title: Depressive symptomology in multiple sclerosis: Disability, cardiorespiratory fitness and heart rate variability.
abstract: OBJECTIVE
  This study aimed to investigate whether neurological disability status, heart rate variability (HRV), cardiorespiratory fitness (CRF) explained the variance in depressive symptoms in multiple sclerosis (MS).
  
  
  METHODS
  Associations between CRF (via maximal oxygen uptake; VO2peak), HRV indices of normalized ultra-low (nULF) and very low frequency domains (nVLF), neurological disability status and depressive symptoms (using the Depression subscale of the Hospital Anxiety Depression Scale; HADS-D) were assessed in 53 participants with MS and 17 matched controls. Hierarchical linear regression analysis was conducted within the MS subsample to examine the variance explained by neurological disability alone and CRF.
  
  
  RESULTS
  The groups were similar in mean age (MS=52.0 years, Control=51.1 years) and sex (MS=72% female, Control=77% female). Among individuals with MS, HADS-D scores significantly correlated with disability status (sample mean score=4) and VO2peak(r=-.62, P<.001), whereas VO2peakonly correlated with nVLF (r=0.29, P<.05), but not nULF (r=0.26, P=.06). The hierarchical linear regression indicated that VO2peak(P<.05) attenuated the effect of disability status on HADS-D scores such that disability was no longer a predictor of depressive symptomology at step 2 (P>.05).
  
  
  CONCLUSIONS
  Heart rate variability does not seem to significantly differ between individuals with MS and healthy controls. When accounting for CRF, disability status no longer explains significant variance in depressive symptoms in MS. Accordingly, targeting CRF might be an effective approach for effectively managing depressive symptoms in individuals with MS.
authors.affiliation: Department of Kinesiology and Community Health, University of Illinois Urbana-Champaign, Urbana, IL, USA.
authors.forename: I
authors.identifier: http://orcid.org/0000-0001-7745-8501
authors.initials: I
authors.lastname: Ensari
authors.affiliation: Department of Kinesiology and Community Health, University of Illinois Urbana-Champaign, Urbana, IL, USA.
authors.forename: L A
authors.initials: LA
authors.lastname: Pilutti
authors.affiliation: Department of Kinesiology and Community Health, University of Illinois Urbana-Champaign, Urbana, IL, USA.
authors.forename: R W
authors.initials: RW
authors.lastname: Motl
mesh_terms: D000072599:Cardiorespiratory Fitness / Q000502:physiology*; D003863:Depression / Q000150:complications / Q000175:diagnosis* / Q000503:physiopathology / Q000523:psychology; D006233:Persons with Disabilities; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009103:Multiple Sclerosis / Q000150:complications / Q000503:physiopathology* / Q000523:psychology
keywords: Hospital Anxiety Depression Scale; aerobic fitness; autonomic function; depressive; heart rate variability; multiple sclerosis