If you have Parkinsons disease and take levodopa, this is important news. A recent study found that the drug may cause elevated homocysteine. Furthermore, as the dose of levodopa increases, so does the noxious homocysteine. The critical dose of levodopa is 300 mg daily. And, the higher the homocysteine, the worse the Parkinsons symptoms. Subjects with homocysteine levels greater than 14 mcmol/L fared worse on higher cognitive function and memory tests.
Action to take: The best way to beat Parkinsons disease is not to get it. You may already know pesticides, bowel toxicity, chemical poisoning, and nutrient deficiencies raise your risk. Now the very drug designed to treat it causes it to get worse. If you take levodopa, please implore your doctor to check your homocysteine level. If its high, use the supplements mentioned previously to help keep it down.
One final note: New evidence shows that type-2 diabetes increases your risk of Parkinsons. A Finnish study on 51,552 men and women concluded that type-2 diabetes will raise your risk of Parkinsons by 80%. That is a huge risk factor, so work hard to reduce your risk for type-2 diabetes. You can find the best ways to fight it on my website (see page 6 for website details).
Ref: Hu, G., Jousilahti, P., et al. Type-2 diabetes and the risk of Parkinsons disease, Diabetes Care, 2007 January 24.