title: Dose-Response of Aerobic Exercise on Cognition: A Community-Based, Pilot Randomized Controlled Trial.
abstract: Epidemiological studies suggest a dose-response relationship exists between physical activity and cognitive outcomes. However, no direct data from randomized trials exists to support these indirect observations. The purpose of this study was to explore the possible relationship of aerobic exercise dose on cognition. Underactive or sedentary participants without cognitive impairment were randomized to one of four groups: no-change control, 75, 150, and 225 minutes per week of moderate-intensity semi-supervised aerobic exercise for 26-weeks in a community setting. Cognitive outcomes were latent residual scores derived from a battery of 16 cognitive tests: Verbal Memory, Visuospatial Processing, Simple Attention, Set Maintenance and Shifting, and Reasoning. Other outcome measures were cardiorespiratory fitness (peak oxygen consumption) and measures of function functional health. In intent-to-treat (ITT) analyses (n = 101), cardiorespiratory fitness increased and perceived disability decreased in a dose-dependent manner across the 4 groups. No other exercise-related effects were observed in ITT analyses. Analyses restricted to individuals who exercised per-protocol (n = 77) demonstrated that Simple Attention improved equivalently across all exercise groups compared to controls and a dose-response relationship was present for Visuospatial Processing. A clear dose-response relationship exists between exercise and cardiorespiratory fitness. Cognitive benefits were apparent at low doses with possible increased benefits in visuospatial function at higher doses but only in those who adhered to the exercise protocol. An individual’s cardiorespiratory fitness response was a better predictor of cognitive gains than exercise dose (i.e., duration) and thus maximizing an individual’s cardiorespiratory fitness may be an important therapeutic target for achieving cognitive benefits.
  
  
  BACKGROUND
  ClinicalTrials.gov NCT01129115.
authors.affiliation: University of Kansas Alzheimer's Disease Center, University of Kansas Medical Center, Fairway, Kansas, United States of America.
authors.forename: Eric D
authors.initials: ED
authors.lastname: Vidoni
authors.affiliation: University of Kansas Alzheimer's Disease Center, University of Kansas Medical Center, Fairway, Kansas, United States of America; Department of Psychology, University of Kansas, Lawrence, Kansas, United States of America.
authors.forename: David K
authors.initials: DK
authors.lastname: Johnson
authors.affiliation: University of Kansas Alzheimer's Disease Center, University of Kansas Medical Center, Fairway, Kansas, United States of America.
authors.forename: Jill K
authors.initials: JK
authors.lastname: Morris
authors.affiliation: University of Kansas Alzheimer's Disease Center, University of Kansas Medical Center, Fairway, Kansas, United States of America.
authors.forename: Angela
authors.initials: A
authors.lastname: Van Sciver
authors.affiliation: University of Kansas Alzheimer's Disease Center, University of Kansas Medical Center, Fairway, Kansas, United States of America.
authors.forename: Colby S
authors.initials: CS
authors.lastname: Greer
authors.affiliation: Department of Physical Therapy and Rehabilitation Science, University of Kansas Medical Center, Kansas City, Kansas, United States of America.
authors.forename: Sandra A
authors.initials: SA
authors.lastname: Billinger
authors.affiliation: Department of Internal Medicine, University of Kansas Medical Center, Kansas City, Kansas, United States of America.
authors.forename: Joseph E
authors.initials: JE
authors.lastname: Donnelly
authors.affiliation: University of Kansas Alzheimer's Disease Center, University of Kansas Medical Center, Fairway, Kansas, United States of America.
authors.forename: Jeffrey M
authors.initials: JM
authors.lastname: Burns
mesh_terms: D000368:Aged; D001288:Attention / Q000502:physiology; D003071:Cognition / Q000502:physiology*; D055812:Community-Based Participatory Research / Q000379:methods; D015444:Exercise / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D017063:Outcome Assessment, Health Care; D010101:Oxygen Consumption / Q000502:physiology*; D010809:Physical Fitness / Q000502:physiology*; D010865:Pilot Projects; D013997:Time Factors