a dose of 300 mg, 600 mg, or 1,200 mg daily) or placebo. 44 Participants in this trial had early stages of the disease and did not yet need medication. The results appeared to suggest that the supplement, especially at the highest dose, might have slowed disease progression. However, for a variety of statistical reasons, the results were, in fact, quite inconclusive.

A subsequent double-blind, placebo-controlled study of 28 people with Parkinson’s disease, which was well-controlled by medications, indicated that 360 mg of CoQ 10daily could produce a mild improvement in some symptoms.45Based on these results, a more substantial study was undertaken, enrolling 131 people with Parkinson’s disease (again, well-controlled by medications).55 Unfortunately, it didn’t work. While benefits were seen in both the placebo and the CoQ 10 group, the supplement failed to prove more effective than placebo.

For more information, including dosage and safety issues, see the full CoQ10 article.