Fig. 2

Delayed-start design with beneficial effect of early treatment with levodopa. If a beneficial disease modifying effect of levodopa exists, patients in the early-start group will perform better at the end of the study than patients in the delayed-start group if phase 1 is sufficiently long and if the beneficial disease modifying effect is maintained during phase 2. The small improvement of the delayed-start group at the start of phase 1 and of the early-start group at the start of phase 2 represents the placebo-effect