title: The conceptualization and measurement of cognitive reserve using common proxy indicators: Testing some tenable reflective and formative models.
abstract: BACKGROUND
  The examination of cognitive reserve (CR) literature reveals a lack of consensus regarding conceptualization and pervasive problems with its measurement. This study aimed at examining the conceptual nature of CR through the analysis of reflective and formative models using eight proxies commonly employed in the CR literature. We hypothesized that all CR proxies would significantly contribute to a one-factor reflective model and that educational and occupational attainment would produce the strongest loadings on a single CR factor.
  
  
  METHODS
  The sample consisted of 149 participants (82 male/67 female), with 18.1 average years of education and ages of 45-99 years. Participants were assessed for eight proxies of CR (parent socioeconomic status, intellectual functioning, level of education, health literacy, occupational prestige, life leisure activities, physical activities, and spiritual and religious activities). Primary statistical analyses consisted of confirmatory factor analysis (CFA) to test reflective models and structural equation modeling (SEM) to evaluate multiple indicators multiple causes (MIMIC) models.
  
  
  RESULTS
  CFA did not produce compelling support for a unitary CR construct when using all eight of our CR proxy variables in a reflective model but fairly cogent evidence for a one-factor model with four variable proxies. A second three-factor reflective model based upon an exploratory principal components analysis of the eight proxies was tested using CFA. Though all eight indicators significantly loaded on their assigned factors, evidence in support of overall model fit was mixed. Based upon the results involving the three-factor reflective model, two alternative formative models were developed and evaluated. While some support was obtained for both, the model in which the formative influences were specified as latent variables appeared to best account for the contributions of all eight proxies to the CR construct.
  
  
  CONCLUSIONS
  While the findings provide partial support for our hypothesis regarding CR as a one-dimensional reflective construct, the results strongly suggest that the construct is more complex than what can be captured in a reflective model alone. There is a need for theory to better identify and differentiate formative from reflective indicators and to articulate the mechanisms by which CR develops and operates.
authors.affiliation: a Department of Rehabilitation Medicine , Emory University School of Medicine , Atlanta , GA , USA.|b Department of Psychology , University of Detroit Mercy , Detroit , MI , USA.
authors.forename: Jean
authors.initials: J
authors.lastname: Ikanga
authors.affiliation: b Department of Psychology , University of Detroit Mercy , Detroit , MI , USA.
authors.forename: Elizabeth M
authors.initials: EM
authors.lastname: Hill
authors.affiliation: b Department of Psychology , University of Detroit Mercy , Detroit , MI , USA.
authors.forename: Douglas A
authors.initials: DA
authors.lastname: MacDonald
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D058245:Cognitive Reserve / Q000502:physiology*; D003210:Concept Formation / Q000502:physiology*; D004522:Educational Status; D005260:Female; D006801:Humans; D007360:Intelligence / Q000502:physiology; D007899:Leisure Activities; D008297:Male; D008875:Middle Aged; D008960:Models, Psychological; D012923:Social Class
keywords: Cognitive reserve; Confirmatory factor analysis; Formative models; Multiple indicators multiple causes models; Reflective models