Figure 1.

Protocol for randomized, double-blinded, placebo-controlled, crossover trial of inhalation of true and placebo hydrogen gas for 4 weeks.

Note: The odor stick identification test for Japanese (OSIT-J), the Unified Parkinson's Disease Rating Scale scores 1 and 2 (UPDRS1 and UPDRS2), and quantification of urinary 8-hydroxy-2′-deoxyguanine (8-OHdG) normalized for urinary creatinine (Cre) were performed at the indicated time points. w: Weeks.