title: Physical activity and cognition in old age.
abstract: OBJECTIVE
  With the rapid ageing of the world's population, investigating protective factors that may prevent or delay age-related disorders has become a new public health priority. Dementia is a common age-related disorder, affecting up to one in every two people reaching 80 years of age or above. Amongst the various potential 'protective factors' currently under investigation, physical activity seems to hold promise for the primary and the secondary prevention of dementia. This paper critically reviews the evidence in support of the association between exercise and cognitive decline/dementia, as reported by cohort studies or clinical trials.
  
  
  RESULTS
  The results of cohort studies show that physical activity is associated with better cognitive function and less cognitive decline in later life although there is only scant evidence suggesting that physical activity may in fact reduce the risk of dementia and Alzheimer's disease. In addition, data to support the systematic introduction of physical activity programmes to reduce the risk of dementia in later life are not as yet available from randomized clinical trials.
  
  
  CONCLUSIONS
  The results of observational studies are largely consistent with the hypothesis that physical activity reduces the risk of cognitive decline and dementia in later life. These findings are, however, not as yet adequately supported by data from randomized clinical trials.
authors.affiliation: School of Psychiatry and Clinical Neurosciences, University of Western Australia, Perth, Western Australia, Australia. nicolal@cyllene.uwa.edu.au
authors.forename: Nicola T
authors.initials: NT
authors.lastname: Lautenschlager
authors.forename: Osvaldo P
authors.initials: OP
authors.lastname: Almeida
mesh_terms: D000368:Aged; D000375:Aging / Q000502:physiology*; D003072:Cognition Disorders / Q000453:epidemiology*; D015444:Exercise; D005260:Female; D006801:Humans; D008297:Male; D009043:Motor Activity; D012307:Risk Factors