title: Correlation between midline gait function performance and verbal fluency in patients with Parkinson's disease.
abstract: BACKGROUND
  Verbal fluency impairments are among the earliest and most common cognitive deficits in Parkinson's disease (PD), yet more than one study has shown that as a group, verbal fluency performance is not always different between patients with PD and age-matched controls. Here we examined whether PD-related deficits in speech and language capabilities are detectable in patients who exhibit poor midline motor function, such as control of gait. We postulated that if phonemic verbal fluency (PVF) performance in PD is dissociable from other factors such as age in this patient subgroup, a low PVF will likely reflect a general cognitive-motor deficit attributable to Parkinsonian pathology.
  
  
  METHODS
  Thirty-one PD and thirteen controls were evaluated on PVF and the Metronome-Paced Square Step Test (MPSST), a complex sensorimotor task that challenges axial and midline function. The MPSST requires a patient to initiate and maintain a consecutive series of diagonal and midline cross-over steps during the test.
  
  
  RESULTS
  We found that despite similar PVF performance between groups, the vast majority of controls but not patients completed the MPSST without any errors, and the odds of completing the MPSST without any errors was 15 times greater among control. More importantly, a significant amount of PVF variability was explained by MPSST performance in PD but not controls even after controlling for age and disease duration.
  
  
  CONCLUSIONS
  Together, these results provide evidence that PVF performance in PD likely reflects a PD-specific process and suggests that the MPSST may be a more sensitive test of PD-specific pathology than PVF.
authors.affiliation: Division of Experimental Neuroscience, Department of Clinical Neurosciences, Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, AB, T2N 4N1, Canada. tgchomia@ucalgary.ca.|Health Research Innovation Centre, Room 1AC60, 3330 Hospital Drive NW, Calgary, AB, T2N 4N1, Canada. tgchomia@ucalgary.ca.
authors.forename: Taylor
authors.initials: T
authors.lastname: Chomiak
authors.affiliation: Division of Experimental Neuroscience, Department of Clinical Neurosciences, Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, AB, T2N 4N1, Canada.
authors.forename: Nicole
authors.initials: N
authors.lastname: Meyer
authors.affiliation: Division of Experimental Neuroscience, Department of Clinical Neurosciences, Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, AB, T2N 4N1, Canada.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Cihal
authors.affiliation: Division of Experimental Neuroscience, Department of Clinical Neurosciences, Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, AB, T2N 4N1, Canada.
authors.forename: Julia
authors.initials: J
authors.lastname: Johnson
authors.affiliation: Division of Experimental Neuroscience, Department of Clinical Neurosciences, Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, AB, T2N 4N1, Canada.
authors.forename: Conrad
authors.initials: C
authors.lastname: Crofts
authors.affiliation: Division of Experimental Neuroscience, Department of Clinical Neurosciences, Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, AB, T2N 4N1, Canada. hub@ucalgary.ca.|Health Research Innovation Centre, Room 1AC60, 3330 Hospital Drive NW, Calgary, AB, T2N 4N1, Canada. hub@ucalgary.ca.
authors.forename: Bin
authors.initials: B
authors.lastname: Hu
mesh_terms: D000368:Aged; D005080:Exercise Test; D005260:Female; D005684:Gait; D006801:Humans; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000503:physiopathology* / Q000523:psychology; D014705:Verbal Behavior
keywords: Cognitive impairment; Midline stepping; Parkinson’s disease