title: Cardiorespiratory fitness, hippocampal volume, and frequency of forgetting in older adults.
abstract: OBJECTIVE
  The purpose of this study was to extend our earlier work to determine the extent to which cardiorespiratory fitness is associated with the frequency of memory problems via its effects on the hippocampus and spatial working memory. We hypothesized that age, sex, education, body composition, and physical activity were direct determinants of fitness, which, in turn, influenced frequency of forgetting indirectly through hippocampal volume and spatial working memory.
  
  
  METHODS
  We conducted assessments of demographic characteristics, Body Mass Index (BMI), physical activity, cardiorespiratory fitness, hippocampal volume, spatial working memory, and frequency of forgetting in 158 older adults (M age = 66.49). Path analyses within a covariance modeling framework were used to examine relationships among these constructs.
  
  
  RESULTS
  Sex, age, BMI, and education were all significant determinants of cardiorespiratory fitness. The hypothesized path models for testing the effects of fitness on frequency of forgetting through hippocampal volume and accuracy and speed of spatial working memory all fit the data well.
  
  
  CONCLUSIONS
  Our findings suggest that older adults with higher levels of fitness show greater preservation of hippocampal volume, which, in turn, is associated with more accurate and faster spatial memory and fewer episodes of forgetting. Given the proportion of older adults reporting memory problems, it is necessary to determine whether improvements in fitness brought about by physical activity interventions can result in subsequent attenuation of memory problems or potentially in improvements in memory.
authors.affiliation: Department of Kinesiology and Community Health, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
authors.forename: Amanda N
authors.initials: AN
authors.lastname: Szabo
authors.forename: Edward
authors.initials: E
authors.lastname: McAuley
authors.forename: Kirk I
authors.initials: KI
authors.lastname: Erickson
authors.forename: Michelle
authors.initials: M
authors.lastname: Voss
authors.forename: Ruchika S
authors.initials: RS
authors.lastname: Prakash
authors.forename: Emily L
authors.initials: EL
authors.lastname: Mailey
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Wójcicki
authors.forename: Siobhan M
authors.initials: SM
authors.lastname: White
authors.forename: Neha
authors.initials: N
authors.lastname: Gothe
authors.forename: Erin A
authors.initials: EA
authors.lastname: Olson
authors.forename: Arthur F
authors.initials: AF
authors.lastname: Kramer
mesh_terms: D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D015992:Body Mass Index; D015444:Exercise / Q000502:physiology; D005260:Female; D006624:Hippocampus / Q000033:anatomy & histology* / Q000502:physiology; D006801:Humans; D008297:Male; D018782:Maze Learning / Q000502:physiology*; D008570:Memory, Short-Term / Q000502:physiology*; D008875:Middle Aged; D015233:Models, Statistical; D009929:Organ Size; D010809:Physical Fitness / Q000502:physiology*; D012153:Retention, Psychology / Q000502:physiology*; D012737:Sex Factors; D013028:Space Perception / Q000502:physiology