One of the major medical advances of the last century wasthe demonstration of the loss of dopamine-producing cellsin Parkinson’s disease and the success of levodopa ( L -dopa) to replace the missing neurotransmitter. These Nobel Prizewinning observations are the cornerstone of currenttreatment. In most patients, neurotransmitter replacementby L -dopa, which is converted into dopamine, or by dopamine agonists, provides good symptomatic relief formany years. However, as the disease progresses, thebenefits are lost. The same dose of medication that initiallywas effective loses its potency and does not last as long.Also, involuntary movements (dyskinesias) appear, as seenvividly on television in Michael J. Fox. Furthermore, re-placement therapy does not stop the progression of thedisease, and some neurologists argue that L -dopa treatment actually causes disease progression.