title: Is implicit sequence learning impaired in Parkinson's disease? A meta-analysis.
abstract: The aim of the present study was to examine impairment of implicit learning in Parkinson's disease (PD) by means of a meta-analysis of studies that used the serial reaction time (SRT) task. The authors performed a systematic review and meta-analysis of published journal articles (1987-2005) that used the SRT task with patients with PD. The principal outcome measures used to compare studies were (a) the difference in reaction time between the last block of ordered sequence trials and the randomized block for PD and control participants and (b) fixed and random effects pooled estimates by the inverse weighting method. Six studies, including 67 patients with PD, met the inclusion criteria. The meta-analysis showed that implicit learning was impaired in PD, relative to healthy controls, with a standardized mean difference of 0.73 (95% confidence interval = 0.38, 1.07). Implicit sequence learning appears to be impaired in patients with PD. Some common methodological weaknesses and limitations in the reporting of statistical data are discussed.
authors.affiliation: Department of Medicine, Wellington School of Medicine and Health Sciences, University of Otago, Wellington South, New Zealand. rsiegert@wnmeds.ac.nz
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Siegert
authors.forename: Kathryn D
authors.initials: KD
authors.lastname: Taylor
authors.forename: Mark
authors.initials: M
authors.lastname: Weatherall
authors.forename: David A
authors.initials: DA
authors.lastname: Abernethy
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D016001:Confidence Intervals; D005260:Female; D006801:Humans; D007859:Learning Disabilities / Q000503:physiopathology*; D008297:Male; D015201:Meta-Analysis as Topic; D008875:Middle Aged; D009483:Neuropsychological Tests / Q000706:statistics & numerical data; D010300:Parkinson Disease / Q000503:physiopathology*; D011930:Reaction Time / Q000502:physiology; D012196:Review Literature as Topic; D012691:Serial Learning / Q000502:physiology*