title: The mediating role of processing speed in the relationship between depressive symptoms and cognitive function in multiple sclerosis.
abstract: BACKGROUND
  Although disorders of mood and cognition are frequently observed in multiple sclerosis, their relationship remains unclear. We aimed to investigate whether this mood-cognition relationship is mediated by inefficient processing speed, a deficit typically associated with mood symptomatology in the psychiatric literature and a common deficit observed in multiple sclerosis patients.
  
  
  METHODS
  In this study, comprehensive cognitive data and self-reported mood data were retrospectively analyzed from 349 patients with relapsing remitting multiple sclerosis. We performed a bootstrapping analysis to examine whether processing speed provided an indirect means by which depressive symptoms influenced cognitive functioning, specifically memory and executive function.
  
  
  RESULTS
  We observed that processing speed mediated the relationship between depressive symptoms and measures of memory and executive function. Interestingly, exploratory analyses revealed that this mediational role of processing speed was specific to MS patients who were younger, had a lower disability level, and had fewer years since MS diagnosis.
  
  
  CONCLUSIONS
  Together, these findings have implications for mood and cognitive intervention with multiple sclerosis patients.
authors.affiliation: a Department of Cognitive Neurology , Parkwood Institute , London , ON , Canada.
authors.forename: Mervin
authors.initials: M
authors.lastname: Blair
authors.affiliation: a Department of Cognitive Neurology , Parkwood Institute , London , ON , Canada.
authors.forename: Sascha
authors.initials: S
authors.lastname: Gill
authors.affiliation: b Specialized Geriatric Services, Parkwood Institute , London , ON , Canada.
authors.forename: Iris
authors.initials: I
authors.lastname: Gutmanis
authors.affiliation: c Hamilton Health Sciences , Hamilton , ON , Canada.
authors.forename: Kathy
authors.initials: K
authors.lastname: Smolewska
authors.affiliation: c Hamilton Health Sciences , Hamilton , ON , Canada.
authors.forename: Erin
authors.initials: E
authors.lastname: Warriner
authors.affiliation: a Department of Cognitive Neurology , Parkwood Institute , London , ON , Canada.|d Department of Clinical Neurological Sciences, Schulich School of Medicine and Dentistry , Western University , London , ON , Canada.
authors.forename: Sarah A
authors.initials: SA
authors.lastname: Morrow
mesh_terms: D000328:Adult; D060825:Cognitive Dysfunction / Q000209:etiology / Q000503:physiopathology*; D003863:Depression / Q000209:etiology / Q000503:physiopathology*; D056344:Executive Function / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D020529:Multiple Sclerosis, Relapsing-Remitting / Q000150:complications / Q000503:physiopathology*; D011597:Psychomotor Performance / Q000502:physiology*; D012189:Retrospective Studies
keywords: Depressive symptoms; Executive function; Memory; Multiple sclerosis; Processing speed