title: Activity energy expenditure and incident cognitive impairment in older adults.
abstract: BACKGROUND
  Studies suggest that physically active people have reduced risk of incident cognitive impairment in late life. However, these studies are limited by reliance on self-reports of physical activity, which only moderately correlate with objective measures and often exclude activity not readily quantifiable by frequency and duration. The objective of this study was to investigate the relationship between activity energy expenditure (AEE), an objective measure of total activity, and incidence of cognitive impairment.
  
  
  METHODS
  We calculated AEE as 90% of total energy expenditure (assessed during 2 weeks using doubly labeled water) minus resting metabolic rate (measured using indirect calorimetry) in 197 men and women (mean age, 74.8 years) who were free of mobility and cognitive impairments at study baseline (1998-1999). Cognitive function was assessed at baseline and 2 or 5 years later using the Modified Mini-Mental State Examination. Cognitive impairment was defined as a decline of at least 1.0 SD (9 points) between baseline and follow-up evaluations.
  
  
  RESULTS
  After adjustment for baseline Modified Mini-Mental State Examination scores, demographics, fat-free mass, sleep duration, self-reported health, and diabetes mellitus, older adults in the highest sex-specific tertile of AEE had lower odds of incident cognitive impairment than those in the lowest tertile (odds ratio, 0.09; 95% confidence interval, 0.01-0.79). There was also a significant dose response between AEE and incidence of cognitive impairment (P = .05 for trend over tertiles).
  
  
  CONCLUSIONS
  These findings indicate that greater AEE may be protective against cognitive impairment in a dose-response manner. The significance of overall activity in contrast to vigorous or light activity should be determined.
authors.affiliation: Heart and Stroke Foundation Centre for Stroke Recovery, Sunnybrook Research Institute, 2075 Bayview Ave, A421, Toronto, ON M4N 3M5, Canada. Middleton_l@hotmail.com
authors.forename: Laura E
authors.initials: LE
authors.lastname: Middleton
authors.forename: Todd M
authors.initials: TM
authors.lastname: Manini
authors.forename: Eleanor M
authors.initials: EM
authors.lastname: Simonsick
authors.forename: Tamara B
authors.initials: TB
authors.lastname: Harris
authors.forename: Deborah E
authors.initials: DE
authors.lastname: Barnes
authors.forename: Frances
authors.initials: F
authors.lastname: Tylavsky
authors.forename: Jennifer S
authors.initials: JS
authors.lastname: Brach
authors.forename: James E
authors.initials: JE
authors.lastname: Everhart
authors.forename: Kristine
authors.initials: K
authors.lastname: Yaffe
mesh_terms: D000203:Activities of Daily Living; D000368:Aged; D000369:Aged, 80 and over; D001481:Basal Metabolism; D001823:Body Composition; D003072:Cognition Disorders / Q000453:epidemiology* / Q000517:prevention & control; D048909:Diabetes Complications / Q000453:epidemiology; D004734:Energy Metabolism; D015444:Exercise; D005260:Female; D005500:Follow-Up Studies; D006304:Health Status; D006801:Humans; D015994:Incidence; D016015:Logistic Models; D008297:Male; D016017:Odds Ratio; D005082:Physical Exertion; D012494:Sampling Studies; D012647:Self-Assessment; D012890:Sleep