title: Total daily physical activity and the risk of AD and cognitive decline in older adults.
abstract: OBJECTIVE
  Studies examining the link between objective measures of total daily physical activity and incident Alzheimer disease (AD) are lacking. We tested the hypothesis that an objective measure of total daily physical activity predicts incident AD and cognitive decline.
  
  
  METHODS
  Total daily exercise and nonexercise physical activity was measured continuously for up to 10 days with actigraphy (Actical®; Philips Healthcare, Bend, OR) from 716 older individuals without dementia participating in the Rush Memory and Aging Project, a prospective, observational cohort study. All participants underwent structured annual clinical examination including a battery of 19 cognitive tests.
  
  
  RESULTS
  During an average follow-up of about 4 years, 71 subjects developed clinical AD. In a Cox proportional hazards model adjusting for age, sex, and education, total daily physical activity was associated with incident AD (hazard ratio = 0.477; 95% confidence interval 0.273-0.832). The association remained after adjusting for self-report physical, social, and cognitive activities, as well as current level of motor function, depressive symptoms, chronic health conditions, and APOE allele status. In a linear mixed-effect model, the level of total daily physical activity was associated with the rate of global cognitive decline (estimate 0.033, SE 0.012, p = 0.007).
  
  
  CONCLUSIONS
  A higher level of total daily physical activity is associated with a reduced risk of AD.
authors.affiliation: Rush Alzheimer’s Disease Center, Rush University Medical Center, Chicago, IL, USA. Aron_S_Buchman@rush.edu
authors.forename: A S
authors.initials: AS
authors.lastname: Buchman
authors.forename: P A
authors.initials: PA
authors.lastname: Boyle
authors.forename: L
authors.initials: L
authors.lastname: Yu
authors.forename: R C
authors.initials: RC
authors.lastname: Shah
authors.forename: R S
authors.initials: RS
authors.lastname: Wilson
authors.forename: D A
authors.initials: DA
authors.lastname: Bennett
mesh_terms: D000203:Activities of Daily Living; D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000453:epidemiology*; D015992:Body Mass Index; D015984:Causality; D003072:Cognition Disorders / Q000175:diagnosis / Q000453:epidemiology*; D015897:Comorbidity; D004522:Educational Status; D004734:Energy Metabolism; D015444:Exercise; D005260:Female; D006801:Humans; D008019:Life Style; D008297:Male; D009043:Motor Activity; D016016:Proportional Hazards Models; D012307:Risk Factors; D017678:Sex Distribution; D012737:Sex Factors