title: Mental slowness in patients with Parkinson's disease: Associations with cognitive functions?
abstract: Motor slowness (bradykinesia) is a core feature of Parkinson's disease (PD). It is often assumed that patients show mental slowness (bradyphrenia) as well; however, evidence for this is debated. The aims of this study were to determine whether PD patients show mental slowness apart from motor slowness and, if this is the case, to what extent this affects their performance on neuropsychological tests of attention, memory, and executive functions (EF).
  
  
  
  Fifty-five nondemented PD patients and 65 healthy controls were assessed with a simple information-processing task in which reaction and motor times could be separated. In addition, all patients and a second control group (N = 138) were assessed with neuropsychological tests of attention, memory, and EF.
  
  
  
  While PD patients showed significantly longer reaction times than healthy controls, their motor times were not significantly longer. Reaction and motor times were only moderately correlated and were not related to clinical measures of disease severity. PD patients performed significantly worse on tests of attention and EF, and for the majority of neuropsychological tests 11-51% of the patients showed a clinically impaired performance. Reaction times did not, however, predict patients' test performance, while motor times were found to have a significant negative influence on tests of attention.
  
  
  
  PD patients show mental slowness, which can be separated from motor slowness. Neuropsychological test performance is not influenced by mental slowness; however, motor slowness can have a negative impact. When interpreting neuropsychological test performance of PD patients in clinical practice, motor slowness needs to be taken into account.
authors.affiliation: a Department of Clinical & Developmental Neuropsychology , University of Groningen , Groningen , The Netherlands.
authors.forename: Thialda T
authors.initials: TT
authors.lastname: Vlagsma
authors.affiliation: a Department of Clinical & Developmental Neuropsychology , University of Groningen , Groningen , The Netherlands.
authors.forename: Janneke
authors.initials: J
authors.lastname: Koerts
authors.affiliation: a Department of Clinical & Developmental Neuropsychology , University of Groningen , Groningen , The Netherlands.
authors.forename: Oliver
authors.initials: O
authors.lastname: Tucha
authors.affiliation: b Department of Medical Psychology , Medical Center Nij Smellinghe , Drachten , The Netherlands.
authors.forename: Hilde T
authors.initials: HT
authors.lastname: Dijkstra
authors.affiliation: c Department of Psychiatry and Psychology , Maastricht University Medical Center , Maastricht , The Netherlands.
authors.forename: Annelien A
authors.initials: AA
authors.lastname: Duits
authors.affiliation: d Department of Neurology , University Medical Center Groningen , Groningen , The Netherlands.
authors.forename: Teus
authors.initials: T
authors.lastname: van Laar
authors.affiliation: a Department of Clinical & Developmental Neuropsychology , University of Groningen , Groningen , The Netherlands.|d Department of Neurology , University Medical Center Groningen , Groningen , The Netherlands.
authors.forename: Jacoba M
authors.initials: JM
authors.lastname: Spikman
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001288:Attention / Q000502:physiology; D003071:Cognition / Q000502:physiology*; D056344:Executive Function / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D008568:Memory / Q000502:physiology; D008875:Middle Aged; D009483:Neuropsychological Tests; D010300:Parkinson Disease / Q000523:psychology*; D011930:Reaction Time / Q000502:physiology*
keywords: Bradyphrenia; Cognitive functions; Motor slowness; Neuropsychological assessment; Parkinson’s disease