title: The association between midlife cardiorespiratory fitness levels and later-life dementia: a cohort study.
abstract: BACKGROUND
  Primary prevention of Alzheimer disease and other types of dementia (all-cause dementia) is an important public health goal. Evidence to date is insufficient to recommend any lifestyle change to prevent or delay the onset of dementia.
  
  
  OBJECTIVE
  To assess the association between objectively measured midlife cardiorespiratory fitness ("fitness") levels and development of all-cause dementia in advanced age.
  
  
  METHODS
  Prospective, observational cohort study.
  
  
  METHODS
  Preventive medicine clinic.
  
  
  METHODS
  19 458 community-dwelling, nonelderly adults who had a baseline fitness examination.
  
  
  METHODS
  Fitness levels, assessed using the modified Balke treadmill protocol between 1971 and 2009, and incident all-cause dementia using Medicare Parts A and B claims data from 1999 to 2009.
  
  
  RESULTS
  1659 cases of incident all-cause dementia occurred during 125 700 person-years of Medicare follow-up (median follow-up, 25 years [interquartile range, 19 to 30 years]). After multivariable adjustment, participants in the highest quintile of fitness level had lower hazard of all-cause dementia than those in the lowest quintile (hazard ratio, 0.64 [95% CI, 0.54 to 0.77]). Higher fitness levels were associated with lower hazard of all-cause dementia with previous stroke (hazard ratio, 0.74 [CI, 0.53 to 1.04]) or without previous stroke (hazard ratio, 0.74 [CI, 0.61 to 0.90]).
  
  
  CONCLUSIONS
  Dementia diagnoses were based on Medicare claims, and participants generally were non-Hispanic white, healthy, and well-educated and had access to preventive health care. This study evaluated fitness levels, so a specific exercise prescription cannot be generated from results and the findings may not be causal.
  
  
  CONCLUSIONS
  Higher midlife fitness levels seem to be associated with lower hazards of developing all-cause dementia later in life. The magnitude and direction of the association were similar with or without previous stroke, suggesting that higher fitness levels earlier in life may lower risk for dementia later in life, independent of cerebrovascular disease.
  
  
  BACKGROUND
  The Cooper Institute; University of Texas Southwestern Medical Center; National Heart, Lung, and Blood Institute; and American Heart Association.
authors: The Cooper Institute and University of Texas Southwestern Medical Center, Dallas, Texas, USA. ldefina@cooperinst.org
authors: Laura F
authors: LF
authors: Defina
authors: Benjamin L
authors: BL
authors: Willis
authors: Nina B
authors: NB
authors: Radford
authors: Ang
authors: A
authors: Gao
authors: David
authors: D
authors: Leonard
authors: William L
authors: WL
authors: Haskell
authors: Myron F
authors: MF
authors: Weiner
authors: Jarett D
authors: JD
authors: Berry
mesh_terms: D000328:Adult; D000368:Aged; D000544:Alzheimer Disease / Q000209:etiology / Q000517:prevention & control; D002320:Cardiovascular Physiological Phenomena; D003704:Dementia / Q000209:etiology / Q000517:prevention & control*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged / Q000502:physiology*; D010809:Physical Fitness; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012307:Risk Factors
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