title: Reduced information processing speed as primum movens for cognitive decline in MS.
abstract: BACKGROUND
  Cognitive impairment affects half of the multiple sclerosis (MS) patient population and is an important contributor to patients' daily activities. Most cognitive impairment studies in MS are, however, cross-sectional or/and focused on the early disease stages.
  
  
  OBJECTIVE
  We aim to assess the time course of decline of different cognitive domains.
  
  
  METHODS
  We collected neuropsychological data on 514 MS patients to construct Kaplan-Meier survival curves of the tests included in the Neuropsychological Screening Battery for MS (NSBMS) and the Symbol Digit Modalities Test (SDMT). Cox-proportional hazard models were constructed to examine the influence of MS onset type, age at onset, gender, depression and level of education on the time course, expressed as age or disease.
  
  
  RESULTS
  Survival curves of tests focusing on information processing speed (IPS) declined significantly faster than tests with less specific demands of IPS. Median age for pathological decline was 56.2 years (95% CI: 54.4-58.2) on the SDMT and 63.9 years (95% CI: 60-66.9) on the CLTR, a memory task.
  
  
  CONCLUSIONS
  In conclusion, IPS is the cognitive domain not only most widely affected by MS but it is also the first cognitive deficit to emerge in MS.
authors.affiliation: Center for Neurosciences, UZ Brussel, Vrije Universiteit Brussel (VUB) Brussels/Faculté de Psychologie et des sciences de l'éducation, Place du Parc, 20 UMons, Mons, Belgium Jeroen.Van.Schependom@vub.ac.be.
authors.forename: Jeroen
authors.initials: J
authors.lastname: Van Schependom
authors.affiliation: Center for Neurosciences, UZ Brussel, Vrije Universiteit Brussel (VUB), Brussels, Belgium.
authors.forename: Marie B
authors.initials: MB
authors.lastname: D'hooghe
authors.affiliation: National MS Center Melsbroek, Belgium.
authors.forename: Krista
authors.initials: K
authors.lastname: Cleynhens
authors.affiliation: National MS Center Melsbroek, Belgium.
authors.forename: Mieke
authors.initials: M
authors.lastname: D'hooge
authors.affiliation: Faculté de Psychologie et des sciences de l'éducation, Place du Parc, 20 UMons, Mons, Belgium.
authors.forename: Marie-Claire
authors.initials: MC
authors.lastname: Haelewyck
authors.affiliation: Center for Neurosciences UZ Brussel Vrije Universiteit Brussel (VUB), Brussels/University Medical Center Groningen, Groningen, The Netherlands.
authors.forename: Jacques
authors.initials: J
authors.lastname: De Keyser
authors.affiliation: Center for Neurosciences, UZ Brussel, Vrije Universiteit Brussel (VUB), Brussels/Faculté de Psychologie et des sciences de l'éducation, Place du Parc, 20 UMons, Mons/National MS Center Melsbroek, Belgium.
authors.forename: Guy
authors.initials: G
authors.lastname: Nagels
mesh_terms: D000328:Adult; D003072:Cognition Disorders / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology*; D018450:Disease Progression; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009103:Multiple Sclerosis / Q000150:complications / Q000503:physiopathology*; D009483:Neuropsychological Tests / Q000706:statistics & numerical data*; D016016:Proportional Hazards Models
keywords: NSBMS; SDMT; Survival analysis; cognitive decline; multiple sclerosis