title: Schooling duration rather than chronological age predicts working memory between 6 and 7 years: Memory Maestros Study.
abstract: OBJECTIVE
  Low working memory (WM) is strongly linked with poor academic outcomes. WM capacity increases across childhood but how exposure to school is associated with WM development is not known. We aimed to determine extent to which chronological age and schooling duration are associated with WM at the population level.
  
  
  METHODS
  In 2012, children in Grade 1 (the second year of formal schooling in Victoria, Australia) from 44 schools in metropolitan Melbourne were recruited. Assessments occurred over the entire school year, with schools quasi-randomly allocated to one of the 4 school terms. WM (primary outcome) was measured using 2 subtests from the computerized Automated Working Memory Assessment: Backwards Digit Recall (verbal) and Mister X (visuospatial). Linear regression was used to examine relationships of WM with time in school and age.
  
  
  RESULTS
  Of the 1765 who provided consent, 1727 children (97.9%) had WM assessed throughout the 2012 school year. WM scores became steadily higher over the course of the year. Thus, scores were .77 and .53 SDs higher in Term 4 than Term 1 for verbal and visuospatial WM, respectively (p values for trend for both scores <.001); conclusions were unchanged when adjusted for age and potential confounders. Conversely, age associations attenuated fully once adjusted for school duration.
  
  
  CONCLUSIONS
  Our results demonstrate, for the first time, that the developmental increases in WM are strongly associated with time spent in the classroom, above and beyond chronological age.
authors.affiliation: *Population Health, Murdoch Childrens Research Institute, Melbourne, Australia; †Department of Paediatrics, The University of Melbourne, Melbourne, Australia; ‡Centre for Community Child Health, The Royal Children's Hospital, Melbourne, Australia; §MRC Cognition and Brain Sciences Unit, Cambridge, United Kingdom; ‖Deakin Health Economics, Deakin University, Melbourne, Australia; ¶School of Psychological Sciences, Monash University, Melbourne, Australia.
authors.forename: Gehan
authors.initials: G
authors.lastname: Roberts
authors.forename: Jon
authors.initials: J
authors.lastname: Quach
authors.forename: Fiona
authors.initials: F
authors.lastname: Mensah
authors.forename: Susan
authors.initials: S
authors.lastname: Gathercole
authors.forename: Lisa
authors.initials: L
authors.lastname: Gold
authors.forename: Peter
authors.initials: P
authors.lastname: Anderson
authors.forename: Megan
authors.initials: M
authors.lastname: Spencer-Smith
authors.forename: Melissa
authors.initials: M
authors.lastname: Wake
mesh_terms: D000367:Age Factors; D002648:Child; D002657:Child Development / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008570:Memory, Short-Term / Q000502:physiology*; D012574:Schools; D013997:Time Factors