Early pharmacologic treatment in Parkinson's disease.

Early treatment of Parkinson's disease (PD) affords an opportunity to forestall clinical progression. Levodopa is the most effective treatment for PD motor signs and symptoms, but its use is associated with the development of motor fluctuations and dyskinesias. Because of this, levodopa use is commonly withheld until the patient experiences functional disability. Other medications are available for the treatment of early PD and can be initiated at or near the time of diagnosis. Monoamine oxidase type B (MAO-B) inhibitors provide mild symptomatic benefit, delay the need for levodopa, are very well tolerated, and may provide long-term disease-modifying effects. Dopamine agonists provide moderate symptomatic benefit, delay the need for levodopa, and cause fewer motor complications than levodopa. Compared with levodopa, however, dopamine agonists cause more somnolence and sudden-onset sleep as well as impulse control disorders. The treatment of early PD depends in part on the individual patient's anticipated risk of side effects and the degree of motor improvement required. Physicians should also consider the early use of MAO-B inhibitors in light of their very good tolerability and the recent evidence suggesting long-term disease-modifying effects.