In both groups , Unified Parkinson 's Disease Rating Scale Section II ( UPDRS II ) , UPDRS III , 6-minute walking test ( 6MWT ) , Timed Up-and-Go test ( TUG ) ; PD Disability Scale ( PDDS ) , and l-dopa equivalents were assessed at baseline ( T0 ) , 6 months ( T1 ) , 1 year ( T2 ) , 18 months ( T3 ) , and 2 years ( T4 ) later .