ONLINE FIRST
Activity Energy Expenditure and Incident
Cognitive Impairment in Older Adults
Laura E.
Middleton, PhD; Todd M. Manini, PhD; Eleanor M. Simonsick, PhD; Tamara B. Harris, MD, MS; Deborah E. Barnes, PhD; Frances Tylavsky, DrPH; Jennifer S. Brach, PhD, PT; James E. Everhart, MD, MPH; Kristine Yaffe, MD
Arch Intern Med. 2011;171(14):1251-1257.
doi:10.1001/archinternmed.2011.277
Background
Studies suggest that physically active peoplehave
reduced risk of incident cognitive impairment in late life.However,
these studies are limited by reliance on self-reportsof physical
activity, which only moderately correlate with objectivemeasures
and often exclude activity not readily quantifiableby frequency and
duration. The objective of this study was toinvestigate the
relationship between activity energy expenditure(AEE), an objective
measure of total activity, and incidenceof cognitive impairment.
Methods We
calculated AEE as 90% of total energy expenditure(assessed during 2
weeks using doubly labeled water) minus restingmetabolic rate
(measured using indirect calorimetry) in 197men and women (mean
age, 74.8 years) who were free of mobilityand cognitive impairments
at study baseline (1998-1999). Cognitivefunction was assessed at
baseline and 2 or 5 years later usingthe Modified Mini-Mental State
Examination. Cognitive impairmentwas defined as a decline of at
least 1.0 SD (9 points) betweenbaseline and follow-up evaluations.
Results After
adjustment for baseline Modified Mini-MentalState Examination
scores, demographics, fat-free mass, sleepduration, self-reported
health, and diabetes mellitus, olderadults in the highest
sex-specific tertile of AEE had lowerodds of incident cognitive
impairment than those in the lowesttertile (odds ratio, 0.09; 95%
confidence interval, 0.01-0.79).There was also a significant dose
response between AEE and incidenceof cognitive impairment (P
= .05 for trend over tertiles).
Conclusions
These findings indicate that greater AEE maybe
protective against cognitive impairment in a dose-responsemanner.
The significance of overall activity in contrast tovigorous or
light activity should be determined.
Author Affiliations: Heart and Stroke
Foundation Centre for Stroke Recovery, Sunnybrook Health Sciences Centre,
Toronto, Ontario, Canada (Dr Middleton); Department of Aging and Geriatric
Research, University of Florida, Gainesville (Dr Manini); Clinical Research
Branch (Dr Simonsick) and Laboratory of Epidemiology, Demography, and Biometry(Dr Harris), National Institute on Aging, Bethesda, Maryland; Department of Psychiatry, San Francisco Veterans Affairs Medical Center, San Francisco, California(Drs Barnes and Yaffe); Departments of Psychiatry (Drs Barnes and Yaffe), Neurology (Dr Yaffe), and Epidemiology and Biostatistics (Dr Yaffe), School of Medicine, University of California, San Francisco; Department of Biostatistics and Epidemiology, University of Tennessee, Memphis (Dr Tylavsky); Department of Physical Therapy, University of Pittsburgh, Pittsburgh, Pennsylvania (Dr Brach); and Epidemiology and Data Systems Program, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, Maryland (Dr Everhart).
