title: Levodopa Is a Double-Edged Sword for Balance and Gait in People With Parkinson's Disease.
abstract: BACKGROUND
  The effects of levodopa on balance and gait function in people with Parkinson's disease (PD) is controversial. This study compared the relative responsiveness to l-dopa on six domains of balance and gait: postural sway in stance; gait pace; dynamic stability; gait initiation; arm swing; and turning in people with mild and severe PD, with and without dyskinesia.
  
  
  METHODS
  We studied 104 subjects with idiopathic PD (H & Y II [n = 52] and III-IV [n = 52]) and 64 age-matched controls. Subjects performed a mobility task in the practical off state and on l-dopa: standing quietly for 30 seconds, initiating gait, walking 7 meters, and turning 180 degrees. Thirty-four measures of mobility were computed from inertial sensors. Standardized response means were used to determine relative responsiveness to l-dopa.
  
  
  RESULTS
  The largest improvements with l-dopa were found for arm swing and pace-related gait measures. Gait dynamic stability was unaffected by PD and not responsive to l-dopa. l-dopa reduced turning duration, but only in subjects with severe PD. In contrast to gait, postural sway in quiet standing increased with l-dopa, especially in the more severely affected subjects. The increase in postural sway, as well as decrease in turning duration and exaggerated arm swing with l-dopa was observed only for subjects with dyskinesia at the time of testing.
  
  
  CONCLUSIONS
  The observed spectrum of l-dopa responsiveness in balance and gait measures suggests that multiple neural circuits control balance and gait. Many of the negative effects of l-dopa may be directly or indirectly caused by dyskinesia.
authors.affiliation: Department of Neurology, School of Medicine, Oregon Health & Science University, Portland, Oregon, USA.
authors.forename: Carolin
authors.initials: C
authors.lastname: Curtze
authors.affiliation: Department of Neurology, School of Medicine, Oregon Health & Science University, Portland, Oregon, USA.
authors.forename: John G
authors.initials: JG
authors.lastname: Nutt
authors.affiliation: Department of Neurology, School of Medicine, Oregon Health & Science University, Portland, Oregon, USA.
authors.forename: Patricia
authors.initials: P
authors.lastname: Carlson-Kuhta
authors.affiliation: Department of Neurology, School of Medicine, Oregon Health & Science University, Portland, Oregon, USA.
authors.forename: Martina
authors.initials: M
authors.lastname: Mancini
authors.affiliation: Department of Neurology, School of Medicine, Oregon Health & Science University, Portland, Oregon, USA.|VA Portland Health Care System, Portland, Oregon, USA.
authors.forename: Fay B
authors.initials: FB
authors.lastname: Horak
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000978:Antiparkinson Agents / Q000009:adverse effects / Q000494:pharmacology*; D005080:Exercise Test; D005260:Female; D005684:Gait / Q000187:drug effects* / Q000502:physiology; D006801:Humans; D007980:Levodopa / Q000009:adverse effects / Q000494:pharmacology*; D008297:Male; D008875:Middle Aged; D017063:Outcome Assessment, Health Care; D010300:Parkinson Disease / Q000188:drug therapy* / Q000503:physiopathology*; D004856:Postural Balance / Q000187:drug effects* / Q000502:physiology; D012720:Severity of Illness Index
chemical_list: D000978:Antiparkinson Agents; D007980:Levodopa
keywords: Parkinson's disease; balance; gait; inertial sensors; levodopa