title: Characteristics of the sequence effect in Parkinson's disease.
abstract: The sequence effect (SE) in Parkinson's disease (PD) is progressive slowing of sequential movements. It is a feature of bradykinesia, but is separate from a general slowness without deterioration over time. It is commonly seen in PD, but its physiology is unclear. We measured general slowness and the SE separately with a computer-based, modified Purdue pegboard in 11 patients with advanced PD. We conducted a placebo-controlled, four-way crossover study to learn whether levodopa and repetitive transcranial magnetic stimulation (rTMS) could improve general slowness or the SE. We also examined the correlation between the SE and clinical fatigue. Levodopa alone and rTMS alone improved general slowness, but rTMS showed no additive effect on levodopa. Levodopa alone, rTMS alone, and their combination did not alleviate the SE. There was no correlation between the SE and fatigue. This study suggests that dopaminergic dysfunction and abnormal motor cortex excitability are not the relevant mechanisms for the SE. Additionally, the SE is not a component of clinical fatigue. Further work is needed to establish the physiology and clinical relevance of the SE. © 2010 Movement Disorder Society.
authors.affiliation: Human Motor Control Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20892-1428, USA.
authors.forename: Suk Yun
authors.initials: SY
authors.lastname: Kang
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Wasaka
authors.forename: Ejaz A
authors.initials: EA
authors.lastname: Shamim
authors.forename: Sungyoung
authors.initials: S
authors.lastname: Auh
authors.forename: Yoshino
authors.initials: Y
authors.lastname: Ueki
authors.forename: Grisel J
authors.initials: GJ
authors.lastname: Lopez
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Kida
authors.forename: Seung-Hyun
authors.initials: SH
authors.lastname: Jin
authors.forename: Nguyet
authors.initials: N
authors.lastname: Dang
authors.forename: Mark
authors.initials: M
authors.lastname: Hallett
mesh_terms: D000368:Aged; D000978:Antiparkinson Agents / Q000494:pharmacology / Q000627:therapeutic use; D018592:Cross-Over Studies; D004185:Disability Evaluation; D018450:Disease Progression; D005260:Female; D006801:Humans; D007980:Levodopa / Q000494:pharmacology / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D009068:Movement / Q000187:drug effects / Q000502:physiology*; D010300:Parkinson Disease / Q000503:physiopathology* / Q000628:therapy; D011597:Psychomotor Performance / Q000187:drug effects / Q000502:physiology*; D012720:Severity of Illness Index; D050781:Transcranial Magnetic Stimulation / Q000379:methods
chemical_list: D000978:Antiparkinson Agents; D007980:Levodopa