title: Physical activity and cognitive functioning in the oldest old: Within- and between-person cognitive activity and psychosocial mediators.
abstract: OBJECTIVE
  The current study examines the role of social contact intensity, cognitive activity, and depressive symptoms as within- and between-person mediators for the relationships between physical activity and cognitive functioning.
  
  
  METHODS
  All three types of mediators were considered simultaneously using multilevel structural equations modeling with longitudinal data. The sample consisted of 470 adults ranging from 79.37 to 97.92 years of age (M = 83.4; SD = 3.2) at the first occasion.
  
  
  RESULTS
  Between-person differences in cognitive activity mediated the relationship between physical activity and cognitive functioning, such that individuals who participated in more physical activities, on average, engaged in more cognitive activities and, in turn, showed better cognitive functioning. Mediation of between-person associations between physical activity and memory through social contact intensity was also significant. At the within-person level, only cognitive activity mediated the relationship between physical activity and change in cognition; however, the indirect effect was small. Depressive symptomatology was not found to significantly mediate within- or between-person effects on cognitive change.
  
  
  CONCLUSIONS
  Our findings highlight the implications of physical activity participation for the prevention of cognitive decline and the importance of meditational processes at the between-person level. Physical activity can provide older adults with an avenue to make new friendships and engage in more cognitive activities which, in turn, attenuates cognitive decline.
authors.affiliation: Department of Psychology, University of Victoria, Victoria, BC, Canada V8W 3P5.
authors.forename: Annie
authors.initials: A
authors.lastname: Robitaille
authors.affiliation: MRC Unit for Life Long Health and Ageing, Medical Research Council, London, UK WC1B 5JU.
authors.forename: Graciela
authors.initials: G
authors.lastname: Muniz
authors.affiliation: Department of Food and Nutrition, and Sport Science, University of Gothenburg, Gothenburg, Sweden 405 30.
authors.forename: Magnus
authors.initials: M
authors.lastname: Lindwall
authors.affiliation: Department of Psychology, University of Victoria, Victoria, BC, Canada V8W 3P5.
authors.forename: Andrea M
authors.initials: AM
authors.lastname: Piccinin
authors.affiliation: Department of Psychology, University of Nebraska-Lincoln, Lincoln, NE, US 68588-0308.
authors.forename: Lesa
authors.initials: L
authors.lastname: Hoffman
authors.affiliation: Department of Psychology, University of Gothenburg, Gothenburg, Sweden 405 30.
authors.forename: Boo
authors.initials: B
authors.lastname: Johansson
authors.affiliation: Department of Psychology, University of Victoria, Victoria, BC, Canada V8W 3P5.
authors.forename: Scott M
authors.initials: SM
authors.lastname: Hofer
keywords: Ageing; Cognitive activity; Cognitive decline; Depression; Mediation; Multilevel Structural Equation Modeling; Physical activity; Social support