Constant V.M. Verschuur, M.D., from Amsterdam Neuroscience, and colleagues randomly assigned patients with early Parkinson disease to receive either levodopa (three times per day) in combination with carbidopa for 80 weeks (early-start group) or placebo for 40 weeks followed by levodopa in combination with carbidopa for 40 weeks (delayed-start group; 222 and 223 patients, respectively)....